-// Copyright 2013 Google Inc. All Rights Reserved.
+// Copyright 2018 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
-// http://www.apache.org/licenses/LICENSE-2.0
+// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
-//
-// A btree implementation of the STL set and map interfaces. A btree is both
-// smaller and faster than STL set/map. The red-black tree implementation of
-// STL set/map has an overhead of 3 pointers (left, right and parent) plus the
-// node color information for each stored value. So a set<int32> consumes 20
-// bytes for each value stored. This btree implementation stores multiple
-// values on fixed size nodes (usually 256 bytes) and doesn't store child
-// pointers for leaf nodes. The result is that a btree_set<int32> may use much
-// less memory per stored value. For the random insertion benchmark in
-// btree_test.cc, a btree_set<int32> with node-size of 256 uses 4.9 bytes per
-// stored value.
+
+// A btree implementation of the STL set and map interfaces. A btree is smaller
+// and generally also faster than STL set/map (refer to the benchmarks below).
+// The red-black tree implementation of STL set/map has an overhead of 3
+// pointers (left, right and parent) plus the node color information for each
+// stored value. So a set<int32_t> consumes 40 bytes for each value stored in
+// 64-bit mode. This btree implementation stores multiple values on fixed
+// size nodes (usually 256 bytes) and doesn't store child pointers for leaf
+// nodes. The result is that a btree_set<int32_t> may use much less memory per
+// stored value. For the random insertion benchmark in btree_bench.cc, a
+// btree_set<int32_t> with node-size of 256 uses 5.1 bytes per stored value.
//
// The packing of multiple values on to each node of a btree has another effect
// besides better space utilization: better cache locality due to fewer cache
// rebalancing of btree nodes. And even without these operations, insertions
// and deletions on a btree will move values around within a node. In both
// cases, the result is that insertions and deletions can invalidate iterators
-// pointing to values other than the one being inserted/deleted. This is
-// notably different from STL set/map which takes care to not invalidate
-// iterators on insert/erase except, of course, for iterators pointing to the
-// value being erased. A partial workaround when erasing is available:
-// erase() returns an iterator pointing to the item just after the one that was
-// erased (or end() if none exists). See also safe_btree.
-
-// PERFORMANCE
-//
-// btree_bench --benchmarks=. 2>&1 | ./benchmarks.awk
-//
-// Run on pmattis-warp.nyc (4 X 2200 MHz CPUs); 2010/03/04-15:23:06
-// Benchmark STL(ns) B-Tree(ns) @ <size>
-// --------------------------------------------------------
-// BM_set_int32_insert 1516 608 +59.89% <256> [40.0, 5.2]
-// BM_set_int32_lookup 1160 414 +64.31% <256> [40.0, 5.2]
-// BM_set_int32_fulllookup 960 410 +57.29% <256> [40.0, 4.4]
-// BM_set_int32_delete 1741 528 +69.67% <256> [40.0, 5.2]
-// BM_set_int32_queueaddrem 3078 1046 +66.02% <256> [40.0, 5.5]
-// BM_set_int32_mixedaddrem 3600 1384 +61.56% <256> [40.0, 5.3]
-// BM_set_int32_fifo 227 113 +50.22% <256> [40.0, 4.4]
-// BM_set_int32_fwditer 158 26 +83.54% <256> [40.0, 5.2]
-// BM_map_int32_insert 1551 636 +58.99% <256> [48.0, 10.5]
-// BM_map_int32_lookup 1200 508 +57.67% <256> [48.0, 10.5]
-// BM_map_int32_fulllookup 989 487 +50.76% <256> [48.0, 8.8]
-// BM_map_int32_delete 1794 628 +64.99% <256> [48.0, 10.5]
-// BM_map_int32_queueaddrem 3189 1266 +60.30% <256> [48.0, 11.6]
-// BM_map_int32_mixedaddrem 3822 1623 +57.54% <256> [48.0, 10.9]
-// BM_map_int32_fifo 151 134 +11.26% <256> [48.0, 8.8]
-// BM_map_int32_fwditer 161 32 +80.12% <256> [48.0, 10.5]
-// BM_set_int64_insert 1546 636 +58.86% <256> [40.0, 10.5]
-// BM_set_int64_lookup 1200 512 +57.33% <256> [40.0, 10.5]
-// BM_set_int64_fulllookup 971 487 +49.85% <256> [40.0, 8.8]
-// BM_set_int64_delete 1745 616 +64.70% <256> [40.0, 10.5]
-// BM_set_int64_queueaddrem 3163 1195 +62.22% <256> [40.0, 11.6]
-// BM_set_int64_mixedaddrem 3760 1564 +58.40% <256> [40.0, 10.9]
-// BM_set_int64_fifo 146 103 +29.45% <256> [40.0, 8.8]
-// BM_set_int64_fwditer 162 31 +80.86% <256> [40.0, 10.5]
-// BM_map_int64_insert 1551 720 +53.58% <256> [48.0, 20.7]
-// BM_map_int64_lookup 1214 612 +49.59% <256> [48.0, 20.7]
-// BM_map_int64_fulllookup 994 592 +40.44% <256> [48.0, 17.2]
-// BM_map_int64_delete 1778 764 +57.03% <256> [48.0, 20.7]
-// BM_map_int64_queueaddrem 3189 1547 +51.49% <256> [48.0, 20.9]
-// BM_map_int64_mixedaddrem 3779 1887 +50.07% <256> [48.0, 21.6]
-// BM_map_int64_fifo 147 145 +1.36% <256> [48.0, 17.2]
-// BM_map_int64_fwditer 162 41 +74.69% <256> [48.0, 20.7]
-// BM_set_string_insert 1989 1966 +1.16% <256> [64.0, 44.5]
-// BM_set_string_lookup 1709 1600 +6.38% <256> [64.0, 44.5]
-// BM_set_string_fulllookup 1573 1529 +2.80% <256> [64.0, 35.4]
-// BM_set_string_delete 2520 1920 +23.81% <256> [64.0, 44.5]
-// BM_set_string_queueaddrem 4706 4309 +8.44% <256> [64.0, 48.3]
-// BM_set_string_mixedaddrem 5080 4654 +8.39% <256> [64.0, 46.7]
-// BM_set_string_fifo 318 512 -61.01% <256> [64.0, 35.4]
-// BM_set_string_fwditer 182 93 +48.90% <256> [64.0, 44.5]
-// BM_map_string_insert 2600 2227 +14.35% <256> [72.0, 55.8]
-// BM_map_string_lookup 2068 1730 +16.34% <256> [72.0, 55.8]
-// BM_map_string_fulllookup 1859 1618 +12.96% <256> [72.0, 44.0]
-// BM_map_string_delete 3168 2080 +34.34% <256> [72.0, 55.8]
-// BM_map_string_queueaddrem 5840 4701 +19.50% <256> [72.0, 59.4]
-// BM_map_string_mixedaddrem 6400 5200 +18.75% <256> [72.0, 57.8]
-// BM_map_string_fifo 398 596 -49.75% <256> [72.0, 44.0]
-// BM_map_string_fwditer 243 113 +53.50% <256> [72.0, 55.8]
-
-#ifndef UTIL_BTREE_BTREE_H__
-#define UTIL_BTREE_BTREE_H__
-
-#include <stddef.h>
-#include <string.h>
-#include <sys/types.h>
+// pointing to values other than the one being inserted/deleted. Therefore, this
+// container does not provide pointer stability. This is notably different from
+// STL set/map which takes care to not invalidate iterators on insert/erase
+// except, of course, for iterators pointing to the value being erased. A
+// partial workaround when erasing is available: erase() returns an iterator
+// pointing to the item just after the one that was erased (or end() if none
+// exists).
+
+#ifndef ABSL_CONTAINER_INTERNAL_BTREE_H_
+#define ABSL_CONTAINER_INTERNAL_BTREE_H_
+
#include <algorithm>
+#include <cassert>
+#include <cstddef>
+#include <cstdint>
+#include <cstring>
#include <functional>
-#include <iostream>
#include <iterator>
#include <limits>
-#include <type_traits>
#include <new>
-#include <ostream>
#include <string>
+#include <type_traits>
#include <utility>
-#include "include/ceph_assert.h"
+#include "absl/base/macros.h"
+#include "absl/container/internal/common.h"
+#include "absl/container/internal/compressed_tuple.h"
+#include "absl/container/internal/container_memory.h"
+#include "absl/container/internal/layout.h"
+#include "absl/memory/memory.h"
+#include "absl/meta/type_traits.h"
+#include "absl/strings/string_view.h"
+#include "absl/types/compare.h"
+#include "absl/utility/utility.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace container_internal {
+
+// A helper class that indicates if the Compare parameter is a key-compare-to
+// comparator.
+template <typename Compare, typename T>
+using btree_is_key_compare_to =
+ std::is_convertible<absl::result_of_t<Compare(const T &, const T &)>,
+ absl::weak_ordering>;
+
+struct StringBtreeDefaultLess {
+ using is_transparent = void;
+
+ StringBtreeDefaultLess() = default;
+
+ // Compatibility constructor.
+ StringBtreeDefaultLess(std::less<std::string>) {} // NOLINT
+ StringBtreeDefaultLess(std::less<string_view>) {} // NOLINT
+
+ absl::weak_ordering operator()(absl::string_view lhs,
+ absl::string_view rhs) const {
+ return compare_internal::compare_result_as_ordering(lhs.compare(rhs));
+ }
+};
-namespace btree {
+struct StringBtreeDefaultGreater {
+ using is_transparent = void;
-// Inside a btree method, if we just call swap(), it will choose the
-// btree::swap method, which we don't want. And we can't say ::swap
-// because then MSVC won't pickup any std::swap() implementations. We
-// can't just use std::swap() directly because then we don't get the
-// specialization for types outside the std namespace. So the solution
-// is to have a special swap helper function whose name doesn't
-// collide with other swap functions defined by the btree classes.
-template <typename T>
-inline void btree_swap_helper(T &a, T &b) {
- using std::swap;
- swap(a, b);
-}
+ StringBtreeDefaultGreater() = default;
-// Types small_ and big_ are promise that sizeof(small_) < sizeof(big_)
-typedef char small_;
+ StringBtreeDefaultGreater(std::greater<std::string>) {} // NOLINT
+ StringBtreeDefaultGreater(std::greater<string_view>) {} // NOLINT
-struct big_ {
- char dummy[2];
+ absl::weak_ordering operator()(absl::string_view lhs,
+ absl::string_view rhs) const {
+ return compare_internal::compare_result_as_ordering(rhs.compare(lhs));
+ }
};
-// A helper type used to indicate that a key-compare-to functor has been
-// provided. A user can specify a key-compare-to functor by doing:
-//
-// struct MyStringComparer
-// : public util::btree::btree_key_compare_to_tag {
-// int operator()(const string &a, const string &b) const {
-// return a.compare(b);
-// }
-// };
+// A helper class to convert a boolean comparison into a three-way "compare-to"
+// comparison that returns a negative value to indicate less-than, zero to
+// indicate equality and a positive value to indicate greater-than. This helper
+// class is specialized for less<std::string>, greater<std::string>,
+// less<string_view>, and greater<string_view>.
//
-// Note that the return type is an int and not a bool. There is a
-// COMPILE_ASSERT which enforces this return type.
-struct btree_key_compare_to_tag {
-};
-
-// A helper class that indicates if the Compare parameter is derived from
-// btree_key_compare_to_tag.
-template<typename Compare>
-inline constexpr bool btree_is_key_compare_to_v =
- std::is_convertible_v<Compare, btree_key_compare_to_tag>;
-
-// A helper class to convert a boolean comparison into a three-way
-// "compare-to" comparison that returns a negative value to indicate
-// less-than, zero to indicate equality and a positive value to
-// indicate greater-than. This helper class is specialized for
-// less<string> and greater<string>. The btree_key_compare_to_adapter
-// class is provided so that btree users automatically get the more
-// efficient compare-to code when using common google string types
-// with common comparison functors.
+// key_compare_to_adapter is provided so that btree users
+// automatically get the more efficient compare-to code when using common
+// google string types with common comparison functors.
+// These string-like specializations also turn on heterogeneous lookup by
+// default.
template <typename Compare>
-struct btree_key_compare_to_adapter : Compare {
- btree_key_compare_to_adapter() { }
- btree_key_compare_to_adapter(const Compare &c) : Compare(c) { }
- btree_key_compare_to_adapter(const btree_key_compare_to_adapter<Compare> &c)
- : Compare(c) {
- }
+struct key_compare_to_adapter {
+ using type = Compare;
};
template <>
-struct btree_key_compare_to_adapter<std::less<std::string> >
- : public btree_key_compare_to_tag {
- btree_key_compare_to_adapter() {}
- btree_key_compare_to_adapter(const std::less<std::string>&) {}
- btree_key_compare_to_adapter(
- const btree_key_compare_to_adapter<std::less<std::string> >&) {}
- int operator()(const std::string &a, const std::string &b) const {
- return a.compare(b);
- }
+struct key_compare_to_adapter<std::less<std::string>> {
+ using type = StringBtreeDefaultLess;
};
template <>
-struct btree_key_compare_to_adapter<std::greater<std::string> >
- : public btree_key_compare_to_tag {
- btree_key_compare_to_adapter() {}
- btree_key_compare_to_adapter(const std::greater<std::string>&) {}
- btree_key_compare_to_adapter(
- const btree_key_compare_to_adapter<std::greater<std::string> >&) {}
- int operator()(const std::string &a, const std::string &b) const {
- return b.compare(a);
- }
+struct key_compare_to_adapter<std::greater<std::string>> {
+ using type = StringBtreeDefaultGreater;
};
-// A helper class that allows a compare-to functor to behave like a plain
-// compare functor. This specialization is used when we do not have a
-// compare-to functor.
-template <typename Key, typename Compare, bool HaveCompareTo>
-struct btree_key_comparer {
- btree_key_comparer() {}
- btree_key_comparer(Compare c) : comp(c) {}
- static bool bool_compare(const Compare &comp, const Key &x, const Key &y) {
- return comp(x, y);
- }
- bool operator()(const Key &x, const Key &y) const {
- return bool_compare(comp, x, y);
- }
- Compare comp;
+template <>
+struct key_compare_to_adapter<std::less<absl::string_view>> {
+ using type = StringBtreeDefaultLess;
};
-// A specialization of btree_key_comparer when a compare-to functor is
-// present. We need a plain (boolean) comparison in some parts of the btree
-// code, such as insert-with-hint.
-template <typename Key, typename Compare>
-struct btree_key_comparer<Key, Compare, true> {
- btree_key_comparer() {}
- btree_key_comparer(Compare c) : comp(c) {}
- static bool bool_compare(const Compare &comp, const Key &x, const Key &y) {
- return comp(x, y) < 0;
- }
- bool operator()(const Key &x, const Key &y) const {
- return bool_compare(comp, x, y);
- }
- Compare comp;
+template <>
+struct key_compare_to_adapter<std::greater<absl::string_view>> {
+ using type = StringBtreeDefaultGreater;
};
-// A helper function to compare to keys using the specified compare
-// functor. This dispatches to the appropriate btree_key_comparer comparison,
-// depending on whether we have a compare-to functor or not (which depends on
-// whether Compare is derived from btree_key_compare_to_tag).
-template <typename Key, typename Compare>
-static bool btree_compare_keys(
- const Compare &comp, const Key &x, const Key &y) {
- typedef btree_key_comparer<Key, Compare,
- btree_is_key_compare_to_v<Compare>> key_comparer;
- return key_comparer::bool_compare(comp, x, y);
-}
-
-template <typename Key, typename Compare,
- typename Alloc, int TargetNodeSize, int ValueSize>
-struct btree_common_params {
- // If Compare is derived from btree_key_compare_to_tag then use it as the
- // key_compare type. Otherwise, use btree_key_compare_to_adapter<> which will
- // fall-back to Compare if we don't have an appropriate specialization.
- using key_compare = std::conditional_t<
- btree_is_key_compare_to_v<Compare>,
- Compare, btree_key_compare_to_adapter<Compare> >;
+template <typename Key, typename Compare, typename Alloc, int TargetNodeSize,
+ bool Multi, typename SlotPolicy>
+struct common_params {
+ // If Compare is a common comparator for a std::string-like type, then we adapt it
+ // to use heterogeneous lookup and to be a key-compare-to comparator.
+ using key_compare = typename key_compare_to_adapter<Compare>::type;
// A type which indicates if we have a key-compare-to functor or a plain old
// key-compare functor.
- static constexpr bool is_key_compare_to = btree_is_key_compare_to_v<key_compare>;
+ using is_key_compare_to = btree_is_key_compare_to<key_compare, Key>;
+
+ using allocator_type = Alloc;
+ using key_type = Key;
+ using size_type = std::make_signed<size_t>::type;
+ using difference_type = ptrdiff_t;
- typedef Alloc allocator_type;
- typedef Key key_type;
- typedef ssize_t size_type;
- typedef ptrdiff_t difference_type;
+ // True if this is a multiset or multimap.
+ using is_multi_container = std::integral_constant<bool, Multi>;
+
+ using slot_policy = SlotPolicy;
+ using slot_type = typename slot_policy::slot_type;
+ using value_type = typename slot_policy::value_type;
+ using init_type = typename slot_policy::mutable_value_type;
+ using pointer = value_type *;
+ using const_pointer = const value_type *;
+ using reference = value_type &;
+ using const_reference = const value_type &;
enum {
kTargetNodeSize = TargetNodeSize,
- // Available space for values. This is largest for leaf nodes,
- // which has overhead no fewer than two pointers.
- kNodeValueSpace = TargetNodeSize - 2 * sizeof(void*),
+ // Upper bound for the available space for values. This is largest for leaf
+ // nodes, which have overhead of at least a pointer + 4 bytes (for storing
+ // 3 field_types and an enum).
+ kNodeValueSpace =
+ TargetNodeSize - /*minimum overhead=*/(sizeof(void *) + 4),
};
// This is an integral type large enough to hold as many
// ValueSize-values as will fit a node of TargetNodeSize bytes.
- using node_count_type = std::conditional_t<
- (kNodeValueSpace / ValueSize) >= 256,
- uint16_t,
- uint8_t>;
+ using node_count_type =
+ absl::conditional_t<(kNodeValueSpace / sizeof(value_type) >
+ (std::numeric_limits<uint8_t>::max)()),
+ uint16_t, uint8_t>; // NOLINT
+
+ // The following methods are necessary for passing this struct as PolicyTraits
+ // for node_handle and/or are used within btree.
+ static value_type &element(slot_type *slot) {
+ return slot_policy::element(slot);
+ }
+ static const value_type &element(const slot_type *slot) {
+ return slot_policy::element(slot);
+ }
+ template <class... Args>
+ static void construct(Alloc *alloc, slot_type *slot, Args &&... args) {
+ slot_policy::construct(alloc, slot, std::forward<Args>(args)...);
+ }
+ static void construct(Alloc *alloc, slot_type *slot, slot_type *other) {
+ slot_policy::construct(alloc, slot, other);
+ }
+ static void destroy(Alloc *alloc, slot_type *slot) {
+ slot_policy::destroy(alloc, slot);
+ }
+ static void transfer(Alloc *alloc, slot_type *new_slot, slot_type *old_slot) {
+ construct(alloc, new_slot, old_slot);
+ destroy(alloc, old_slot);
+ }
+ static void swap(Alloc *alloc, slot_type *a, slot_type *b) {
+ slot_policy::swap(alloc, a, b);
+ }
+ static void move(Alloc *alloc, slot_type *src, slot_type *dest) {
+ slot_policy::move(alloc, src, dest);
+ }
+ static void move(Alloc *alloc, slot_type *first, slot_type *last,
+ slot_type *result) {
+ slot_policy::move(alloc, first, last, result);
+ }
};
// A parameters structure for holding the type parameters for a btree_map.
-template <typename Key, typename Data, typename Compare,
- typename Alloc, int TargetNodeSize>
-struct btree_map_params
- : public btree_common_params<Key, Compare, Alloc, TargetNodeSize,
- sizeof(Key) + sizeof(Data)> {
- typedef Data data_type;
- typedef Data mapped_type;
- typedef std::pair<const Key, data_type> value_type;
- typedef std::pair<Key, data_type> mutable_value_type;
- typedef value_type* pointer;
- typedef const value_type* const_pointer;
- typedef value_type& reference;
- typedef const value_type& const_reference;
-
- enum {
- kValueSize = sizeof(Key) + sizeof(data_type),
+// Compare and Alloc should be nothrow copy-constructible.
+template <typename Key, typename Data, typename Compare, typename Alloc,
+ int TargetNodeSize, bool Multi>
+struct map_params : common_params<Key, Compare, Alloc, TargetNodeSize, Multi,
+ map_slot_policy<Key, Data>> {
+ using super_type = typename map_params::common_params;
+ using mapped_type = Data;
+ // This type allows us to move keys when it is safe to do so. It is safe
+ // for maps in which value_type and mutable_value_type are layout compatible.
+ using slot_policy = typename super_type::slot_policy;
+ using slot_type = typename super_type::slot_type;
+ using value_type = typename super_type::value_type;
+ using init_type = typename super_type::init_type;
+
+ using key_compare = typename super_type::key_compare;
+ // Inherit from key_compare for empty base class optimization.
+ struct value_compare : private key_compare {
+ value_compare() = default;
+ explicit value_compare(const key_compare &cmp) : key_compare(cmp) {}
+
+ template <typename T, typename U>
+ auto operator()(const T &left, const U &right) const
+ -> decltype(std::declval<key_compare>()(left.first, right.first)) {
+ return key_compare::operator()(left.first, right.first);
+ }
};
+ using is_map_container = std::true_type;
- static const Key& key(const value_type &x) { return x.first; }
- static const Key& key(const mutable_value_type &x) { return x.first; }
- static void swap(mutable_value_type *a, mutable_value_type *b) {
- btree_swap_helper(a->first, b->first);
- btree_swap_helper(a->second, b->second);
- }
+ static const Key &key(const value_type &x) { return x.first; }
+ static const Key &key(const init_type &x) { return x.first; }
+ static const Key &key(const slot_type *x) { return slot_policy::key(x); }
+ static mapped_type &value(value_type *value) { return value->second; }
};
-// A parameters structure for holding the type parameters for a btree_set.
-template <typename Key, typename Compare, typename Alloc, int TargetNodeSize>
-struct btree_set_params
- : public btree_common_params<Key, Compare, Alloc, TargetNodeSize,
- sizeof(Key)> {
- typedef std::false_type data_type;
- typedef std::false_type mapped_type;
- typedef Key value_type;
- typedef value_type mutable_value_type;
- typedef value_type* pointer;
- typedef const value_type* const_pointer;
- typedef value_type& reference;
- typedef const value_type& const_reference;
+// This type implements the necessary functions from the
+// absl::container_internal::slot_type interface.
+template <typename Key>
+struct set_slot_policy {
+ using slot_type = Key;
+ using value_type = Key;
+ using mutable_value_type = Key;
- enum {
- kValueSize = sizeof(Key),
- };
+ static value_type &element(slot_type *slot) { return *slot; }
+ static const value_type &element(const slot_type *slot) { return *slot; }
- static const Key& key(const value_type &x) { return x; }
- static void swap(mutable_value_type *a, mutable_value_type *b) {
- btree_swap_helper<mutable_value_type>(*a, *b);
+ template <typename Alloc, class... Args>
+ static void construct(Alloc *alloc, slot_type *slot, Args &&... args) {
+ absl::allocator_traits<Alloc>::construct(*alloc, slot,
+ std::forward<Args>(args)...);
}
-};
-// An adapter class that converts a lower-bound compare into an upper-bound
-// compare.
-template <typename Key, typename Compare>
-struct btree_upper_bound_adapter : public Compare {
- btree_upper_bound_adapter(Compare c) : Compare(c) {}
- bool operator()(const Key &a, const Key &b) const {
- return !static_cast<const Compare&>(*this)(b, a);
+ template <typename Alloc>
+ static void construct(Alloc *alloc, slot_type *slot, slot_type *other) {
+ absl::allocator_traits<Alloc>::construct(*alloc, slot, std::move(*other));
}
-};
-template <typename Key, typename CompareTo>
-struct btree_upper_bound_compare_to_adapter : public CompareTo {
- btree_upper_bound_compare_to_adapter(CompareTo c) : CompareTo(c) {}
- int operator()(const Key &a, const Key &b) const {
- return static_cast<const CompareTo&>(*this)(b, a);
+ template <typename Alloc>
+ static void destroy(Alloc *alloc, slot_type *slot) {
+ absl::allocator_traits<Alloc>::destroy(*alloc, slot);
}
-};
-// Dispatch helper class for using linear search with plain compare.
-template <typename K, typename N, typename Compare>
-struct btree_linear_search_plain_compare {
- static int lower_bound(const K &k, const N &n, Compare comp) {
- return n.linear_search_plain_compare(k, 0, n.count(), comp);
- }
- static int upper_bound(const K &k, const N &n, Compare comp) {
- typedef btree_upper_bound_adapter<K, Compare> upper_compare;
- return n.linear_search_plain_compare(k, 0, n.count(), upper_compare(comp));
+ template <typename Alloc>
+ static void swap(Alloc * /*alloc*/, slot_type *a, slot_type *b) {
+ using std::swap;
+ swap(*a, *b);
}
-};
-// Dispatch helper class for using linear search with compare-to
-template <typename K, typename N, typename CompareTo>
-struct btree_linear_search_compare_to {
- static int lower_bound(const K &k, const N &n, CompareTo comp) {
- return n.linear_search_compare_to(k, 0, n.count(), comp);
+ template <typename Alloc>
+ static void move(Alloc * /*alloc*/, slot_type *src, slot_type *dest) {
+ *dest = std::move(*src);
}
- static int upper_bound(const K &k, const N &n, CompareTo comp) {
- typedef btree_upper_bound_adapter<K,
- btree_key_comparer<K, CompareTo, true> > upper_compare;
- return n.linear_search_plain_compare(k, 0, n.count(), upper_compare(comp));
+
+ template <typename Alloc>
+ static void move(Alloc *alloc, slot_type *first, slot_type *last,
+ slot_type *result) {
+ for (slot_type *src = first, *dest = result; src != last; ++src, ++dest)
+ move(alloc, src, dest);
}
};
-// Dispatch helper class for using binary search with plain compare.
-template <typename K, typename N, typename Compare>
-struct btree_binary_search_plain_compare {
- static int lower_bound(const K &k, const N &n, Compare comp) {
- return n.binary_search_plain_compare(k, 0, n.count(), comp);
- }
- static int upper_bound(const K &k, const N &n, Compare comp) {
- typedef btree_upper_bound_adapter<K, Compare> upper_compare;
- return n.binary_search_plain_compare(k, 0, n.count(), upper_compare(comp));
- }
+// A parameters structure for holding the type parameters for a btree_set.
+// Compare and Alloc should be nothrow copy-constructible.
+template <typename Key, typename Compare, typename Alloc, int TargetNodeSize,
+ bool Multi>
+struct set_params : common_params<Key, Compare, Alloc, TargetNodeSize, Multi,
+ set_slot_policy<Key>> {
+ using value_type = Key;
+ using slot_type = typename set_params::common_params::slot_type;
+ using value_compare = typename set_params::common_params::key_compare;
+ using is_map_container = std::false_type;
+
+ static const Key &key(const value_type &x) { return x; }
+ static const Key &key(const slot_type *x) { return *x; }
};
-// Dispatch helper class for using binary search with compare-to.
-template <typename K, typename N, typename CompareTo>
-struct btree_binary_search_compare_to {
- static int lower_bound(const K &k, const N &n, CompareTo comp) {
- return n.binary_search_compare_to(k, 0, n.count(), CompareTo());
- }
- static int upper_bound(const K &k, const N &n, CompareTo comp) {
- typedef btree_upper_bound_adapter<K,
- btree_key_comparer<K, CompareTo, true> > upper_compare;
- return n.linear_search_plain_compare(k, 0, n.count(), upper_compare(comp));
+// An adapter class that converts a lower-bound compare into an upper-bound
+// compare. Note: there is no need to make a version of this adapter specialized
+// for key-compare-to functors because the upper-bound (the first value greater
+// than the input) is never an exact match.
+template <typename Compare>
+struct upper_bound_adapter {
+ explicit upper_bound_adapter(const Compare &c) : comp(c) {}
+ template <typename K, typename LK>
+ bool operator()(const K &a, const LK &b) const {
+ // Returns true when a is not greater than b.
+ return !compare_internal::compare_result_as_less_than(comp(b, a));
}
+
+ private:
+ Compare comp;
+};
+
+enum class MatchKind : uint8_t { kEq, kNe };
+
+template <typename V, bool IsCompareTo>
+struct SearchResult {
+ V value;
+ MatchKind match;
+
+ static constexpr bool HasMatch() { return true; }
+ bool IsEq() const { return match == MatchKind::kEq; }
+};
+
+// When we don't use CompareTo, `match` is not present.
+// This ensures that callers can't use it accidentally when it provides no
+// useful information.
+template <typename V>
+struct SearchResult<V, false> {
+ V value;
+
+ static constexpr bool HasMatch() { return false; }
+ static constexpr bool IsEq() { return false; }
};
// A node in the btree holding. The same node type is used for both internal
// that the children array is only valid in internal nodes.
template <typename Params>
class btree_node {
+ using is_key_compare_to = typename Params::is_key_compare_to;
+ using is_multi_container = typename Params::is_multi_container;
+ using field_type = typename Params::node_count_type;
+ using allocator_type = typename Params::allocator_type;
+ using slot_type = typename Params::slot_type;
+
public:
- typedef Params params_type;
- typedef btree_node<Params> self_type;
- typedef typename Params::key_type key_type;
- typedef typename Params::data_type data_type;
- typedef typename Params::value_type value_type;
- typedef typename Params::mutable_value_type mutable_value_type;
- typedef typename Params::pointer pointer;
- typedef typename Params::const_pointer const_pointer;
- typedef typename Params::reference reference;
- typedef typename Params::const_reference const_reference;
- typedef typename Params::key_compare key_compare;
- typedef typename Params::size_type size_type;
- typedef typename Params::difference_type difference_type;
- // Typedefs for the various types of node searches.
- typedef btree_linear_search_plain_compare<
- key_type, self_type, key_compare> linear_search_plain_compare_type;
- typedef btree_linear_search_compare_to<
- key_type, self_type, key_compare> linear_search_compare_to_type;
- typedef btree_binary_search_plain_compare<
- key_type, self_type, key_compare> binary_search_plain_compare_type;
- typedef btree_binary_search_compare_to<
- key_type, self_type, key_compare> binary_search_compare_to_type;
- // If we have a valid key-compare-to type, use linear_search_compare_to,
- // otherwise use linear_search_plain_compare.
- using linear_search_type = std::conditional_t<
- Params::is_key_compare_to,
- linear_search_compare_to_type,
- linear_search_plain_compare_type>;
- // If we have a valid key-compare-to type, use binary_search_compare_to,
- // otherwise use binary_search_plain_compare.
- using binary_search_type = std::conditional_t<
- Params::is_key_compare_to,
- binary_search_compare_to_type,
- binary_search_plain_compare_type>;
- // If the key is an integral or floating point type, use linear search which
- // is faster than binary search for such types. Might be wise to also
- // configure linear search based on node-size.
- using search_type = std::conditional_t<
- std::is_integral<key_type>::value ||
- std::is_floating_point<key_type>::value,
- linear_search_type, binary_search_type>;
-
- struct base_fields {
- typedef typename Params::node_count_type field_type;
-
- // A boolean indicating whether the node is a leaf or not.
- bool leaf;
- // The position of the node in the node's parent.
- field_type position;
- // The maximum number of values the node can hold.
- field_type max_count;
- // The count of the number of values in the node.
- field_type count;
- // A pointer to the node's parent.
- btree_node *parent;
- };
+ using params_type = Params;
+ using key_type = typename Params::key_type;
+ using value_type = typename Params::value_type;
+ using pointer = typename Params::pointer;
+ using const_pointer = typename Params::const_pointer;
+ using reference = typename Params::reference;
+ using const_reference = typename Params::const_reference;
+ using key_compare = typename Params::key_compare;
+ using size_type = typename Params::size_type;
+ using difference_type = typename Params::difference_type;
+
+ // Btree decides whether to use linear node search as follows:
+ // - If the key is arithmetic and the comparator is std::less or
+ // std::greater, choose linear.
+ // - Otherwise, choose binary.
+ // TODO(ezb): Might make sense to add condition(s) based on node-size.
+ using use_linear_search = std::integral_constant<
+ bool,
+ std::is_arithmetic<key_type>::value &&
+ (std::is_same<std::less<key_type>, key_compare>::value ||
+ std::is_same<std::greater<key_type>, key_compare>::value)>;
+
+ // This class is organized by gtl::Layout as if it had the following
+ // structure:
+ // // A pointer to the node's parent.
+ // btree_node *parent;
+ //
+ // // The position of the node in the node's parent.
+ // field_type position;
+ // // The index of the first populated value in `values`.
+ // // TODO(ezb): right now, `start` is always 0. Update insertion/merge
+ // // logic to allow for floating storage within nodes.
+ // field_type start;
+ // // The count of the number of populated values in the node.
+ // field_type count;
+ // // The maximum number of values the node can hold. This is an integer in
+ // // [1, kNodeValues] for root leaf nodes, kNodeValues for non-root leaf
+ // // nodes, and kInternalNodeMaxCount (as a sentinel value) for internal
+ // // nodes (even though there are still kNodeValues values in the node).
+ // // TODO(ezb): make max_count use only 4 bits and record log2(capacity)
+ // // to free extra bits for is_root, etc.
+ // field_type max_count;
+ //
+ // // The array of values. The capacity is `max_count` for leaf nodes and
+ // // kNodeValues for internal nodes. Only the values in
+ // // [start, start + count) have been initialized and are valid.
+ // slot_type values[max_count];
+ //
+ // // The array of child pointers. The keys in children[i] are all less
+ // // than key(i). The keys in children[i + 1] are all greater than key(i).
+ // // There are 0 children for leaf nodes and kNodeValues + 1 children for
+ // // internal nodes.
+ // btree_node *children[kNodeValues + 1];
+ //
+ // This class is only constructed by EmptyNodeType. Normally, pointers to the
+ // layout above are allocated, cast to btree_node*, and de-allocated within
+ // the btree implementation.
+ ~btree_node() = default;
+ btree_node(btree_node const &) = delete;
+ btree_node &operator=(btree_node const &) = delete;
+
+ // Public for EmptyNodeType.
+ constexpr static size_type Alignment() {
+ static_assert(LeafLayout(1).Alignment() == InternalLayout().Alignment(),
+ "Alignment of all nodes must be equal.");
+ return InternalLayout().Alignment();
+ }
+
+ protected:
+ btree_node() = default;
+
+ private:
+ using layout_type = absl::container_internal::Layout<btree_node *, field_type,
+ slot_type, btree_node *>;
+ constexpr static size_type SizeWithNValues(size_type n) {
+ return layout_type(/*parent*/ 1,
+ /*position, start, count, max_count*/ 4,
+ /*values*/ n,
+ /*children*/ 0)
+ .AllocSize();
+ }
+ // A lower bound for the overhead of fields other than values in a leaf node.
+ constexpr static size_type MinimumOverhead() {
+ return SizeWithNValues(1) - sizeof(value_type);
+ }
+
+ // Compute how many values we can fit onto a leaf node taking into account
+ // padding.
+ constexpr static size_type NodeTargetValues(const int begin, const int end) {
+ return begin == end ? begin
+ : SizeWithNValues((begin + end) / 2 + 1) >
+ params_type::kTargetNodeSize
+ ? NodeTargetValues(begin, (begin + end) / 2)
+ : NodeTargetValues((begin + end) / 2 + 1, end);
+ }
enum {
- kValueSize = params_type::kValueSize,
kTargetNodeSize = params_type::kTargetNodeSize,
+ kNodeTargetValues = NodeTargetValues(0, params_type::kTargetNodeSize),
- // Compute how many values we can fit onto a leaf node.
- kNodeTargetValues = (kTargetNodeSize - sizeof(base_fields)) / kValueSize,
// We need a minimum of 3 values per internal node in order to perform
// splitting (1 value for the two nodes involved in the split and 1 value
// propagated to the parent as the delimiter for the split).
kNodeValues = kNodeTargetValues >= 3 ? kNodeTargetValues : 3,
- kExactMatch = 1 << 30,
- kMatchMask = kExactMatch - 1,
- };
-
- struct leaf_fields : public base_fields {
- // The array of values. Only the first count of these values have been
- // constructed and are valid.
- mutable_value_type values[kNodeValues];
+ // The node is internal (i.e. is not a leaf node) if and only if `max_count`
+ // has this value.
+ kInternalNodeMaxCount = 0,
};
- struct internal_fields : public leaf_fields {
- // The array of child pointers. The keys in children_[i] are all less than
- // key(i). The keys in children_[i + 1] are all greater than key(i). There
- // are always count + 1 children.
- btree_node *children[kNodeValues + 1];
- };
-
- struct root_fields : public internal_fields {
- btree_node *rightmost;
- size_type size;
- };
+ // Leaves can have less than kNodeValues values.
+ constexpr static layout_type LeafLayout(const int max_values = kNodeValues) {
+ return layout_type(/*parent*/ 1,
+ /*position, start, count, max_count*/ 4,
+ /*values*/ max_values,
+ /*children*/ 0);
+ }
+ constexpr static layout_type InternalLayout() {
+ return layout_type(/*parent*/ 1,
+ /*position, start, count, max_count*/ 4,
+ /*values*/ kNodeValues,
+ /*children*/ kNodeValues + 1);
+ }
+ constexpr static size_type LeafSize(const int max_values = kNodeValues) {
+ return LeafLayout(max_values).AllocSize();
+ }
+ constexpr static size_type InternalSize() {
+ return InternalLayout().AllocSize();
+ }
+
+ // N is the index of the type in the Layout definition.
+ // ElementType<N> is the Nth type in the Layout definition.
+ template <size_type N>
+ inline typename layout_type::template ElementType<N> *GetField() {
+ // We assert that we don't read from values that aren't there.
+ assert(N < 3 || !leaf());
+ return InternalLayout().template Pointer<N>(reinterpret_cast<char *>(this));
+ }
+ template <size_type N>
+ inline const typename layout_type::template ElementType<N> *GetField() const {
+ assert(N < 3 || !leaf());
+ return InternalLayout().template Pointer<N>(
+ reinterpret_cast<const char *>(this));
+ }
+ void set_parent(btree_node *p) { *GetField<0>() = p; }
+ field_type &mutable_count() { return GetField<1>()[2]; }
+ slot_type *slot(int i) { return &GetField<2>()[i]; }
+ const slot_type *slot(int i) const { return &GetField<2>()[i]; }
+ void set_position(field_type v) { GetField<1>()[0] = v; }
+ void set_start(field_type v) { GetField<1>()[1] = v; }
+ void set_count(field_type v) { GetField<1>()[2] = v; }
+ // This method is only called by the node init methods.
+ void set_max_count(field_type v) { GetField<1>()[3] = v; }
public:
- // Getter/setter for whether this is a leaf node or not. This value doesn't
- // change after the node is created.
- bool leaf() const { return fields_.leaf; }
+ // Whether this is a leaf node or not. This value doesn't change after the
+ // node is created.
+ bool leaf() const { return GetField<1>()[3] != kInternalNodeMaxCount; }
// Getter for the position of this node in its parent.
- int position() const { return fields_.position; }
- void set_position(int v) { fields_.position = v; }
+ field_type position() const { return GetField<1>()[0]; }
- // Getter/setter for the number of values stored in this node.
- int count() const { return fields_.count; }
- void set_count(int v) { fields_.count = v; }
- int max_count() const { return fields_.max_count; }
+ // Getter for the offset of the first value in the `values` array.
+ field_type start() const { return GetField<1>()[1]; }
+
+ // Getters for the number of values stored in this node.
+ field_type count() const { return GetField<1>()[2]; }
+ field_type max_count() const {
+ // Internal nodes have max_count==kInternalNodeMaxCount.
+ // Leaf nodes have max_count in [1, kNodeValues].
+ const field_type max_count = GetField<1>()[3];
+ return max_count == field_type{kInternalNodeMaxCount}
+ ? field_type{kNodeValues}
+ : max_count;
+ }
// Getter for the parent of this node.
- btree_node* parent() const { return fields_.parent; }
+ btree_node *parent() const { return *GetField<0>(); }
// Getter for whether the node is the root of the tree. The parent of the
// root of the tree is the leftmost node in the tree which is guaranteed to
// be a leaf.
bool is_root() const { return parent()->leaf(); }
void make_root() {
- ceph_assert(parent()->is_root());
- fields_.parent = fields_.parent->parent();
+ assert(parent()->is_root());
+ set_parent(parent()->parent());
}
- // Getter for the rightmost root node field. Only valid on the root node.
- btree_node* rightmost() const { return fields_.rightmost; }
- btree_node** mutable_rightmost() { return &fields_.rightmost; }
-
- // Getter for the size root node field. Only valid on the root node.
- size_type size() const { return fields_.size; }
- size_type* mutable_size() { return &fields_.size; }
-
// Getters for the key/value at position i in the node.
- const key_type& key(int i) const {
- return params_type::key(fields_.values[i]);
- }
- reference value(int i) {
- return reinterpret_cast<reference>(fields_.values[i]);
- }
- const_reference value(int i) const {
- return reinterpret_cast<const_reference>(fields_.values[i]);
- }
- mutable_value_type* mutable_value(int i) {
- return &fields_.values[i];
- }
-
- // Swap value i in this node with value j in node x.
- void value_swap(int i, btree_node *x, int j) {
- params_type::swap(mutable_value(i), x->mutable_value(j));
- }
+ const key_type &key(int i) const { return params_type::key(slot(i)); }
+ reference value(int i) { return params_type::element(slot(i)); }
+ const_reference value(int i) const { return params_type::element(slot(i)); }
// Getters/setter for the child at position i in the node.
- btree_node* child(int i) const { return fields_.children[i]; }
- btree_node** mutable_child(int i) { return &fields_.children[i]; }
+ btree_node *child(int i) const { return GetField<3>()[i]; }
+ btree_node *&mutable_child(int i) { return GetField<3>()[i]; }
+ void clear_child(int i) {
+ absl::container_internal::SanitizerPoisonObject(&mutable_child(i));
+ }
void set_child(int i, btree_node *c) {
- *mutable_child(i) = c;
- c->fields_.parent = this;
- c->fields_.position = i;
+ absl::container_internal::SanitizerUnpoisonObject(&mutable_child(i));
+ mutable_child(i) = c;
+ c->set_position(i);
+ }
+ void init_child(int i, btree_node *c) {
+ set_child(i, c);
+ c->set_parent(this);
}
// Returns the position of the first value whose key is not less than k.
- template <typename Compare>
- int lower_bound(const key_type &k, const Compare &comp) const {
- return search_type::lower_bound(k, *this, comp);
+ template <typename K>
+ SearchResult<int, is_key_compare_to::value> lower_bound(
+ const K &k, const key_compare &comp) const {
+ return use_linear_search::value ? linear_search(k, comp)
+ : binary_search(k, comp);
}
// Returns the position of the first value whose key is greater than k.
- template <typename Compare>
- int upper_bound(const key_type &k, const Compare &comp) const {
- return search_type::upper_bound(k, *this, comp);
+ template <typename K>
+ int upper_bound(const K &k, const key_compare &comp) const {
+ auto upper_compare = upper_bound_adapter<key_compare>(comp);
+ return use_linear_search::value ? linear_search(k, upper_compare).value
+ : binary_search(k, upper_compare).value;
+ }
+
+ template <typename K, typename Compare>
+ SearchResult<int, btree_is_key_compare_to<Compare, key_type>::value>
+ linear_search(const K &k, const Compare &comp) const {
+ return linear_search_impl(k, 0, count(), comp,
+ btree_is_key_compare_to<Compare, key_type>());
+ }
+
+ template <typename K, typename Compare>
+ SearchResult<int, btree_is_key_compare_to<Compare, key_type>::value>
+ binary_search(const K &k, const Compare &comp) const {
+ return binary_search_impl(k, 0, count(), comp,
+ btree_is_key_compare_to<Compare, key_type>());
}
// Returns the position of the first value whose key is not less than k using
// linear search performed using plain compare.
- template <typename Compare>
- int linear_search_plain_compare(
- const key_type &k, int s, int e, const Compare &comp) const {
+ template <typename K, typename Compare>
+ SearchResult<int, false> linear_search_impl(
+ const K &k, int s, const int e, const Compare &comp,
+ std::false_type /* IsCompareTo */) const {
while (s < e) {
- if (!btree_compare_keys(comp, key(s), k)) {
+ if (!comp(key(s), k)) {
break;
}
++s;
}
- return s;
+ return {s};
}
// Returns the position of the first value whose key is not less than k using
// linear search performed using compare-to.
- template <typename Compare>
- int linear_search_compare_to(
- const key_type &k, int s, int e, const Compare &comp) const {
+ template <typename K, typename Compare>
+ SearchResult<int, true> linear_search_impl(
+ const K &k, int s, const int e, const Compare &comp,
+ std::true_type /* IsCompareTo */) const {
while (s < e) {
- int c = comp(key(s), k);
+ const absl::weak_ordering c = comp(key(s), k);
if (c == 0) {
- return s | kExactMatch;
+ return {s, MatchKind::kEq};
} else if (c > 0) {
break;
}
++s;
}
- return s;
+ return {s, MatchKind::kNe};
}
// Returns the position of the first value whose key is not less than k using
// binary search performed using plain compare.
- template <typename Compare>
- int binary_search_plain_compare(
- const key_type &k, int s, int e, const Compare &comp) const {
+ template <typename K, typename Compare>
+ SearchResult<int, false> binary_search_impl(
+ const K &k, int s, int e, const Compare &comp,
+ std::false_type /* IsCompareTo */) const {
while (s != e) {
- int mid = (s + e) / 2;
- if (btree_compare_keys(comp, key(mid), k)) {
+ const int mid = (s + e) >> 1;
+ if (comp(key(mid), k)) {
s = mid + 1;
} else {
e = mid;
}
}
- return s;
+ return {s};
}
// Returns the position of the first value whose key is not less than k using
// binary search performed using compare-to.
- template <typename CompareTo>
- int binary_search_compare_to(
- const key_type &k, int s, int e, const CompareTo &comp) const {
- while (s != e) {
- int mid = (s + e) / 2;
- int c = comp(key(mid), k);
- if (c < 0) {
- s = mid + 1;
- } else if (c > 0) {
- e = mid;
- } else {
- // Need to return the first value whose key is not less than k, which
- // requires continuing the binary search. Note that we are guaranteed
- // that the result is an exact match because if "key(mid-1) < k" the
- // call to binary_search_compare_to() will return "mid".
- s = binary_search_compare_to(k, s, mid, comp);
- return s | kExactMatch;
+ template <typename K, typename CompareTo>
+ SearchResult<int, true> binary_search_impl(
+ const K &k, int s, int e, const CompareTo &comp,
+ std::true_type /* IsCompareTo */) const {
+ if (is_multi_container::value) {
+ MatchKind exact_match = MatchKind::kNe;
+ while (s != e) {
+ const int mid = (s + e) >> 1;
+ const absl::weak_ordering c = comp(key(mid), k);
+ if (c < 0) {
+ s = mid + 1;
+ } else {
+ e = mid;
+ if (c == 0) {
+ // Need to return the first value whose key is not less than k,
+ // which requires continuing the binary search if this is a
+ // multi-container.
+ exact_match = MatchKind::kEq;
+ }
+ }
+ }
+ return {s, exact_match};
+ } else { // Not a multi-container.
+ while (s != e) {
+ const int mid = (s + e) >> 1;
+ const absl::weak_ordering c = comp(key(mid), k);
+ if (c < 0) {
+ s = mid + 1;
+ } else if (c > 0) {
+ e = mid;
+ } else {
+ return {mid, MatchKind::kEq};
+ }
}
+ return {s, MatchKind::kNe};
}
- return s;
}
- // Inserts the value x at position i, shifting all existing values and
+ // Emplaces a value at position i, shifting all existing values and
// children at positions >= i to the right by 1.
- template<typename Value>
- void insert_value(int i, Value&& x);
+ template <typename... Args>
+ void emplace_value(size_type i, allocator_type *alloc, Args &&... args);
// Removes the value at position i, shifting all existing values and children
// at positions > i to the left by 1.
- void remove_value(int i);
+ void remove_value(int i, allocator_type *alloc);
+
+ // Removes the values at positions [i, i + to_erase), shifting all values
+ // after that range to the left by to_erase. Does not change children at all.
+ void remove_values_ignore_children(int i, int to_erase,
+ allocator_type *alloc);
// Rebalances a node with its right sibling.
- void rebalance_right_to_left(btree_node *sibling, int to_move);
- void rebalance_left_to_right(btree_node *sibling, int to_move);
+ void rebalance_right_to_left(int to_move, btree_node *right,
+ allocator_type *alloc);
+ void rebalance_left_to_right(int to_move, btree_node *right,
+ allocator_type *alloc);
// Splits a node, moving a portion of the node's values to its right sibling.
- void split(btree_node *sibling, int insert_position);
+ void split(int insert_position, btree_node *dest, allocator_type *alloc);
// Merges a node with its right sibling, moving all of the values and the
// delimiting key in the parent node onto itself.
- void merge(btree_node *sibling);
+ void merge(btree_node *sibling, allocator_type *alloc);
// Swap the contents of "this" and "src".
- void swap(btree_node *src);
+ void swap(btree_node *src, allocator_type *alloc);
-#ifdef NDEBUG
- static constexpr auto no_debug = true;
-#else
- static constexpr auto no_debug = false;
-#endif
// Node allocation/deletion routines.
- static btree_node* init_leaf(
- leaf_fields *f, btree_node *parent, int max_count) {
- btree_node *n = reinterpret_cast<btree_node*>(f);
- f->leaf = 1;
- f->position = 0;
- f->max_count = max_count;
- f->count = 0;
- f->parent = parent;
- if (!no_debug) {
- memset(&f->values, 0, max_count * sizeof(value_type));
- }
- return n;
- }
- static btree_node* init_internal(internal_fields *f, btree_node *parent) {
- btree_node *n = init_leaf(f, parent, kNodeValues);
- f->leaf = 0;
- if (!no_debug) {
- memset(f->children, 0, sizeof(f->children));
- }
+ static btree_node *init_leaf(btree_node *n, btree_node *parent,
+ int max_count) {
+ n->set_parent(parent);
+ n->set_position(0);
+ n->set_start(0);
+ n->set_count(0);
+ n->set_max_count(max_count);
+ absl::container_internal::SanitizerPoisonMemoryRegion(
+ n->slot(0), max_count * sizeof(slot_type));
return n;
}
- static btree_node* init_root(root_fields *f, btree_node *parent) {
- btree_node *n = init_internal(f, parent);
- f->rightmost = parent;
- f->size = parent->count();
+ static btree_node *init_internal(btree_node *n, btree_node *parent) {
+ init_leaf(n, parent, kNodeValues);
+ // Set `max_count` to a sentinel value to indicate that this node is
+ // internal.
+ n->set_max_count(kInternalNodeMaxCount);
+ absl::container_internal::SanitizerPoisonMemoryRegion(
+ &n->mutable_child(0), (kNodeValues + 1) * sizeof(btree_node *));
return n;
}
- void destroy() {
+ void destroy(allocator_type *alloc) {
for (int i = 0; i < count(); ++i) {
- value_destroy(i);
+ value_destroy(i, alloc);
}
}
- private:
- void value_init(int i) {
- new (&fields_.values[i]) mutable_value_type;
+ public:
+ // Exposed only for tests.
+ static bool testonly_uses_linear_node_search() {
+ return use_linear_search::value;
}
- void value_init(int i, const value_type &x) {
- new (&fields_.values[i]) mutable_value_type(x);
+
+ private:
+ template <typename... Args>
+ void value_init(const size_type i, allocator_type *alloc, Args &&... args) {
+ absl::container_internal::SanitizerUnpoisonObject(slot(i));
+ params_type::construct(alloc, slot(i), std::forward<Args>(args)...);
}
- void value_init(int i, value_type&& x) {
- new (&fields_.values[i]) mutable_value_type(std::move(x));
+ void value_destroy(const size_type i, allocator_type *alloc) {
+ params_type::destroy(alloc, slot(i));
+ absl::container_internal::SanitizerPoisonObject(slot(i));
}
- void value_destroy(int i) {
- fields_.values[i].~mutable_value_type();
+
+ // Move n values starting at value i in this node into the values starting at
+ // value j in node x.
+ void uninitialized_move_n(const size_type n, const size_type i,
+ const size_type j, btree_node *x,
+ allocator_type *alloc) {
+ absl::container_internal::SanitizerUnpoisonMemoryRegion(
+ x->slot(j), n * sizeof(slot_type));
+ for (slot_type *src = slot(i), *end = src + n, *dest = x->slot(j);
+ src != end; ++src, ++dest) {
+ params_type::construct(alloc, dest, src);
+ }
}
- private:
- root_fields fields_;
+ // Destroys a range of n values, starting at index i.
+ void value_destroy_n(const size_type i, const size_type n,
+ allocator_type *alloc) {
+ for (int j = 0; j < n; ++j) {
+ value_destroy(i + j, alloc);
+ }
+ }
- private:
- btree_node(const btree_node&);
- void operator=(const btree_node&);
+ template <typename P>
+ friend class btree;
+ template <typename N, typename R, typename P>
+ friend struct btree_iterator;
+ friend class BtreeNodePeer;
};
template <typename Node, typename Reference, typename Pointer>
struct btree_iterator {
- typedef typename Node::key_type key_type;
- typedef typename Node::size_type size_type;
- typedef typename Node::difference_type difference_type;
- typedef typename Node::params_type params_type;
-
- typedef Node node_type;
- typedef typename std::remove_const<Node>::type normal_node;
- typedef const Node const_node;
- typedef typename params_type::value_type value_type;
- typedef typename params_type::pointer normal_pointer;
- typedef typename params_type::reference normal_reference;
- typedef typename params_type::const_pointer const_pointer;
- typedef typename params_type::const_reference const_reference;
-
- typedef Pointer pointer;
- typedef Reference reference;
- typedef std::bidirectional_iterator_tag iterator_category;
-
- typedef btree_iterator<
- normal_node, normal_reference, normal_pointer> iterator;
- typedef btree_iterator<
- const_node, const_reference, const_pointer> const_iterator;
- typedef btree_iterator<Node, Reference, Pointer> self_type;
-
- btree_iterator()
- : node(NULL),
- position(-1) {
- }
- btree_iterator(Node *n, int p)
- : node(n),
- position(p) {
- }
- btree_iterator(const iterator &x)
- : node(x.node),
- position(x.position) {
- }
+ private:
+ using key_type = typename Node::key_type;
+ using size_type = typename Node::size_type;
+ using params_type = typename Node::params_type;
+
+ using node_type = Node;
+ using normal_node = typename std::remove_const<Node>::type;
+ using const_node = const Node;
+ using normal_pointer = typename params_type::pointer;
+ using normal_reference = typename params_type::reference;
+ using const_pointer = typename params_type::const_pointer;
+ using const_reference = typename params_type::const_reference;
+ using slot_type = typename params_type::slot_type;
+
+ using iterator =
+ btree_iterator<normal_node, normal_reference, normal_pointer>;
+ using const_iterator =
+ btree_iterator<const_node, const_reference, const_pointer>;
+
+ public:
+ // These aliases are public for std::iterator_traits.
+ using difference_type = typename Node::difference_type;
+ using value_type = typename params_type::value_type;
+ using pointer = Pointer;
+ using reference = Reference;
+ using iterator_category = std::bidirectional_iterator_tag;
+
+ btree_iterator() : node(nullptr), position(-1) {}
+ btree_iterator(Node *n, int p) : node(n), position(p) {}
+
+ // NOTE: this SFINAE allows for implicit conversions from iterator to
+ // const_iterator, but it specifically avoids defining copy constructors so
+ // that btree_iterator can be trivially copyable. This is for performance and
+ // binary size reasons.
+ template <typename N, typename R, typename P,
+ absl::enable_if_t<
+ std::is_same<btree_iterator<N, R, P>, iterator>::value &&
+ std::is_same<btree_iterator, const_iterator>::value,
+ int> = 0>
+ btree_iterator(const btree_iterator<N, R, P> &x) // NOLINT
+ : node(x.node), position(x.position) {}
+
+ private:
+ // This SFINAE allows explicit conversions from const_iterator to
+ // iterator, but also avoids defining a copy constructor.
+ // NOTE: the const_cast is safe because this constructor is only called by
+ // non-const methods and the container owns the nodes.
+ template <typename N, typename R, typename P,
+ absl::enable_if_t<
+ std::is_same<btree_iterator<N, R, P>, const_iterator>::value &&
+ std::is_same<btree_iterator, iterator>::value,
+ int> = 0>
+ explicit btree_iterator(const btree_iterator<N, R, P> &x)
+ : node(const_cast<node_type *>(x.node)), position(x.position) {}
// Increment/decrement the iterator.
void increment() {
}
increment_slow();
}
- void increment_by(int count);
void increment_slow();
void decrement() {
}
void decrement_slow();
+ public:
bool operator==(const const_iterator &x) const {
return node == x.node && position == x.position;
}
}
// Accessors for the key/value the iterator is pointing at.
- const key_type& key() const {
- return node->key(position);
- }
reference operator*() const {
return node->value(position);
}
return &node->value(position);
}
- self_type& operator++() {
+ btree_iterator& operator++() {
increment();
return *this;
}
- self_type& operator--() {
+ btree_iterator& operator--() {
decrement();
return *this;
}
- self_type operator++(int) {
- self_type tmp = *this;
+ btree_iterator operator++(int) {
+ btree_iterator tmp = *this;
++*this;
return tmp;
}
- self_type operator--(int) {
- self_type tmp = *this;
+ btree_iterator operator--(int) {
+ btree_iterator tmp = *this;
--*this;
return tmp;
}
+ private:
+ template <typename Params>
+ friend class btree;
+ template <typename Tree>
+ friend class btree_container;
+ template <typename Tree>
+ friend class btree_set_container;
+ template <typename Tree>
+ friend class btree_map_container;
+ template <typename Tree>
+ friend class btree_multiset_container;
+ template <typename N, typename R, typename P>
+ friend struct btree_iterator;
+ template <typename TreeType, typename CheckerType>
+ friend class base_checker;
+
+ const key_type &key() const { return node->key(position); }
+ slot_type *slot() { return node->slot(position); }
+
// The node in the tree the iterator is pointing at.
Node *node;
// The position within the node of the tree the iterator is pointing at.
+ // TODO(ezb): make this a field_type
int position;
};
-// Dispatch helper class for using btree::internal_locate with plain compare.
-struct btree_internal_locate_plain_compare {
- template <typename K, typename T, typename Iter>
- static std::pair<Iter, int> dispatch(const K &k, const T &t, Iter iter) {
- return t.internal_locate_plain_compare(k, iter);
- }
-};
+template <typename Params>
+class btree {
+ using node_type = btree_node<Params>;
+ using is_key_compare_to = typename Params::is_key_compare_to;
+
+ // We use a static empty node for the root/leftmost/rightmost of empty btrees
+ // in order to avoid branching in begin()/end().
+ struct alignas(node_type::Alignment()) EmptyNodeType : node_type {
+ using field_type = typename node_type::field_type;
+ node_type *parent;
+ field_type position = 0;
+ field_type start = 0;
+ field_type count = 0;
+ // max_count must be != kInternalNodeMaxCount (so that this node is regarded
+ // as a leaf node). max_count() is never called when the tree is empty.
+ field_type max_count = node_type::kInternalNodeMaxCount + 1;
+
+#ifdef _MSC_VER
+ // MSVC has constexpr code generations bugs here.
+ EmptyNodeType() : parent(this) {}
+#else
+ constexpr EmptyNodeType(node_type *p) : parent(p) {}
+#endif
+ };
-// Dispatch helper class for using btree::internal_locate with compare-to.
-struct btree_internal_locate_compare_to {
- template <typename K, typename T, typename Iter>
- static std::pair<Iter, int> dispatch(const K &k, const T &t, Iter iter) {
- return t.internal_locate_compare_to(k, iter);
+ static node_type *EmptyNode() {
+#ifdef _MSC_VER
+ static EmptyNodeType* empty_node = new EmptyNodeType;
+ // This assert fails on some other construction methods.
+ assert(empty_node->parent == empty_node);
+ return empty_node;
+#else
+ static constexpr EmptyNodeType empty_node(
+ const_cast<EmptyNodeType *>(&empty_node));
+ return const_cast<EmptyNodeType *>(&empty_node);
+#endif
}
-};
-
-template <typename Params>
-class btree : public Params::key_compare {
- typedef btree<Params> self_type;
- typedef btree_node<Params> node_type;
- typedef typename node_type::base_fields base_fields;
- typedef typename node_type::leaf_fields leaf_fields;
- typedef typename node_type::internal_fields internal_fields;
- typedef typename node_type::root_fields root_fields;
- static constexpr bool is_key_compare_to = Params::is_key_compare_to;
-
- friend class btree_internal_locate_plain_compare;
- friend class btree_internal_locate_compare_to;
- using internal_locate_type = std::conditional_t<
- is_key_compare_to,
- btree_internal_locate_compare_to,
- btree_internal_locate_plain_compare>;
enum {
kNodeValues = node_type::kNodeValues,
kMinNodeValues = kNodeValues / 2,
- kValueSize = node_type::kValueSize,
- kExactMatch = node_type::kExactMatch,
- kMatchMask = node_type::kMatchMask,
- };
-
- // A helper class to get the empty base class optimization for 0-size
- // allocators. Base is internal_allocator_type.
- // (e.g. empty_base_handle<internal_allocator_type, node_type*>). If Base is
- // 0-size, the compiler doesn't have to reserve any space for it and
- // sizeof(empty_base_handle) will simply be sizeof(Data). Google [empty base
- // class optimization] for more details.
- template <typename Base, typename Data>
- struct empty_base_handle : public Base {
- empty_base_handle(const Base &b, const Data &d)
- : Base(b),
- data(d) {
- }
- Data data;
};
struct node_stats {
- node_stats(ssize_t l, ssize_t i)
+ using size_type = typename Params::size_type;
+
+ node_stats(size_type l, size_type i)
: leaf_nodes(l),
internal_nodes(i) {
}
return *this;
}
- ssize_t leaf_nodes;
- ssize_t internal_nodes;
+ size_type leaf_nodes;
+ size_type internal_nodes;
};
public:
- typedef Params params_type;
- typedef typename Params::key_type key_type;
- typedef typename Params::data_type data_type;
- typedef typename Params::mapped_type mapped_type;
- typedef typename Params::value_type value_type;
- typedef typename Params::key_compare key_compare;
- typedef typename Params::pointer pointer;
- typedef typename Params::const_pointer const_pointer;
- typedef typename Params::reference reference;
- typedef typename Params::const_reference const_reference;
- typedef typename Params::size_type size_type;
- typedef typename Params::difference_type difference_type;
- typedef btree_iterator<node_type, reference, pointer> iterator;
- typedef typename iterator::const_iterator const_iterator;
- typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
- typedef std::reverse_iterator<iterator> reverse_iterator;
-
- typedef typename Params::allocator_type allocator_type;
- typedef typename allocator_type::template rebind<char>::other
- internal_allocator_type;
+ using key_type = typename Params::key_type;
+ using value_type = typename Params::value_type;
+ using size_type = typename Params::size_type;
+ using difference_type = typename Params::difference_type;
+ using key_compare = typename Params::key_compare;
+ using value_compare = typename Params::value_compare;
+ using allocator_type = typename Params::allocator_type;
+ using reference = typename Params::reference;
+ using const_reference = typename Params::const_reference;
+ using pointer = typename Params::pointer;
+ using const_pointer = typename Params::const_pointer;
+ using iterator = btree_iterator<node_type, reference, pointer>;
+ using const_iterator = typename iterator::const_iterator;
+ using reverse_iterator = std::reverse_iterator<iterator>;
+ using const_reverse_iterator = std::reverse_iterator<const_iterator>;
+ using node_handle_type = node_handle<Params, Params, allocator_type>;
+
+ // Internal types made public for use by btree_container types.
+ using params_type = Params;
+ using slot_type = typename Params::slot_type;
+
+ private:
+ // For use in copy_or_move_values_in_order.
+ const value_type &maybe_move_from_iterator(const_iterator x) { return *x; }
+ value_type &&maybe_move_from_iterator(iterator x) { return std::move(*x); }
+
+ // Copies or moves (depending on the template parameter) the values in
+ // x into this btree in their order in x. This btree must be empty before this
+ // method is called. This method is used in copy construction, copy
+ // assignment, and move assignment.
+ template <typename Btree>
+ void copy_or_move_values_in_order(Btree *x);
+
+ // Validates that various assumptions/requirements are true at compile time.
+ constexpr static bool static_assert_validation();
public:
- // Default constructor.
btree(const key_compare &comp, const allocator_type &alloc);
- // Copy constructor.
- btree(const self_type &x);
+ btree(const btree &x);
+ btree(btree &&x) noexcept
+ : root_(std::move(x.root_)),
+ rightmost_(absl::exchange(x.rightmost_, EmptyNode())),
+ size_(absl::exchange(x.size_, 0)) {
+ x.mutable_root() = EmptyNode();
+ }
- // Destructor.
~btree() {
+ // Put static_asserts in destructor to avoid triggering them before the type
+ // is complete.
+ static_assert(static_assert_validation(), "This call must be elided.");
clear();
}
- // Iterator routines.
+ // Assign the contents of x to *this.
+ btree &operator=(const btree &x);
+ btree &operator=(btree &&x) noexcept;
+
iterator begin() {
return iterator(leftmost(), 0);
}
const_iterator begin() const {
return const_iterator(leftmost(), 0);
}
- iterator end() {
- return iterator(rightmost(), rightmost() ? rightmost()->count() : 0);
- }
+ iterator end() { return iterator(rightmost_, rightmost_->count()); }
const_iterator end() const {
- return const_iterator(rightmost(), rightmost() ? rightmost()->count() : 0);
+ return const_iterator(rightmost_, rightmost_->count());
}
reverse_iterator rbegin() {
return reverse_iterator(end());
}
// Finds the first element whose key is not less than key.
- iterator lower_bound(const key_type &key) {
- return internal_end(
- internal_lower_bound(key, iterator(root(), 0)));
+ template <typename K>
+ iterator lower_bound(const K &key) {
+ return internal_end(internal_lower_bound(key));
}
- const_iterator lower_bound(const key_type &key) const {
- return internal_end(
- internal_lower_bound(key, const_iterator(root(), 0)));
+ template <typename K>
+ const_iterator lower_bound(const K &key) const {
+ return internal_end(internal_lower_bound(key));
}
// Finds the first element whose key is greater than key.
- iterator upper_bound(const key_type &key) {
- return internal_end(
- internal_upper_bound(key, iterator(root(), 0)));
+ template <typename K>
+ iterator upper_bound(const K &key) {
+ return internal_end(internal_upper_bound(key));
}
- const_iterator upper_bound(const key_type &key) const {
- return internal_end(
- internal_upper_bound(key, const_iterator(root(), 0)));
+ template <typename K>
+ const_iterator upper_bound(const K &key) const {
+ return internal_end(internal_upper_bound(key));
}
// Finds the range of values which compare equal to key. The first member of
// the returned pair is equal to lower_bound(key). The second member pair of
// the pair is equal to upper_bound(key).
- std::pair<iterator,iterator> equal_range(const key_type &key) {
- return std::make_pair(lower_bound(key), upper_bound(key));
+ template <typename K>
+ std::pair<iterator, iterator> equal_range(const K &key) {
+ return {lower_bound(key), upper_bound(key)};
}
- std::pair<const_iterator,const_iterator> equal_range(const key_type &key) const {
- return std::make_pair(lower_bound(key), upper_bound(key));
+ template <typename K>
+ std::pair<const_iterator, const_iterator> equal_range(const K &key) const {
+ return {lower_bound(key), upper_bound(key)};
}
- // Inserts a value into the btree only if it does not already exist. The
- // boolean return value indicates whether insertion succeeded or failed. The
- // ValuePointer type is used to avoid instatiating the value unless the key
- // is being inserted. Value is not dereferenced if the key already exists in
- // the btree. See btree_map::operator[].
- template <typename ValuePointer>
- std::pair<iterator,bool> insert_unique(const key_type &key, ValuePointer value);
-
// Inserts a value into the btree only if it does not already exist. The
// boolean return value indicates whether insertion succeeded or failed.
- std::pair<iterator,bool> insert_unique(const value_type &v) {
- return insert_unique(params_type::key(v), &v);
- }
+ // Requirement: if `key` already exists in the btree, does not consume `args`.
+ // Requirement: `key` is never referenced after consuming `args`.
+ template <typename... Args>
+ std::pair<iterator, bool> insert_unique(const key_type &key, Args &&... args);
- // Insert with hint. Check to see if the value should be placed immediately
- // before position in the tree. If it does, then the insertion will take
+ // Inserts with hint. Checks to see if the value should be placed immediately
+ // before `position` in the tree. If so, then the insertion will take
// amortized constant time. If not, the insertion will take amortized
- // logarithmic time as if a call to insert_unique(v) were made.
- template <typename Value>
- iterator insert_unique(iterator position, Value&& v);
+ // logarithmic time as if a call to insert_unique() were made.
+ // Requirement: if `key` already exists in the btree, does not consume `args`.
+ // Requirement: `key` is never referenced after consuming `args`.
+ template <typename... Args>
+ std::pair<iterator, bool> insert_hint_unique(iterator position,
+ const key_type &key,
+ Args &&... args);
// Insert a range of values into the btree.
template <typename InputIterator>
- void insert_unique(InputIterator b, InputIterator e);
+ void insert_iterator_unique(InputIterator b, InputIterator e);
- // Inserts a value into the btree. The ValuePointer type is used to avoid
- // instatiating the value unless the key is being inserted. Value is not
- // dereferenced if the key already exists in the btree. See
- // btree_map::operator[].
- template <typename ValuePointer>
- iterator insert_multi(const key_type &key, ValuePointer value);
+ // Inserts a value into the btree.
+ template <typename ValueType>
+ iterator insert_multi(const key_type &key, ValueType &&v);
// Inserts a value into the btree.
- iterator insert_multi(const value_type &v) {
- return insert_multi(params_type::key(v), &v);
+ template <typename ValueType>
+ iterator insert_multi(ValueType &&v) {
+ return insert_multi(params_type::key(v), std::forward<ValueType>(v));
}
// Insert with hint. Check to see if the value should be placed immediately
// before position in the tree. If it does, then the insertion will take
// amortized constant time. If not, the insertion will take amortized
// logarithmic time as if a call to insert_multi(v) were made.
- iterator insert_multi(iterator position, const value_type &v);
+ template <typename ValueType>
+ iterator insert_hint_multi(iterator position, ValueType &&v);
// Insert a range of values into the btree.
template <typename InputIterator>
- void insert_multi(InputIterator b, InputIterator e);
-
- void assign(const self_type &x);
+ void insert_iterator_multi(InputIterator b, InputIterator e);
// Erase the specified iterator from the btree. The iterator must be valid
// (i.e. not equal to end()). Return an iterator pointing to the node after
// the one that was erased (or end() if none exists).
+ // Requirement: does not read the value at `*iter`.
iterator erase(iterator iter);
- // Erases range. Returns the number of keys erased.
- int erase(iterator begin, iterator end);
+ // Erases range. Returns the number of keys erased and an iterator pointing
+ // to the element after the last erased element.
+ std::pair<size_type, iterator> erase(iterator begin, iterator end);
// Erases the specified key from the btree. Returns 1 if an element was
// erased and 0 otherwise.
- int erase_unique(const key_type &key);
+ template <typename K>
+ size_type erase_unique(const K &key);
// Erases all of the entries matching the specified key from the
// btree. Returns the number of elements erased.
- int erase_multi(const key_type &key);
+ template <typename K>
+ size_type erase_multi(const K &key);
// Finds the iterator corresponding to a key or returns end() if the key is
// not present.
- iterator find_unique(const key_type &key) {
- return internal_end(
- internal_find_unique(key, iterator(root(), 0)));
+ template <typename K>
+ iterator find(const K &key) {
+ return internal_end(internal_find(key));
}
- const_iterator find_unique(const key_type &key) const {
- return internal_end(
- internal_find_unique(key, const_iterator(root(), 0)));
- }
- iterator find_multi(const key_type &key) {
- return internal_end(
- internal_find_multi(key, iterator(root(), 0)));
- }
- const_iterator find_multi(const key_type &key) const {
- return internal_end(
- internal_find_multi(key, const_iterator(root(), 0)));
+ template <typename K>
+ const_iterator find(const K &key) const {
+ return internal_end(internal_find(key));
}
// Returns a count of the number of times the key appears in the btree.
- size_type count_unique(const key_type &key) const {
- const_iterator begin = internal_find_unique(
- key, const_iterator(root(), 0));
- if (!begin.node) {
+ template <typename K>
+ size_type count_unique(const K &key) const {
+ const iterator begin = internal_find(key);
+ if (begin.node == nullptr) {
// The key doesn't exist in the tree.
return 0;
}
return 1;
}
// Returns a count of the number of times the key appears in the btree.
- size_type count_multi(const key_type &key) const {
- return distance(lower_bound(key), upper_bound(key));
+ template <typename K>
+ size_type count_multi(const K &key) const {
+ const auto range = equal_range(key);
+ return std::distance(range.first, range.second);
}
// Clear the btree, deleting all of the values it contains.
void clear();
// Swap the contents of *this and x.
- void swap(self_type &x);
-
- // Assign the contents of x to *this.
- self_type& operator=(const self_type &x) {
- if (&x == this) {
- // Don't copy onto ourselves.
- return *this;
- }
- assign(x);
- return *this;
- }
+ void swap(btree &x);
- key_compare* mutable_key_comp() {
- return this;
- }
- const key_compare& key_comp() const {
- return *this;
+ const key_compare &key_comp() const noexcept {
+ return root_.template get<0>();
}
- bool compare_keys(const key_type &x, const key_type &y) const {
- return btree_compare_keys(key_comp(), x, y);
+ template <typename K, typename LK>
+ bool compare_keys(const K &x, const LK &y) const {
+ return compare_internal::compare_result_as_less_than(key_comp()(x, y));
}
- // Dump the btree to the specified ostream. Requires that operator<< is
- // defined for Key and Value.
- void dump(std::ostream &os) const {
- if (root() != NULL) {
- internal_dump(os, root(), 0);
- }
- }
+ value_compare value_comp() const { return value_compare(key_comp()); }
// Verifies the structure of the btree.
void verify() const;
- // Size routines. Note that empty() is slightly faster than doing size()==0.
- size_type size() const {
- if (empty()) return 0;
- if (root()->leaf()) return root()->count();
- return root()->size();
- }
- size_type max_size() const { return std::numeric_limits<size_type>::max(); }
- bool empty() const { return root() == NULL; }
+ // Size routines.
+ size_type size() const { return size_; }
+ size_type max_size() const { return (std::numeric_limits<size_type>::max)(); }
+ bool empty() const { return size_ == 0; }
// The height of the btree. An empty tree will have height 0.
size_type height() const {
size_type h = 0;
- if (root()) {
+ if (!empty()) {
// Count the length of the chain from the leftmost node up to the
// root. We actually count from the root back around to the level below
// the root, but the calculation is the same because of the circularity
node_stats stats = internal_stats(root());
if (stats.leaf_nodes == 1 && stats.internal_nodes == 0) {
return sizeof(*this) +
- sizeof(base_fields) + root()->max_count() * sizeof(value_type);
+ node_type::LeafSize(root()->max_count());
} else {
return sizeof(*this) +
- sizeof(root_fields) - sizeof(internal_fields) +
- stats.leaf_nodes * sizeof(leaf_fields) +
- stats.internal_nodes * sizeof(internal_fields);
+ stats.leaf_nodes * node_type::LeafSize() +
+ stats.internal_nodes * node_type::InternalSize();
}
}
// Returns the number of bytes per value on a leaf node that is 75%
// full. Experimentally, this matches up nicely with the computed number of
// bytes per value in trees that had their values inserted in random order.
- return sizeof(leaf_fields) / (kNodeValues * 0.75);
+ return node_type::LeafSize() / (kNodeValues * 0.75);
}
// The fullness of the btree. Computed as the number of elements in the btree
// divided by the maximum number of elements a tree with the current number
// of nodes could hold. A value of 1 indicates perfect space
// utilization. Smaller values indicate space wastage.
+ // Returns 0 for empty trees.
double fullness() const {
- return double(size()) / (nodes() * kNodeValues);
+ if (empty()) return 0.0;
+ return static_cast<double>(size()) / (nodes() * kNodeValues);
}
// The overhead of the btree structure in bytes per node. Computed as the
// total number of bytes used by the btree minus the number of bytes used for
// storing elements divided by the number of elements.
+ // Returns 0 for empty trees.
double overhead() const {
- if (empty()) {
- return 0.0;
- }
- return (bytes_used() - size() * kValueSize) / double(size());
+ if (empty()) return 0.0;
+ return (bytes_used() - size() * sizeof(value_type)) /
+ static_cast<double>(size());
+ }
+
+ // The allocator used by the btree.
+ allocator_type get_allocator() const {
+ return allocator();
}
private:
// Internal accessor routines.
- node_type* root() { return root_.data; }
- const node_type* root() const { return root_.data; }
- node_type** mutable_root() { return &root_.data; }
-
- // The rightmost node is stored in the root node.
- node_type* rightmost() {
- return (!root() || root()->leaf()) ? root() : root()->rightmost();
- }
- const node_type* rightmost() const {
- return (!root() || root()->leaf()) ? root() : root()->rightmost();
- }
- node_type** mutable_rightmost() { return root()->mutable_rightmost(); }
+ node_type *root() { return root_.template get<2>(); }
+ const node_type *root() const { return root_.template get<2>(); }
+ node_type *&mutable_root() noexcept { return root_.template get<2>(); }
+ key_compare *mutable_key_comp() noexcept { return &root_.template get<0>(); }
// The leftmost node is stored as the parent of the root node.
- node_type* leftmost() { return root() ? root()->parent() : NULL; }
- const node_type* leftmost() const { return root() ? root()->parent() : NULL; }
-
- // The size of the tree is stored in the root node.
- size_type* mutable_size() { return root()->mutable_size(); }
+ node_type *leftmost() { return root()->parent(); }
+ const node_type *leftmost() const { return root()->parent(); }
// Allocator routines.
- internal_allocator_type* mutable_internal_allocator() {
- return static_cast<internal_allocator_type*>(&root_);
+ allocator_type *mutable_allocator() noexcept {
+ return &root_.template get<1>();
+ }
+ const allocator_type &allocator() const noexcept {
+ return root_.template get<1>();
}
- const internal_allocator_type& internal_allocator() const {
- return *static_cast<const internal_allocator_type*>(&root_);
+
+ // Allocates a correctly aligned node of at least size bytes using the
+ // allocator.
+ node_type *allocate(const size_type size) {
+ return reinterpret_cast<node_type *>(
+ absl::container_internal::Allocate<node_type::Alignment()>(
+ mutable_allocator(), size));
}
// Node creation/deletion routines.
node_type* new_internal_node(node_type *parent) {
- internal_fields *p = reinterpret_cast<internal_fields*>(
- mutable_internal_allocator()->allocate(sizeof(internal_fields)));
+ node_type *p = allocate(node_type::InternalSize());
return node_type::init_internal(p, parent);
}
- node_type* new_internal_root_node() {
- root_fields *p = reinterpret_cast<root_fields*>(
- mutable_internal_allocator()->allocate(sizeof(root_fields)));
- return node_type::init_root(p, root()->parent());
- }
node_type* new_leaf_node(node_type *parent) {
- leaf_fields *p = reinterpret_cast<leaf_fields*>(
- mutable_internal_allocator()->allocate(sizeof(leaf_fields)));
+ node_type *p = allocate(node_type::LeafSize());
return node_type::init_leaf(p, parent, kNodeValues);
}
- node_type* new_leaf_root_node(int max_count) {
- leaf_fields *p = reinterpret_cast<leaf_fields*>(
- mutable_internal_allocator()->allocate(
- sizeof(base_fields) + max_count * sizeof(value_type)));
- return node_type::init_leaf(p, reinterpret_cast<node_type*>(p), max_count);
+ node_type *new_leaf_root_node(const int max_count) {
+ node_type *p = allocate(node_type::LeafSize(max_count));
+ return node_type::init_leaf(p, p, max_count);
}
- void delete_internal_node(node_type *node) {
- node->destroy();
- ceph_assert(node != root());
- mutable_internal_allocator()->deallocate(
- reinterpret_cast<char*>(node), sizeof(internal_fields));
+
+ // Deletion helper routines.
+ void erase_same_node(iterator begin, iterator end);
+ iterator erase_from_leaf_node(iterator begin, size_type to_erase);
+ iterator rebalance_after_delete(iterator iter);
+
+ // Deallocates a node of a certain size in bytes using the allocator.
+ void deallocate(const size_type size, node_type *node) {
+ absl::container_internal::Deallocate<node_type::Alignment()>(
+ mutable_allocator(), node, size);
}
- void delete_internal_root_node() {
- root()->destroy();
- mutable_internal_allocator()->deallocate(
- reinterpret_cast<char*>(root()), sizeof(root_fields));
+
+ void delete_internal_node(node_type *node) {
+ node->destroy(mutable_allocator());
+ deallocate(node_type::InternalSize(), node);
}
void delete_leaf_node(node_type *node) {
- node->destroy();
- mutable_internal_allocator()->deallocate(
- reinterpret_cast<char*>(node),
- sizeof(base_fields) + node->max_count() * sizeof(value_type));
+ node->destroy(mutable_allocator());
+ deallocate(node_type::LeafSize(node->max_count()), node);
}
// Rebalances or splits the node iter points to.
void try_shrink();
iterator internal_end(iterator iter) {
- return iter.node ? iter : end();
+ return iter.node != nullptr ? iter : end();
}
const_iterator internal_end(const_iterator iter) const {
- return iter.node ? iter : end();
+ return iter.node != nullptr ? iter : end();
}
- // Inserts a value into the btree immediately before iter. Requires that
+ // Emplaces a value into the btree immediately before iter. Requires that
// key(v) <= iter.key() and (--iter).key() <= key(v).
- template<typename Value>
- iterator internal_insert(iterator iter, Value&& v);
+ template <typename... Args>
+ iterator internal_emplace(iterator iter, Args &&... args);
// Returns an iterator pointing to the first value >= the value "iter" is
// pointing at. Note that "iter" might be pointing to an invalid location as
// iter.position == iter.node->count(). This routine simply moves iter up in
// the tree to a valid location.
+ // Requires: iter.node is non-null.
template <typename IterType>
static IterType internal_last(IterType iter);
// Returns an iterator pointing to the leaf position at which key would
// reside in the tree. We provide 2 versions of internal_locate. The first
- // version (internal_locate_plain_compare) always returns 0 for the second
- // field of the pair. The second version (internal_locate_compare_to) is for
- // the key-compare-to specialization and returns either kExactMatch (if the
- // key was found in the tree) or -kExactMatch (if it wasn't) in the second
- // field of the pair. The compare_to specialization allows the caller to
- // avoid a subsequent comparison to determine if an exact match was made,
- // speeding up string keys.
- template <typename IterType>
- std::pair<IterType, int> internal_locate(
- const key_type &key, IterType iter) const;
- template <typename IterType>
- std::pair<IterType, int> internal_locate_plain_compare(
- const key_type &key, IterType iter) const;
- template <typename IterType>
- std::pair<IterType, int> internal_locate_compare_to(
- const key_type &key, IterType iter) const;
+ // version uses a less-than comparator and is incapable of distinguishing when
+ // there is an exact match. The second version is for the key-compare-to
+ // specialization and distinguishes exact matches. The key-compare-to
+ // specialization allows the caller to avoid a subsequent comparison to
+ // determine if an exact match was made, which is important for keys with
+ // expensive comparison, such as strings.
+ template <typename K>
+ SearchResult<iterator, is_key_compare_to::value> internal_locate(
+ const K &key) const;
+
+ template <typename K>
+ SearchResult<iterator, false> internal_locate_impl(
+ const K &key, std::false_type /* IsCompareTo */) const;
+
+ template <typename K>
+ SearchResult<iterator, true> internal_locate_impl(
+ const K &key, std::true_type /* IsCompareTo */) const;
// Internal routine which implements lower_bound().
- template <typename IterType>
- IterType internal_lower_bound(
- const key_type &key, IterType iter) const;
+ template <typename K>
+ iterator internal_lower_bound(const K &key) const;
// Internal routine which implements upper_bound().
- template <typename IterType>
- IterType internal_upper_bound(
- const key_type &key, IterType iter) const;
+ template <typename K>
+ iterator internal_upper_bound(const K &key) const;
- // Internal routine which implements find_unique().
- template <typename IterType>
- IterType internal_find_unique(
- const key_type &key, IterType iter) const;
-
- // Internal routine which implements find_multi().
- template <typename IterType>
- IterType internal_find_multi(
- const key_type &key, IterType iter) const;
+ // Internal routine which implements find().
+ template <typename K>
+ iterator internal_find(const K &key) const;
// Deletes a node and all of its children.
void internal_clear(node_type *node);
- // Dumps a node and all of its children to the specified ostream.
- void internal_dump(std::ostream &os, const node_type *node, int level) const;
-
// Verifies the tree structure of node.
int internal_verify(const node_type *node,
const key_type *lo, const key_type *hi) const;
node_stats internal_stats(const node_type *node) const {
- if (!node) {
+ // The root can be a static empty node.
+ if (node == nullptr || (node == root() && empty())) {
return node_stats(0, 0);
}
if (node->leaf()) {
return res;
}
- private:
- empty_base_handle<internal_allocator_type, node_type*> root_;
+ public:
+ // Exposed only for tests.
+ static bool testonly_uses_linear_node_search() {
+ return node_type::testonly_uses_linear_node_search();
+ }
private:
- // A never instantiated helper function that returns big_ if we have a
- // key-compare-to functor or if R is bool and small_ otherwise.
- template <typename R>
- static std::conditional_t<
- (is_key_compare_to ?
- std::is_same_v<R, int> :
- std::is_same_v<R, bool>),
- big_, small_> key_compare_checker(R);
-
- // A never instantiated helper function that returns the key comparison
- // functor.
- static key_compare key_compare_helper();
-
- // Verify that key_compare returns a bool. This is similar to the way
- // is_convertible in base/type_traits.h works. Note that key_compare_checker
- // is never actually invoked. The compiler will select which
- // key_compare_checker() to instantiate and then figure out the size of the
- // return type of key_compare_checker() at compile time which we then check
- // against the sizeof of big_.
- static_assert(
- sizeof(key_compare_checker(key_compare_helper()(key_type(), key_type()))) ==
- sizeof(big_),
- "key comparison function must return bool");
-
- // Note: We insist on kTargetValues, which is computed from
- // Params::kTargetNodeSize, must fit the base_fields::field_type.
- static_assert(kNodeValues <
- (1 << (8 * sizeof(typename base_fields::field_type))),
- "target node size too large");
-
- // Test the assumption made in setting kNodeValueSpace.
- static_assert(sizeof(base_fields) >= 2 * sizeof(void*),
- "node space assumption incorrect");
+ // We use compressed tuple in order to save space because key_compare and
+ // allocator_type are usually empty.
+ absl::container_internal::CompressedTuple<key_compare, allocator_type,
+ node_type *>
+ root_;
+
+ // A pointer to the rightmost node. Note that the leftmost node is stored as
+ // the root's parent.
+ node_type *rightmost_;
+
+ // Number of values.
+ size_type size_;
};
////
// btree_node methods
template <typename P>
-template <typename Value>
-inline void btree_node<P>::insert_value(int i, Value&& x) {
- ceph_assert(i <= count());
- value_init(count(), std::forward<Value>(x));
- for (int j = count(); j > i; --j) {
- value_swap(j, this, j - 1);
- }
+template <typename... Args>
+inline void btree_node<P>::emplace_value(const size_type i,
+ allocator_type *alloc,
+ Args &&... args) {
+ assert(i <= count());
+ // Shift old values to create space for new value and then construct it in
+ // place.
+ if (i < count()) {
+ value_init(count(), alloc, slot(count() - 1));
+ for (size_type j = count() - 1; j > i; --j)
+ params_type::move(alloc, slot(j - 1), slot(j));
+ value_destroy(i, alloc);
+ }
+ value_init(i, alloc, std::forward<Args>(args)...);
set_count(count() + 1);
- if (!leaf()) {
- ++i;
- for (int j = count(); j > i; --j) {
- *mutable_child(j) = child(j - 1);
- child(j)->set_position(j);
+ if (!leaf() && count() > i + 1) {
+ for (int j = count(); j > i + 1; --j) {
+ set_child(j, child(j - 1));
}
- *mutable_child(i) = NULL;
+ clear_child(i + 1);
}
}
template <typename P>
-inline void btree_node<P>::remove_value(int i) {
- if (!leaf()) {
- ceph_assert(child(i + 1)->count() == 0);
- for (int j = i + 1; j < count(); ++j) {
- *mutable_child(j) = child(j + 1);
- child(j)->set_position(j);
+inline void btree_node<P>::remove_value(const int i, allocator_type *alloc) {
+ if (!leaf() && count() > i + 1) {
+ assert(child(i + 1)->count() == 0);
+ for (size_type j = i + 1; j < count(); ++j) {
+ set_child(j, child(j + 1));
}
- *mutable_child(count()) = NULL;
+ clear_child(count());
}
- set_count(count() - 1);
- for (; i < count(); ++i) {
- value_swap(i, this, i + 1);
- }
- value_destroy(i);
+ remove_values_ignore_children(i, /*to_erase=*/1, alloc);
}
template <typename P>
-void btree_node<P>::rebalance_right_to_left(btree_node *src, int to_move) {
- ceph_assert(parent() == src->parent());
- ceph_assert(position() + 1 == src->position());
- ceph_assert(src->count() >= count());
- ceph_assert(to_move >= 1);
- ceph_assert(to_move <= src->count());
+inline void btree_node<P>::remove_values_ignore_children(
+ const int i, const int to_erase, allocator_type *alloc) {
+ params_type::move(alloc, slot(i + to_erase), slot(count()), slot(i));
+ value_destroy_n(count() - to_erase, to_erase, alloc);
+ set_count(count() - to_erase);
+}
- // Make room in the left node for the new values.
- for (int i = 0; i < to_move; ++i) {
- value_init(i + count());
- }
+template <typename P>
+void btree_node<P>::rebalance_right_to_left(const int to_move,
+ btree_node *right,
+ allocator_type *alloc) {
+ assert(parent() == right->parent());
+ assert(position() + 1 == right->position());
+ assert(right->count() >= count());
+ assert(to_move >= 1);
+ assert(to_move <= right->count());
- // Move the delimiting value to the left node and the new delimiting value
- // from the right node.
- value_swap(count(), parent(), position());
- parent()->value_swap(position(), src, to_move - 1);
+ // 1) Move the delimiting value in the parent to the left node.
+ value_init(count(), alloc, parent()->slot(position()));
- // Move the values from the right to the left node.
- for (int i = 1; i < to_move; ++i) {
- value_swap(count() + i, src, i - 1);
- }
- // Shift the values in the right node to their correct position.
- for (int i = to_move; i < src->count(); ++i) {
- src->value_swap(i - to_move, src, i);
- }
- for (int i = 1; i <= to_move; ++i) {
- src->value_destroy(src->count() - i);
- }
+ // 2) Move the (to_move - 1) values from the right node to the left node.
+ right->uninitialized_move_n(to_move - 1, 0, count() + 1, this, alloc);
+
+ // 3) Move the new delimiting value to the parent from the right node.
+ params_type::move(alloc, right->slot(to_move - 1),
+ parent()->slot(position()));
+
+ // 4) Shift the values in the right node to their correct position.
+ params_type::move(alloc, right->slot(to_move), right->slot(right->count()),
+ right->slot(0));
+
+ // 5) Destroy the now-empty to_move entries in the right node.
+ right->value_destroy_n(right->count() - to_move, to_move, alloc);
if (!leaf()) {
// Move the child pointers from the right to the left node.
for (int i = 0; i < to_move; ++i) {
- set_child(1 + count() + i, src->child(i));
+ init_child(count() + i + 1, right->child(i));
}
- for (int i = 0; i <= src->count() - to_move; ++i) {
- ceph_assert(i + to_move <= src->max_count());
- src->set_child(i, src->child(i + to_move));
- *src->mutable_child(i + to_move) = NULL;
+ for (int i = 0; i <= right->count() - to_move; ++i) {
+ assert(i + to_move <= right->max_count());
+ right->init_child(i, right->child(i + to_move));
+ right->clear_child(i + to_move);
}
}
- // Fixup the counts on the src and dest nodes.
+ // Fixup the counts on the left and right nodes.
set_count(count() + to_move);
- src->set_count(src->count() - to_move);
+ right->set_count(right->count() - to_move);
}
template <typename P>
-void btree_node<P>::rebalance_left_to_right(btree_node *dest, int to_move) {
- ceph_assert(parent() == dest->parent());
- ceph_assert(position() + 1 == dest->position());
- ceph_assert(count() >= dest->count());
- ceph_assert(to_move >= 1);
- ceph_assert(to_move <= count());
+void btree_node<P>::rebalance_left_to_right(const int to_move,
+ btree_node *right,
+ allocator_type *alloc) {
+ assert(parent() == right->parent());
+ assert(position() + 1 == right->position());
+ assert(count() >= right->count());
+ assert(to_move >= 1);
+ assert(to_move <= count());
+
+ // Values in the right node are shifted to the right to make room for the
+ // new to_move values. Then, the delimiting value in the parent and the
+ // other (to_move - 1) values in the left node are moved into the right node.
+ // Lastly, a new delimiting value is moved from the left node into the
+ // parent, and the remaining empty left node entries are destroyed.
+
+ if (right->count() >= to_move) {
+ // The original location of the right->count() values are sufficient to hold
+ // the new to_move entries from the parent and left node.
+
+ // 1) Shift existing values in the right node to their correct positions.
+ right->uninitialized_move_n(to_move, right->count() - to_move,
+ right->count(), right, alloc);
+ for (slot_type *src = right->slot(right->count() - to_move - 1),
+ *dest = right->slot(right->count() - 1),
+ *end = right->slot(0);
+ src >= end; --src, --dest) {
+ params_type::move(alloc, src, dest);
+ }
+
+ // 2) Move the delimiting value in the parent to the right node.
+ params_type::move(alloc, parent()->slot(position()),
+ right->slot(to_move - 1));
+
+ // 3) Move the (to_move - 1) values from the left node to the right node.
+ params_type::move(alloc, slot(count() - (to_move - 1)), slot(count()),
+ right->slot(0));
+ } else {
+ // The right node does not have enough initialized space to hold the new
+ // to_move entries, so part of them will move to uninitialized space.
- // Make room in the right node for the new values.
- for (int i = 0; i < to_move; ++i) {
- dest->value_init(i + dest->count());
- }
- for (int i = dest->count() - 1; i >= 0; --i) {
- dest->value_swap(i, dest, i + to_move);
- }
+ // 1) Shift existing values in the right node to their correct positions.
+ right->uninitialized_move_n(right->count(), 0, to_move, right, alloc);
- // Move the delimiting value to the right node and the new delimiting value
- // from the left node.
- dest->value_swap(to_move - 1, parent(), position());
- parent()->value_swap(position(), this, count() - to_move);
- value_destroy(count() - to_move);
+ // 2) Move the delimiting value in the parent to the right node.
+ right->value_init(to_move - 1, alloc, parent()->slot(position()));
- // Move the values from the left to the right node.
- for (int i = 1; i < to_move; ++i) {
- value_swap(count() - to_move + i, dest, i - 1);
- value_destroy(count() - to_move + i);
+ // 3) Move the (to_move - 1) values from the left node to the right node.
+ const size_type uninitialized_remaining = to_move - right->count() - 1;
+ uninitialized_move_n(uninitialized_remaining,
+ count() - uninitialized_remaining, right->count(),
+ right, alloc);
+ params_type::move(alloc, slot(count() - (to_move - 1)),
+ slot(count() - uninitialized_remaining), right->slot(0));
}
+ // 4) Move the new delimiting value to the parent from the left node.
+ params_type::move(alloc, slot(count() - to_move), parent()->slot(position()));
+
+ // 5) Destroy the now-empty to_move entries in the left node.
+ value_destroy_n(count() - to_move, to_move, alloc);
+
if (!leaf()) {
// Move the child pointers from the left to the right node.
- for (int i = dest->count(); i >= 0; --i) {
- dest->set_child(i + to_move, dest->child(i));
- *dest->mutable_child(i) = NULL;
+ for (int i = right->count(); i >= 0; --i) {
+ right->init_child(i + to_move, right->child(i));
+ right->clear_child(i);
}
for (int i = 1; i <= to_move; ++i) {
- dest->set_child(i - 1, child(count() - to_move + i));
- *mutable_child(count() - to_move + i) = NULL;
+ right->init_child(i - 1, child(count() - to_move + i));
+ clear_child(count() - to_move + i);
}
}
- // Fixup the counts on the src and dest nodes.
+ // Fixup the counts on the left and right nodes.
set_count(count() - to_move);
- dest->set_count(dest->count() + to_move);
+ right->set_count(right->count() + to_move);
}
template <typename P>
-void btree_node<P>::split(btree_node *dest, int insert_position) {
- ceph_assert(dest->count() == 0);
+void btree_node<P>::split(const int insert_position, btree_node *dest,
+ allocator_type *alloc) {
+ assert(dest->count() == 0);
+ assert(max_count() == kNodeValues);
// We bias the split based on the position being inserted. If we're
// inserting at the beginning of the left node then bias the split to put
// right node then bias the split to put more values on the left node.
if (insert_position == 0) {
dest->set_count(count() - 1);
- } else if (insert_position == max_count()) {
+ } else if (insert_position == kNodeValues) {
dest->set_count(0);
} else {
dest->set_count(count() / 2);
}
set_count(count() - dest->count());
- ceph_assert(count() >= 1);
+ assert(count() >= 1);
// Move values from the left sibling to the right sibling.
- for (int i = 0; i < dest->count(); ++i) {
- dest->value_init(i);
- value_swap(count() + i, dest, i);
- value_destroy(count() + i);
- }
+ uninitialized_move_n(dest->count(), count(), 0, dest, alloc);
+
+ // Destroy the now-empty entries in the left node.
+ value_destroy_n(count(), dest->count(), alloc);
// The split key is the largest value in the left sibling.
set_count(count() - 1);
- parent()->insert_value(position(), value_type());
- value_swap(count(), parent(), position());
- value_destroy(count());
- parent()->set_child(position() + 1, dest);
+ parent()->emplace_value(position(), alloc, slot(count()));
+ value_destroy(count(), alloc);
+ parent()->init_child(position() + 1, dest);
if (!leaf()) {
for (int i = 0; i <= dest->count(); ++i) {
- ceph_assert(child(count() + i + 1) != NULL);
- dest->set_child(i, child(count() + i + 1));
- *mutable_child(count() + i + 1) = NULL;
+ assert(child(count() + i + 1) != nullptr);
+ dest->init_child(i, child(count() + i + 1));
+ clear_child(count() + i + 1);
}
}
}
template <typename P>
-void btree_node<P>::merge(btree_node *src) {
- ceph_assert(parent() == src->parent());
- ceph_assert(position() + 1 == src->position());
+void btree_node<P>::merge(btree_node *src, allocator_type *alloc) {
+ assert(parent() == src->parent());
+ assert(position() + 1 == src->position());
// Move the delimiting value to the left node.
- value_init(count());
- value_swap(count(), parent(), position());
+ value_init(count(), alloc, parent()->slot(position()));
// Move the values from the right to the left node.
- for (int i = 0; i < src->count(); ++i) {
- value_init(1 + count() + i);
- value_swap(1 + count() + i, src, i);
- src->value_destroy(i);
- }
+ src->uninitialized_move_n(src->count(), 0, count() + 1, this, alloc);
+
+ // Destroy the now-empty entries in the right node.
+ src->value_destroy_n(0, src->count(), alloc);
if (!leaf()) {
// Move the child pointers from the right to the left node.
for (int i = 0; i <= src->count(); ++i) {
- set_child(1 + count() + i, src->child(i));
- *src->mutable_child(i) = NULL;
+ init_child(count() + i + 1, src->child(i));
+ src->clear_child(i);
}
}
src->set_count(0);
// Remove the value on the parent node.
- parent()->remove_value(position());
+ parent()->remove_value(position(), alloc);
}
template <typename P>
-void btree_node<P>::swap(btree_node *x) {
- ceph_assert(leaf() == x->leaf());
+void btree_node<P>::swap(btree_node *x, allocator_type *alloc) {
+ using std::swap;
+ assert(leaf() == x->leaf());
- // Swap the values.
- for (int i = count(); i < x->count(); ++i) {
- value_init(i);
- }
- for (int i = x->count(); i < count(); ++i) {
- x->value_init(i);
- }
- int n = std::max(count(), x->count());
- for (int i = 0; i < n; ++i) {
- value_swap(i, x, i);
+ // Determine which is the smaller/larger node.
+ btree_node *smaller = this, *larger = x;
+ if (smaller->count() > larger->count()) {
+ swap(smaller, larger);
}
- for (int i = count(); i < x->count(); ++i) {
- x->value_destroy(i);
- }
- for (int i = x->count(); i < count(); ++i) {
- value_destroy(i);
+
+ // Swap the values.
+ for (slot_type *a = smaller->slot(0), *b = larger->slot(0),
+ *end = a + smaller->count();
+ a != end; ++a, ++b) {
+ params_type::swap(alloc, a, b);
}
+ // Move values that can't be swapped.
+ const size_type to_move = larger->count() - smaller->count();
+ larger->uninitialized_move_n(to_move, smaller->count(), smaller->count(),
+ smaller, alloc);
+ larger->value_destroy_n(smaller->count(), to_move, alloc);
+
if (!leaf()) {
// Swap the child pointers.
- for (int i = 0; i <= n; ++i) {
- btree_swap_helper(*mutable_child(i), *x->mutable_child(i));
- }
- for (int i = 0; i <= count(); ++i) {
- x->child(i)->fields_.parent = x;
+ std::swap_ranges(&smaller->mutable_child(0),
+ &smaller->mutable_child(smaller->count() + 1),
+ &larger->mutable_child(0));
+ // Update swapped children's parent pointers.
+ int i = 0;
+ for (; i <= smaller->count(); ++i) {
+ smaller->child(i)->set_parent(smaller);
+ larger->child(i)->set_parent(larger);
}
- for (int i = 0; i <= x->count(); ++i) {
- child(i)->fields_.parent = this;
+ // Move the child pointers that couldn't be swapped.
+ for (; i <= larger->count(); ++i) {
+ smaller->init_child(i, larger->child(i));
+ larger->clear_child(i);
}
}
// Swap the counts.
- btree_swap_helper(fields_.count, x->fields_.count);
+ swap(mutable_count(), x->mutable_count());
}
////
template <typename N, typename R, typename P>
void btree_iterator<N, R, P>::increment_slow() {
if (node->leaf()) {
- ceph_assert(position >= node->count());
- self_type save(*this);
+ assert(position >= node->count());
+ btree_iterator save(*this);
while (position == node->count() && !node->is_root()) {
- ceph_assert(node->parent()->child(node->position()) == node);
+ assert(node->parent()->child(node->position()) == node);
position = node->position();
node = node->parent();
}
*this = save;
}
} else {
- ceph_assert(position < node->count());
+ assert(position < node->count());
node = node->child(position + 1);
while (!node->leaf()) {
node = node->child(0);
}
}
-template <typename N, typename R, typename P>
-void btree_iterator<N, R, P>::increment_by(int count) {
- while (count > 0) {
- if (node->leaf()) {
- int rest = node->count() - position;
- position += std::min(rest, count);
- count = count - rest;
- if (position < node->count()) {
- return;
- }
- } else {
- --count;
- }
- increment_slow();
- }
-}
-
template <typename N, typename R, typename P>
void btree_iterator<N, R, P>::decrement_slow() {
if (node->leaf()) {
- ceph_assert(position <= -1);
- self_type save(*this);
+ assert(position <= -1);
+ btree_iterator save(*this);
while (position < 0 && !node->is_root()) {
- ceph_assert(node->parent()->child(node->position()) == node);
+ assert(node->parent()->child(node->position()) == node);
position = node->position() - 1;
node = node->parent();
}
*this = save;
}
} else {
- ceph_assert(position >= 0);
+ assert(position >= 0);
node = node->child(position);
while (!node->leaf()) {
node = node->child(node->count());
////
// btree methods
template <typename P>
-btree<P>::btree(const key_compare &comp, const allocator_type &alloc)
- : key_compare(comp),
- root_(alloc, NULL) {
+template <typename Btree>
+void btree<P>::copy_or_move_values_in_order(Btree *x) {
+ static_assert(std::is_same<btree, Btree>::value ||
+ std::is_same<const btree, Btree>::value,
+ "Btree type must be same or const.");
+ assert(empty());
+
+ // We can avoid key comparisons because we know the order of the
+ // values is the same order we'll store them in.
+ auto iter = x->begin();
+ if (iter == x->end()) return;
+ insert_multi(maybe_move_from_iterator(iter));
+ ++iter;
+ for (; iter != x->end(); ++iter) {
+ // If the btree is not empty, we can just insert the new value at the end
+ // of the tree.
+ internal_emplace(end(), maybe_move_from_iterator(iter));
+ }
+}
+
+template <typename P>
+constexpr bool btree<P>::static_assert_validation() {
+ static_assert(std::is_nothrow_copy_constructible<key_compare>::value,
+ "Key comparison must be nothrow copy constructible");
+ static_assert(std::is_nothrow_copy_constructible<allocator_type>::value,
+ "Allocator must be nothrow copy constructible");
+ static_assert(type_traits_internal::is_trivially_copyable<iterator>::value,
+ "iterator not trivially copyable.");
+
+ // Note: We assert that kTargetValues, which is computed from
+ // Params::kTargetNodeSize, must fit the node_type::field_type.
+ static_assert(
+ kNodeValues < (1 << (8 * sizeof(typename node_type::field_type))),
+ "target node size too large");
+
+ // Verify that key_compare returns an absl::{weak,strong}_ordering or bool.
+ using compare_result_type =
+ absl::result_of_t<key_compare(key_type, key_type)>;
+ static_assert(
+ std::is_same<compare_result_type, bool>::value ||
+ std::is_convertible<compare_result_type, absl::weak_ordering>::value,
+ "key comparison function must return absl::{weak,strong}_ordering or "
+ "bool.");
+
+ // Test the assumption made in setting kNodeValueSpace.
+ static_assert(node_type::MinimumOverhead() >= sizeof(void *) + 4,
+ "node space assumption incorrect");
+
+ return true;
}
template <typename P>
-btree<P>::btree(const self_type &x)
- : key_compare(x.key_comp()),
- root_(x.internal_allocator(), NULL) {
- assign(x);
+btree<P>::btree(const key_compare &comp, const allocator_type &alloc)
+ : root_(comp, alloc, EmptyNode()), rightmost_(EmptyNode()), size_(0) {}
+
+template <typename P>
+btree<P>::btree(const btree &x) : btree(x.key_comp(), x.allocator()) {
+ copy_or_move_values_in_order(&x);
}
-template <typename P> template <typename ValuePointer>
-std::pair<typename btree<P>::iterator, bool>
-btree<P>::insert_unique(const key_type &key, ValuePointer value) {
+template <typename P>
+template <typename... Args>
+auto btree<P>::insert_unique(const key_type &key, Args &&... args)
+ -> std::pair<iterator, bool> {
if (empty()) {
- *mutable_root() = new_leaf_root_node(1);
+ mutable_root() = rightmost_ = new_leaf_root_node(1);
}
- std::pair<iterator, int> res = internal_locate(key, iterator(root(), 0));
- iterator &iter = res.first;
- if (res.second == kExactMatch) {
- // The key already exists in the tree, do nothing.
- return std::make_pair(internal_last(iter), false);
- } else if (!res.second) {
+ auto res = internal_locate(key);
+ iterator &iter = res.value;
+
+ if (res.HasMatch()) {
+ if (res.IsEq()) {
+ // The key already exists in the tree, do nothing.
+ return {iter, false};
+ }
+ } else {
iterator last = internal_last(iter);
if (last.node && !compare_keys(key, last.key())) {
// The key already exists in the tree, do nothing.
- return std::make_pair(last, false);
+ return {last, false};
}
}
-
- return std::make_pair(internal_insert(iter, *value), true);
+ return {internal_emplace(iter, std::forward<Args>(args)...), true};
}
template <typename P>
-template <typename Value>
-inline typename btree<P>::iterator
-btree<P>::insert_unique(iterator position, Value&& v) {
+template <typename... Args>
+inline auto btree<P>::insert_hint_unique(iterator position, const key_type &key,
+ Args &&... args)
+ -> std::pair<iterator, bool> {
if (!empty()) {
- const key_type &key = params_type::key(v);
if (position == end() || compare_keys(key, position.key())) {
iterator prev = position;
if (position == begin() || compare_keys((--prev).key(), key)) {
// prev.key() < key < position.key()
- return internal_insert(position, v);
+ return {internal_emplace(position, std::forward<Args>(args)...), true};
}
} else if (compare_keys(position.key(), key)) {
- iterator next = position;
- ++next;
- if (next == end() || compare_keys(key, next.key())) {
- // position.key() < key < next.key()
- return internal_insert(next, v);
+ ++position;
+ if (position == end() || compare_keys(key, position.key())) {
+ // {original `position`}.key() < key < {current `position`}.key()
+ return {internal_emplace(position, std::forward<Args>(args)...), true};
}
} else {
// position.key() == key
- return position;
+ return {position, false};
}
}
- return insert_unique(std::forward<Value>(v)).first;
+ return insert_unique(key, std::forward<Args>(args)...);
}
-template <typename P> template <typename InputIterator>
-void btree<P>::insert_unique(InputIterator b, InputIterator e) {
+template <typename P>
+template <typename InputIterator>
+void btree<P>::insert_iterator_unique(InputIterator b, InputIterator e) {
for (; b != e; ++b) {
- insert_unique(end(), *b);
+ insert_hint_unique(end(), params_type::key(*b), *b);
}
}
-template <typename P> template <typename ValuePointer>
-typename btree<P>::iterator
-btree<P>::insert_multi(const key_type &key, ValuePointer value) {
+template <typename P>
+template <typename ValueType>
+auto btree<P>::insert_multi(const key_type &key, ValueType &&v) -> iterator {
if (empty()) {
- *mutable_root() = new_leaf_root_node(1);
+ mutable_root() = rightmost_ = new_leaf_root_node(1);
}
- iterator iter = internal_upper_bound(key, iterator(root(), 0));
- if (!iter.node) {
+ iterator iter = internal_upper_bound(key);
+ if (iter.node == nullptr) {
iter = end();
}
- return internal_insert(iter, *value);
+ return internal_emplace(iter, std::forward<ValueType>(v));
}
template <typename P>
-typename btree<P>::iterator
-btree<P>::insert_multi(iterator position, const value_type &v) {
+template <typename ValueType>
+auto btree<P>::insert_hint_multi(iterator position, ValueType &&v) -> iterator {
if (!empty()) {
const key_type &key = params_type::key(v);
if (position == end() || !compare_keys(position.key(), key)) {
iterator prev = position;
if (position == begin() || !compare_keys(key, (--prev).key())) {
// prev.key() <= key <= position.key()
- return internal_insert(position, v);
+ return internal_emplace(position, std::forward<ValueType>(v));
}
} else {
iterator next = position;
++next;
if (next == end() || !compare_keys(next.key(), key)) {
// position.key() < key <= next.key()
- return internal_insert(next, v);
+ return internal_emplace(next, std::forward<ValueType>(v));
}
}
}
- return insert_multi(v);
+ return insert_multi(std::forward<ValueType>(v));
}
-template <typename P> template <typename InputIterator>
-void btree<P>::insert_multi(InputIterator b, InputIterator e) {
+template <typename P>
+template <typename InputIterator>
+void btree<P>::insert_iterator_multi(InputIterator b, InputIterator e) {
for (; b != e; ++b) {
- insert_multi(end(), *b);
+ insert_hint_multi(end(), *b);
}
}
template <typename P>
-void btree<P>::assign(const self_type &x) {
- clear();
+auto btree<P>::operator=(const btree &x) -> btree & {
+ if (this != &x) {
+ clear();
- *mutable_key_comp() = x.key_comp();
- *mutable_internal_allocator() = x.internal_allocator();
+ *mutable_key_comp() = x.key_comp();
+ if (absl::allocator_traits<
+ allocator_type>::propagate_on_container_copy_assignment::value) {
+ *mutable_allocator() = x.allocator();
+ }
- // Assignment can avoid key comparisons because we know the order of the
- // values is the same order we'll store them in.
- for (const_iterator iter = x.begin(); iter != x.end(); ++iter) {
- if (empty()) {
- insert_multi(*iter);
+ copy_or_move_values_in_order(&x);
+ }
+ return *this;
+}
+
+template <typename P>
+auto btree<P>::operator=(btree &&x) noexcept -> btree & {
+ if (this != &x) {
+ clear();
+
+ using std::swap;
+ if (absl::allocator_traits<
+ allocator_type>::propagate_on_container_copy_assignment::value) {
+ // Note: `root_` also contains the allocator and the key comparator.
+ swap(root_, x.root_);
+ swap(rightmost_, x.rightmost_);
+ swap(size_, x.size_);
} else {
- // If the btree is not empty, we can just insert the new value at the end
- // of the tree!
- internal_insert(end(), *iter);
+ if (allocator() == x.allocator()) {
+ swap(mutable_root(), x.mutable_root());
+ swap(*mutable_key_comp(), *x.mutable_key_comp());
+ swap(rightmost_, x.rightmost_);
+ swap(size_, x.size_);
+ } else {
+ // We aren't allowed to propagate the allocator and the allocator is
+ // different so we can't take over its memory. We must move each element
+ // individually. We need both `x` and `this` to have `x`s key comparator
+ // while moving the values so we can't swap the key comparators.
+ *mutable_key_comp() = x.key_comp();
+ copy_or_move_values_in_order(&x);
+ }
}
}
+ return *this;
}
template <typename P>
-typename btree<P>::iterator btree<P>::erase(iterator iter) {
+auto btree<P>::erase(iterator iter) -> iterator {
bool internal_delete = false;
if (!iter.node->leaf()) {
- // Deletion of a value on an internal node. Swap the key with the largest
- // value of our left child. This is easy, we just decrement iter.
- iterator tmp_iter(iter--);
- ceph_assert(iter.node->leaf());
- ceph_assert(!compare_keys(tmp_iter.key(), iter.key()));
- iter.node->value_swap(iter.position, tmp_iter.node, tmp_iter.position);
+ // Deletion of a value on an internal node. First, move the largest value
+ // from our left child here, then delete that position (in remove_value()
+ // below). We can get to the largest value from our left child by
+ // decrementing iter.
+ iterator internal_iter(iter);
+ --iter;
+ assert(iter.node->leaf());
+ params_type::move(mutable_allocator(), iter.node->slot(iter.position),
+ internal_iter.node->slot(internal_iter.position));
internal_delete = true;
- --*mutable_size();
- } else if (!root()->leaf()) {
- --*mutable_size();
}
// Delete the key from the leaf.
- iter.node->remove_value(iter.position);
+ iter.node->remove_value(iter.position, mutable_allocator());
+ --size_;
// We want to return the next value after the one we just erased. If we
// erased from an internal node (internal_delete == true), then the next
// internal node and the value in the internal node may move to a leaf node
// (iter.node) when rebalancing is performed at the leaf level.
+ iterator res = rebalance_after_delete(iter);
+
+ // If we erased from an internal node, advance the iterator.
+ if (internal_delete) {
+ ++res;
+ }
+ return res;
+}
+
+template <typename P>
+auto btree<P>::rebalance_after_delete(iterator iter) -> iterator {
// Merge/rebalance as we walk back up the tree.
iterator res(iter);
+ bool first_iteration = true;
for (;;) {
if (iter.node == root()) {
try_shrink();
break;
}
bool merged = try_merge_or_rebalance(&iter);
- if (iter.node->leaf()) {
+ // On the first iteration, we should update `res` with `iter` because `res`
+ // may have been invalidated.
+ if (first_iteration) {
res = iter;
+ first_iteration = false;
}
if (!merged) {
break;
}
+ iter.position = iter.node->position();
iter.node = iter.node->parent();
}
res.position = res.node->count() - 1;
++res;
}
- // If we erased from an internal node, advance the iterator.
- if (internal_delete) {
- ++res;
- }
+
return res;
}
template <typename P>
-int btree<P>::erase(iterator begin, iterator end) {
- int count = distance(begin, end);
- for (int i = 0; i < count; i++) {
- begin = erase(begin);
+auto btree<P>::erase(iterator begin, iterator end)
+ -> std::pair<size_type, iterator> {
+ difference_type count = std::distance(begin, end);
+ assert(count >= 0);
+
+ if (count == 0) {
+ return {0, begin};
}
- return count;
+
+ if (count == size_) {
+ clear();
+ return {count, this->end()};
+ }
+
+ if (begin.node == end.node) {
+ erase_same_node(begin, end);
+ size_ -= count;
+ return {count, rebalance_after_delete(begin)};
+ }
+
+ const size_type target_size = size_ - count;
+ while (size_ > target_size) {
+ if (begin.node->leaf()) {
+ const size_type remaining_to_erase = size_ - target_size;
+ const size_type remaining_in_node = begin.node->count() - begin.position;
+ begin = erase_from_leaf_node(
+ begin, (std::min)(remaining_to_erase, remaining_in_node));
+ } else {
+ begin = erase(begin);
+ }
+ }
+ return {count, begin};
+}
+
+template <typename P>
+void btree<P>::erase_same_node(iterator begin, iterator end) {
+ assert(begin.node == end.node);
+ assert(end.position > begin.position);
+
+ node_type *node = begin.node;
+ size_type to_erase = end.position - begin.position;
+ if (!node->leaf()) {
+ // Delete all children between begin and end.
+ for (size_type i = 0; i < to_erase; ++i) {
+ internal_clear(node->child(begin.position + i + 1));
+ }
+ // Rotate children after end into new positions.
+ for (size_type i = begin.position + to_erase + 1; i <= node->count(); ++i) {
+ node->set_child(i - to_erase, node->child(i));
+ node->clear_child(i);
+ }
+ }
+ node->remove_values_ignore_children(begin.position, to_erase,
+ mutable_allocator());
+
+ // Do not need to update rightmost_, because
+ // * either end == this->end(), and therefore node == rightmost_, and still
+ // exists
+ // * or end != this->end(), and therefore rightmost_ hasn't been erased, since
+ // it wasn't covered in [begin, end)
+}
+
+template <typename P>
+auto btree<P>::erase_from_leaf_node(iterator begin, size_type to_erase)
+ -> iterator {
+ node_type *node = begin.node;
+ assert(node->leaf());
+ assert(node->count() > begin.position);
+ assert(begin.position + to_erase <= node->count());
+
+ node->remove_values_ignore_children(begin.position, to_erase,
+ mutable_allocator());
+
+ size_ -= to_erase;
+
+ return rebalance_after_delete(begin);
}
template <typename P>
-int btree<P>::erase_unique(const key_type &key) {
- iterator iter = internal_find_unique(key, iterator(root(), 0));
- if (!iter.node) {
+template <typename K>
+auto btree<P>::erase_unique(const K &key) -> size_type {
+ const iterator iter = internal_find(key);
+ if (iter.node == nullptr) {
// The key doesn't exist in the tree, return nothing done.
return 0;
}
}
template <typename P>
-int btree<P>::erase_multi(const key_type &key) {
- iterator begin = internal_lower_bound(key, iterator(root(), 0));
- if (!begin.node) {
+template <typename K>
+auto btree<P>::erase_multi(const K &key) -> size_type {
+ const iterator begin = internal_lower_bound(key);
+ if (begin.node == nullptr) {
// The key doesn't exist in the tree, return nothing done.
return 0;
}
// Delete all of the keys between begin and upper_bound(key).
- iterator end = internal_end(
- internal_upper_bound(key, iterator(root(), 0)));
- return erase(begin, end);
+ const iterator end = internal_end(internal_upper_bound(key));
+ return erase(begin, end).first;
}
template <typename P>
void btree<P>::clear() {
- if (root() != NULL) {
+ if (!empty()) {
internal_clear(root());
}
- *mutable_root() = NULL;
+ mutable_root() = EmptyNode();
+ rightmost_ = EmptyNode();
+ size_ = 0;
}
template <typename P>
-void btree<P>::swap(self_type &x) {
- std::swap(static_cast<key_compare&>(*this), static_cast<key_compare&>(x));
- std::swap(root_, x.root_);
+void btree<P>::swap(btree &x) {
+ using std::swap;
+ if (absl::allocator_traits<
+ allocator_type>::propagate_on_container_swap::value) {
+ // Note: `root_` also contains the allocator and the key comparator.
+ swap(root_, x.root_);
+ } else {
+ // It's undefined behavior if the allocators are unequal here.
+ assert(allocator() == x.allocator());
+ swap(mutable_root(), x.mutable_root());
+ swap(*mutable_key_comp(), *x.mutable_key_comp());
+ }
+ swap(rightmost_, x.rightmost_);
+ swap(size_, x.size_);
}
template <typename P>
void btree<P>::verify() const {
- if (root() != NULL) {
- ceph_assert(size() == internal_verify(root(), NULL, NULL));
- ceph_assert(leftmost() == (++const_iterator(root(), -1)).node);
- ceph_assert(rightmost() == (--const_iterator(root(), root()->count())).node);
- ceph_assert(leftmost()->leaf());
- ceph_assert(rightmost()->leaf());
- } else {
- ceph_assert(size() == 0);
- ceph_assert(leftmost() == NULL);
- ceph_assert(rightmost() == NULL);
- }
+ assert(root() != nullptr);
+ assert(leftmost() != nullptr);
+ assert(rightmost_ != nullptr);
+ assert(empty() || size() == internal_verify(root(), nullptr, nullptr));
+ assert(leftmost() == (++const_iterator(root(), -1)).node);
+ assert(rightmost_ == (--const_iterator(root(), root()->count())).node);
+ assert(leftmost()->leaf());
+ assert(rightmost_->leaf());
}
template <typename P>
void btree<P>::rebalance_or_split(iterator *iter) {
node_type *&node = iter->node;
int &insert_position = iter->position;
- ceph_assert(node->count() == node->max_count());
+ assert(node->count() == node->max_count());
+ assert(kNodeValues == node->max_count());
// First try to make room on the node by rebalancing.
node_type *parent = node->parent();
if (node->position() > 0) {
// Try rebalancing with our left sibling.
node_type *left = parent->child(node->position() - 1);
- if (left->count() < left->max_count()) {
+ assert(left->max_count() == kNodeValues);
+ if (left->count() < kNodeValues) {
// We bias rebalancing based on the position being inserted. If we're
// inserting at the end of the right node then we bias rebalancing to
// fill up the left node.
- int to_move = (left->max_count() - left->count()) /
- (1 + (insert_position < left->max_count()));
- to_move = std::max(1, to_move);
+ int to_move = (kNodeValues - left->count()) /
+ (1 + (insert_position < kNodeValues));
+ to_move = (std::max)(1, to_move);
if (((insert_position - to_move) >= 0) ||
- ((left->count() + to_move) < left->max_count())) {
- left->rebalance_right_to_left(node, to_move);
+ ((left->count() + to_move) < kNodeValues)) {
+ left->rebalance_right_to_left(to_move, node, mutable_allocator());
- ceph_assert(node->max_count() - node->count() == to_move);
+ assert(node->max_count() - node->count() == to_move);
insert_position = insert_position - to_move;
if (insert_position < 0) {
insert_position = insert_position + left->count() + 1;
node = left;
}
- ceph_assert(node->count() < node->max_count());
+ assert(node->count() < node->max_count());
return;
}
}
if (node->position() < parent->count()) {
// Try rebalancing with our right sibling.
node_type *right = parent->child(node->position() + 1);
- if (right->count() < right->max_count()) {
+ assert(right->max_count() == kNodeValues);
+ if (right->count() < kNodeValues) {
// We bias rebalancing based on the position being inserted. If we're
// inserting at the beginning of the left node then we bias rebalancing
// to fill up the right node.
- int to_move = (right->max_count() - right->count()) /
- (1 + (insert_position > 0));
- to_move = std::max(1, to_move);
+ int to_move =
+ (kNodeValues - right->count()) / (1 + (insert_position > 0));
+ to_move = (std::max)(1, to_move);
if ((insert_position <= (node->count() - to_move)) ||
- ((right->count() + to_move) < right->max_count())) {
- node->rebalance_left_to_right(right, to_move);
+ ((right->count() + to_move) < kNodeValues)) {
+ node->rebalance_left_to_right(to_move, right, mutable_allocator());
if (insert_position > node->count()) {
insert_position = insert_position - node->count() - 1;
node = right;
}
- ceph_assert(node->count() < node->max_count());
+ assert(node->count() < node->max_count());
return;
}
}
// Rebalancing failed, make sure there is room on the parent node for a new
// value.
- if (parent->count() == parent->max_count()) {
+ assert(parent->max_count() == kNodeValues);
+ if (parent->count() == kNodeValues) {
iterator parent_iter(node->parent(), node->position());
rebalance_or_split(&parent_iter);
}
} else {
// Rebalancing not possible because this is the root node.
- if (root()->leaf()) {
- // The root node is currently a leaf node: create a new root node and set
- // the current root node as the child of the new root.
- parent = new_internal_root_node();
- parent->set_child(0, root());
- *mutable_root() = parent;
- ceph_assert(*mutable_rightmost() == parent->child(0));
- } else {
- // The root node is an internal node. We do not want to create a new root
- // node because the root node is special and holds the size of the tree
- // and a pointer to the rightmost node. So we create a new internal node
- // and move all of the items on the current root into the new node.
- parent = new_internal_node(parent);
- parent->set_child(0, parent);
- parent->swap(root());
- node = parent;
- }
+ // Create a new root node and set the current root node as the child of the
+ // new root.
+ parent = new_internal_node(parent);
+ parent->init_child(0, root());
+ mutable_root() = parent;
+ // If the former root was a leaf node, then it's now the rightmost node.
+ assert(!parent->child(0)->leaf() || parent->child(0) == rightmost_);
}
// Split the node.
node_type *split_node;
if (node->leaf()) {
split_node = new_leaf_node(parent);
- node->split(split_node, insert_position);
- if (rightmost() == node) {
- *mutable_rightmost() = split_node;
- }
+ node->split(insert_position, split_node, mutable_allocator());
+ if (rightmost_ == node) rightmost_ = split_node;
} else {
split_node = new_internal_node(parent);
- node->split(split_node, insert_position);
+ node->split(insert_position, split_node, mutable_allocator());
}
if (insert_position > node->count()) {
template <typename P>
void btree<P>::merge_nodes(node_type *left, node_type *right) {
- left->merge(right);
+ left->merge(right, mutable_allocator());
if (right->leaf()) {
- if (rightmost() == right) {
- *mutable_rightmost() = left;
- }
+ if (rightmost_ == right) rightmost_ = left;
delete_leaf_node(right);
} else {
delete_internal_node(right);
if (iter->node->position() > 0) {
// Try merging with our left sibling.
node_type *left = parent->child(iter->node->position() - 1);
- if ((1 + left->count() + iter->node->count()) <= left->max_count()) {
+ assert(left->max_count() == kNodeValues);
+ if ((1 + left->count() + iter->node->count()) <= kNodeValues) {
iter->position += 1 + left->count();
merge_nodes(left, iter->node);
iter->node = left;
if (iter->node->position() < parent->count()) {
// Try merging with our right sibling.
node_type *right = parent->child(iter->node->position() + 1);
- if ((1 + iter->node->count() + right->count()) <= right->max_count()) {
+ assert(right->max_count() == kNodeValues);
+ if ((1 + iter->node->count() + right->count()) <= kNodeValues) {
merge_nodes(iter->node, right);
return true;
}
((iter->node->count() == 0) ||
(iter->position > 0))) {
int to_move = (right->count() - iter->node->count()) / 2;
- to_move = std::min(to_move, right->count() - 1);
- iter->node->rebalance_right_to_left(right, to_move);
+ to_move = (std::min)(to_move, right->count() - 1);
+ iter->node->rebalance_right_to_left(to_move, right, mutable_allocator());
return false;
}
}
((iter->node->count() == 0) ||
(iter->position < iter->node->count()))) {
int to_move = (left->count() - iter->node->count()) / 2;
- to_move = std::min(to_move, left->count() - 1);
- left->rebalance_left_to_right(iter->node, to_move);
+ to_move = (std::min)(to_move, left->count() - 1);
+ left->rebalance_left_to_right(to_move, iter->node, mutable_allocator());
iter->position += to_move;
return false;
}
}
// Deleted the last item on the root node, shrink the height of the tree.
if (root()->leaf()) {
- ceph_assert(size() == 0);
+ assert(size() == 0);
delete_leaf_node(root());
- *mutable_root() = NULL;
+ mutable_root() = EmptyNode();
+ rightmost_ = EmptyNode();
} else {
node_type *child = root()->child(0);
- if (child->leaf()) {
- // The child is a leaf node so simply make it the root node in the tree.
- child->make_root();
- delete_internal_root_node();
- *mutable_root() = child;
- } else {
- // The child is an internal node. We want to keep the existing root node
- // so we move all of the values from the child node into the existing
- // (empty) root node.
- child->swap(root());
- delete_internal_node(child);
- }
+ child->make_root();
+ delete_internal_node(root());
+ mutable_root() = child;
}
}
-template <typename P> template <typename IterType>
+template <typename P>
+template <typename IterType>
inline IterType btree<P>::internal_last(IterType iter) {
- while (iter.node && iter.position == iter.node->count()) {
+ assert(iter.node != nullptr);
+ while (iter.position == iter.node->count()) {
iter.position = iter.node->position();
iter.node = iter.node->parent();
if (iter.node->leaf()) {
- iter.node = NULL;
+ iter.node = nullptr;
+ break;
}
}
return iter;
}
template <typename P>
-template <typename Value>
-inline typename btree<P>::iterator
-btree<P>::internal_insert(iterator iter, Value&& v) {
+template <typename... Args>
+inline auto btree<P>::internal_emplace(iterator iter, Args &&... args)
+ -> iterator {
if (!iter.node->leaf()) {
// We can't insert on an internal node. Instead, we'll insert after the
// previous value which is guaranteed to be on a leaf node.
--iter;
++iter.position;
}
- if (iter.node->count() == iter.node->max_count()) {
+ const int max_count = iter.node->max_count();
+ if (iter.node->count() == max_count) {
// Make room in the leaf for the new item.
- if (iter.node->max_count() < kNodeValues) {
- // Insertion into the root where the root is smaller that the full node
+ if (max_count < kNodeValues) {
+ // Insertion into the root where the root is smaller than the full node
// size. Simply grow the size of the root node.
- ceph_assert(iter.node == root());
- iter.node = new_leaf_root_node(
- std::min<int>(kNodeValues, 2 * iter.node->max_count()));
- iter.node->swap(root());
+ assert(iter.node == root());
+ iter.node =
+ new_leaf_root_node((std::min<int>)(kNodeValues, 2 * max_count));
+ iter.node->swap(root(), mutable_allocator());
delete_leaf_node(root());
- *mutable_root() = iter.node;
+ mutable_root() = iter.node;
+ rightmost_ = iter.node;
} else {
rebalance_or_split(&iter);
- ++*mutable_size();
}
- } else if (!root()->leaf()) {
- ++*mutable_size();
}
- iter.node->insert_value(iter.position, std::forward<Value>(v));
+ iter.node->emplace_value(iter.position, mutable_allocator(),
+ std::forward<Args>(args)...);
+ ++size_;
return iter;
}
-template <typename P> template <typename IterType>
-inline std::pair<IterType, int> btree<P>::internal_locate(
- const key_type &key, IterType iter) const {
- return internal_locate_type::dispatch(key, *this, iter);
+template <typename P>
+template <typename K>
+inline auto btree<P>::internal_locate(const K &key) const
+ -> SearchResult<iterator, is_key_compare_to::value> {
+ return internal_locate_impl(key, is_key_compare_to());
}
-template <typename P> template <typename IterType>
-inline std::pair<IterType, int> btree<P>::internal_locate_plain_compare(
- const key_type &key, IterType iter) const {
+template <typename P>
+template <typename K>
+inline auto btree<P>::internal_locate_impl(
+ const K &key, std::false_type /* IsCompareTo */) const
+ -> SearchResult<iterator, false> {
+ iterator iter(const_cast<node_type *>(root()), 0);
for (;;) {
- iter.position = iter.node->lower_bound(key, key_comp());
+ iter.position = iter.node->lower_bound(key, key_comp()).value;
+ // NOTE: we don't need to walk all the way down the tree if the keys are
+ // equal, but determining equality would require doing an extra comparison
+ // on each node on the way down, and we will need to go all the way to the
+ // leaf node in the expected case.
if (iter.node->leaf()) {
break;
}
iter.node = iter.node->child(iter.position);
}
- return std::make_pair(iter, 0);
+ return {iter};
}
-template <typename P> template <typename IterType>
-inline std::pair<IterType, int> btree<P>::internal_locate_compare_to(
- const key_type &key, IterType iter) const {
+template <typename P>
+template <typename K>
+inline auto btree<P>::internal_locate_impl(
+ const K &key, std::true_type /* IsCompareTo */) const
+ -> SearchResult<iterator, true> {
+ iterator iter(const_cast<node_type *>(root()), 0);
for (;;) {
- int res = iter.node->lower_bound(key, key_comp());
- iter.position = res & kMatchMask;
- if (res & kExactMatch) {
- return std::make_pair(iter, static_cast<int>(kExactMatch));
+ SearchResult<int, true> res = iter.node->lower_bound(key, key_comp());
+ iter.position = res.value;
+ if (res.match == MatchKind::kEq) {
+ return {iter, MatchKind::kEq};
}
if (iter.node->leaf()) {
break;
}
iter.node = iter.node->child(iter.position);
}
- return std::make_pair(iter, -kExactMatch);
+ return {iter, MatchKind::kNe};
}
-template <typename P> template <typename IterType>
-IterType btree<P>::internal_lower_bound(
- const key_type &key, IterType iter) const {
- if (iter.node) {
- for (;;) {
- iter.position =
- iter.node->lower_bound(key, key_comp()) & kMatchMask;
- if (iter.node->leaf()) {
- break;
- }
- iter.node = iter.node->child(iter.position);
+template <typename P>
+template <typename K>
+auto btree<P>::internal_lower_bound(const K &key) const -> iterator {
+ iterator iter(const_cast<node_type *>(root()), 0);
+ for (;;) {
+ iter.position = iter.node->lower_bound(key, key_comp()).value;
+ if (iter.node->leaf()) {
+ break;
}
- iter = internal_last(iter);
+ iter.node = iter.node->child(iter.position);
}
- return iter;
+ return internal_last(iter);
}
-template <typename P> template <typename IterType>
-IterType btree<P>::internal_upper_bound(
- const key_type &key, IterType iter) const {
- if (iter.node) {
- for (;;) {
- iter.position = iter.node->upper_bound(key, key_comp());
- if (iter.node->leaf()) {
- break;
- }
- iter.node = iter.node->child(iter.position);
+template <typename P>
+template <typename K>
+auto btree<P>::internal_upper_bound(const K &key) const -> iterator {
+ iterator iter(const_cast<node_type *>(root()), 0);
+ for (;;) {
+ iter.position = iter.node->upper_bound(key, key_comp());
+ if (iter.node->leaf()) {
+ break;
}
- iter = internal_last(iter);
+ iter.node = iter.node->child(iter.position);
}
- return iter;
+ return internal_last(iter);
}
-template <typename P> template <typename IterType>
-IterType btree<P>::internal_find_unique(
- const key_type &key, IterType iter) const {
- if (iter.node) {
- std::pair<IterType, int> res = internal_locate(key, iter);
- if (res.second == kExactMatch) {
- return res.first;
- }
- if (!res.second) {
- iter = internal_last(res.first);
- if (iter.node && !compare_keys(key, iter.key())) {
- return iter;
- }
+template <typename P>
+template <typename K>
+auto btree<P>::internal_find(const K &key) const -> iterator {
+ auto res = internal_locate(key);
+ if (res.HasMatch()) {
+ if (res.IsEq()) {
+ return res.value;
}
- }
- return IterType(NULL, 0);
-}
-
-template <typename P> template <typename IterType>
-IterType btree<P>::internal_find_multi(
- const key_type &key, IterType iter) const {
- if (iter.node) {
- iter = internal_lower_bound(key, iter);
- if (iter.node) {
- iter = internal_last(iter);
- if (iter.node && !compare_keys(key, iter.key())) {
- return iter;
- }
+ } else {
+ const iterator iter = internal_last(res.value);
+ if (iter.node != nullptr && !compare_keys(key, iter.key())) {
+ return iter;
}
}
- return IterType(NULL, 0);
+ return {nullptr, 0};
}
template <typename P>
for (int i = 0; i <= node->count(); ++i) {
internal_clear(node->child(i));
}
- if (node == root()) {
- delete_internal_root_node();
- } else {
- delete_internal_node(node);
- }
+ delete_internal_node(node);
} else {
delete_leaf_node(node);
}
}
-template <typename P>
-void btree<P>::internal_dump(
- std::ostream &os, const node_type *node, int level) const {
- for (int i = 0; i < node->count(); ++i) {
- if (!node->leaf()) {
- internal_dump(os, node->child(i), level + 1);
- }
- for (int j = 0; j < level; ++j) {
- os << " ";
- }
- os << node->key(i) << " [" << level << "]\n";
- }
- if (!node->leaf()) {
- internal_dump(os, node->child(node->count()), level + 1);
- }
-}
-
template <typename P>
int btree<P>::internal_verify(
const node_type *node, const key_type *lo, const key_type *hi) const {
- ceph_assert(node->count() > 0);
- ceph_assert(node->count() <= node->max_count());
+ assert(node->count() > 0);
+ assert(node->count() <= node->max_count());
if (lo) {
- ceph_assert(!compare_keys(node->key(0), *lo));
+ assert(!compare_keys(node->key(0), *lo));
}
if (hi) {
- ceph_assert(!compare_keys(*hi, node->key(node->count() - 1)));
+ assert(!compare_keys(*hi, node->key(node->count() - 1)));
}
for (int i = 1; i < node->count(); ++i) {
- ceph_assert(!compare_keys(node->key(i), node->key(i - 1)));
+ assert(!compare_keys(node->key(i), node->key(i - 1)));
}
int count = node->count();
if (!node->leaf()) {
for (int i = 0; i <= node->count(); ++i) {
- ceph_assert(node->child(i) != NULL);
- ceph_assert(node->child(i)->parent() == node);
- ceph_assert(node->child(i)->position() == i);
+ assert(node->child(i) != nullptr);
+ assert(node->child(i)->parent() == node);
+ assert(node->child(i)->position() == i);
count += internal_verify(
node->child(i),
(i == 0) ? lo : &node->key(i - 1),
return count;
}
-} // namespace btree
+} // namespace container_internal
+ABSL_NAMESPACE_END
+} // namespace absl
-#endif // UTIL_BTREE_BTREE_H__
+#endif // ABSL_CONTAINER_INTERNAL_BTREE_H_
-// Copyright 2013 Google Inc. All Rights Reserved.
+// Copyright 2018 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
-// http://www.apache.org/licenses/LICENSE-2.0
+// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
-#ifndef UTIL_BTREE_BTREE_CONTAINER_H__
-#define UTIL_BTREE_BTREE_CONTAINER_H__
+#ifndef ABSL_CONTAINER_INTERNAL_BTREE_CONTAINER_H_
+#define ABSL_CONTAINER_INTERNAL_BTREE_CONTAINER_H_
-#include <iosfwd>
+#include <algorithm>
+#include <initializer_list>
+#include <iterator>
#include <utility>
-#include "btree.h"
+#include "absl/base/internal/throw_delegate.h"
+#include "absl/container/internal/btree.h" // IWYU pragma: export
+#include "absl/container/internal/common.h"
+#include "absl/meta/type_traits.h"
-namespace btree {
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace container_internal {
-// A common base class for btree_set, btree_map, btree_multiset and
+// A common base class for btree_set, btree_map, btree_multiset, and
// btree_multimap.
template <typename Tree>
class btree_container {
- typedef btree_container<Tree> self_type;
+ using params_type = typename Tree::params_type;
- public:
- typedef typename Tree::params_type params_type;
- typedef typename Tree::key_type key_type;
- typedef typename Tree::value_type value_type;
- typedef typename Tree::key_compare key_compare;
- typedef typename Tree::allocator_type allocator_type;
- typedef typename Tree::pointer pointer;
- typedef typename Tree::const_pointer const_pointer;
- typedef typename Tree::reference reference;
- typedef typename Tree::const_reference const_reference;
- typedef typename Tree::size_type size_type;
- typedef typename Tree::difference_type difference_type;
- typedef typename Tree::iterator iterator;
- typedef typename Tree::const_iterator const_iterator;
- typedef typename Tree::reverse_iterator reverse_iterator;
- typedef typename Tree::const_reverse_iterator const_reverse_iterator;
+ protected:
+ // Alias used for heterogeneous lookup functions.
+ // `key_arg<K>` evaluates to `K` when the functors are transparent and to
+ // `key_type` otherwise. It permits template argument deduction on `K` for the
+ // transparent case.
+ template <class K>
+ using key_arg =
+ typename KeyArg<IsTransparent<typename Tree::key_compare>::value>::
+ template type<K, typename Tree::key_type>;
public:
- // Default constructor.
- btree_container(const key_compare &comp, const allocator_type &alloc)
- : tree_(comp, alloc) {
- }
-
- // Copy constructor.
- btree_container(const self_type &x)
- : tree_(x.tree_) {
- }
+ using key_type = typename Tree::key_type;
+ using value_type = typename Tree::value_type;
+ using size_type = typename Tree::size_type;
+ using difference_type = typename Tree::difference_type;
+ using key_compare = typename Tree::key_compare;
+ using value_compare = typename Tree::value_compare;
+ using allocator_type = typename Tree::allocator_type;
+ using reference = typename Tree::reference;
+ using const_reference = typename Tree::const_reference;
+ using pointer = typename Tree::pointer;
+ using const_pointer = typename Tree::const_pointer;
+ using iterator = typename Tree::iterator;
+ using const_iterator = typename Tree::const_iterator;
+ using reverse_iterator = typename Tree::reverse_iterator;
+ using const_reverse_iterator = typename Tree::const_reverse_iterator;
+ using node_type = typename Tree::node_handle_type;
+
+ // Constructors/assignments.
+ btree_container() : tree_(key_compare(), allocator_type()) {}
+ explicit btree_container(const key_compare &comp,
+ const allocator_type &alloc = allocator_type())
+ : tree_(comp, alloc) {}
+ btree_container(const btree_container &x) = default;
+ btree_container(btree_container &&x) noexcept = default;
+ btree_container &operator=(const btree_container &x) = default;
+ btree_container &operator=(btree_container &&x) noexcept(
+ std::is_nothrow_move_assignable<Tree>::value) = default;
// Iterator routines.
iterator begin() { return tree_.begin(); }
const_iterator begin() const { return tree_.begin(); }
+ const_iterator cbegin() const { return tree_.begin(); }
iterator end() { return tree_.end(); }
const_iterator end() const { return tree_.end(); }
+ const_iterator cend() const { return tree_.end(); }
reverse_iterator rbegin() { return tree_.rbegin(); }
const_reverse_iterator rbegin() const { return tree_.rbegin(); }
+ const_reverse_iterator crbegin() const { return tree_.rbegin(); }
reverse_iterator rend() { return tree_.rend(); }
const_reverse_iterator rend() const { return tree_.rend(); }
+ const_reverse_iterator crend() const { return tree_.rend(); }
// Lookup routines.
- iterator lower_bound(const key_type &key) {
+ template <typename K = key_type>
+ iterator find(const key_arg<K> &key) {
+ return tree_.find(key);
+ }
+ template <typename K = key_type>
+ const_iterator find(const key_arg<K> &key) const {
+ return tree_.find(key);
+ }
+ template <typename K = key_type>
+ bool contains(const key_arg<K> &key) const {
+ return find(key) != end();
+ }
+ template <typename K = key_type>
+ iterator lower_bound(const key_arg<K> &key) {
return tree_.lower_bound(key);
}
- const_iterator lower_bound(const key_type &key) const {
+ template <typename K = key_type>
+ const_iterator lower_bound(const key_arg<K> &key) const {
return tree_.lower_bound(key);
}
- iterator upper_bound(const key_type &key) {
+ template <typename K = key_type>
+ iterator upper_bound(const key_arg<K> &key) {
return tree_.upper_bound(key);
}
- const_iterator upper_bound(const key_type &key) const {
+ template <typename K = key_type>
+ const_iterator upper_bound(const key_arg<K> &key) const {
return tree_.upper_bound(key);
}
- std::pair<iterator,iterator> equal_range(const key_type &key) {
+ template <typename K = key_type>
+ std::pair<iterator, iterator> equal_range(const key_arg<K> &key) {
return tree_.equal_range(key);
}
- std::pair<const_iterator,const_iterator> equal_range(const key_type &key) const {
+ template <typename K = key_type>
+ std::pair<const_iterator, const_iterator> equal_range(
+ const key_arg<K> &key) const {
return tree_.equal_range(key);
}
- // Utility routines.
- void clear() {
- tree_.clear();
- }
- void swap(self_type &x) {
- tree_.swap(x.tree_);
+ // Deletion routines. Note that there is also a deletion routine that is
+ // specific to btree_set_container/btree_multiset_container.
+
+ // Erase the specified iterator from the btree. The iterator must be valid
+ // (i.e. not equal to end()). Return an iterator pointing to the node after
+ // the one that was erased (or end() if none exists).
+ iterator erase(const_iterator iter) { return tree_.erase(iterator(iter)); }
+ iterator erase(iterator iter) { return tree_.erase(iter); }
+ iterator erase(const_iterator first, const_iterator last) {
+ return tree_.erase(iterator(first), iterator(last)).second;
}
- void dump(std::ostream &os) const {
- tree_.dump(os);
+
+ // Extract routines.
+ node_type extract(iterator position) {
+ // Use Move instead of Transfer, because the rebalancing code expects to
+ // have a valid object to scribble metadata bits on top of.
+ auto node = CommonAccess::Move<node_type>(get_allocator(), position.slot());
+ erase(position);
+ return node;
}
- void verify() const {
- tree_.verify();
+ node_type extract(const_iterator position) {
+ return extract(iterator(position));
}
+ public:
+ // Utility routines.
+ void clear() { tree_.clear(); }
+ void swap(btree_container &x) { tree_.swap(x.tree_); }
+ void verify() const { tree_.verify(); }
+
// Size routines.
size_type size() const { return tree_.size(); }
size_type max_size() const { return tree_.max_size(); }
bool empty() const { return tree_.empty(); }
- size_type height() const { return tree_.height(); }
- size_type internal_nodes() const { return tree_.internal_nodes(); }
- size_type leaf_nodes() const { return tree_.leaf_nodes(); }
- size_type nodes() const { return tree_.nodes(); }
- size_type bytes_used() const { return tree_.bytes_used(); }
- static double average_bytes_per_value() {
- return Tree::average_bytes_per_value();
- }
- double fullness() const { return tree_.fullness(); }
- double overhead() const { return tree_.overhead(); }
-
- bool operator==(const self_type& x) const {
- if (size() != x.size()) {
- return false;
- }
- for (const_iterator i = begin(), xi = x.begin(); i != end(); ++i, ++xi) {
- if (*i != *xi) {
- return false;
- }
- }
- return true;
+
+ friend bool operator==(const btree_container &x, const btree_container &y) {
+ if (x.size() != y.size()) return false;
+ return std::equal(x.begin(), x.end(), y.begin());
}
- bool operator!=(const self_type& other) const {
- return !operator==(other);
+ friend bool operator!=(const btree_container &x, const btree_container &y) {
+ return !(x == y);
}
+ friend bool operator<(const btree_container &x, const btree_container &y) {
+ return std::lexicographical_compare(x.begin(), x.end(), y.begin(), y.end());
+ }
+
+ friend bool operator>(const btree_container &x, const btree_container &y) {
+ return y < x;
+ }
+
+ friend bool operator<=(const btree_container &x, const btree_container &y) {
+ return !(y < x);
+ }
+
+ friend bool operator>=(const btree_container &x, const btree_container &y) {
+ return !(x < y);
+ }
+
+ // The allocator used by the btree.
+ allocator_type get_allocator() const { return tree_.get_allocator(); }
+
+ // The key comparator used by the btree.
+ key_compare key_comp() const { return tree_.key_comp(); }
+ value_compare value_comp() const { return tree_.value_comp(); }
+
+ // Support absl::Hash.
+ template <typename State>
+ friend State AbslHashValue(State h, const btree_container &b) {
+ for (const auto &v : b) {
+ h = State::combine(std::move(h), v);
+ }
+ return State::combine(std::move(h), b.size());
+ }
protected:
Tree tree_;
};
-template <typename T>
-inline std::ostream& operator<<(std::ostream &os, const btree_container<T> &b) {
- b.dump(os);
- return os;
-}
-
-// A common base class for btree_set and safe_btree_set.
+// A common base class for btree_set and btree_map.
template <typename Tree>
-class btree_unique_container : public btree_container<Tree> {
- typedef btree_unique_container<Tree> self_type;
- typedef btree_container<Tree> super_type;
+class btree_set_container : public btree_container<Tree> {
+ using super_type = btree_container<Tree>;
+ using params_type = typename Tree::params_type;
+ using init_type = typename params_type::init_type;
+ using is_key_compare_to = typename params_type::is_key_compare_to;
+ friend class BtreeNodePeer;
- public:
- typedef typename Tree::key_type key_type;
- typedef typename Tree::value_type value_type;
- typedef typename Tree::size_type size_type;
- typedef typename Tree::key_compare key_compare;
- typedef typename Tree::allocator_type allocator_type;
- typedef typename Tree::iterator iterator;
- typedef typename Tree::const_iterator const_iterator;
+ protected:
+ template <class K>
+ using key_arg = typename super_type::template key_arg<K>;
public:
- // Default constructor.
- btree_unique_container(const key_compare &comp = key_compare(),
- const allocator_type &alloc = allocator_type())
- : super_type(comp, alloc) {
- }
-
- // Copy constructor.
- btree_unique_container(const self_type &x)
- : super_type(x) {
- }
+ using key_type = typename Tree::key_type;
+ using value_type = typename Tree::value_type;
+ using size_type = typename Tree::size_type;
+ using key_compare = typename Tree::key_compare;
+ using allocator_type = typename Tree::allocator_type;
+ using iterator = typename Tree::iterator;
+ using const_iterator = typename Tree::const_iterator;
+ using node_type = typename super_type::node_type;
+ using insert_return_type = InsertReturnType<iterator, node_type>;
+
+ // Inherit constructors.
+ using super_type::super_type;
+ btree_set_container() {}
// Range constructor.
template <class InputIterator>
- btree_unique_container(InputIterator b, InputIterator e,
- const key_compare &comp = key_compare(),
- const allocator_type &alloc = allocator_type())
+ btree_set_container(InputIterator b, InputIterator e,
+ const key_compare &comp = key_compare(),
+ const allocator_type &alloc = allocator_type())
: super_type(comp, alloc) {
insert(b, e);
}
+ // Initializer list constructor.
+ btree_set_container(std::initializer_list<init_type> init,
+ const key_compare &comp = key_compare(),
+ const allocator_type &alloc = allocator_type())
+ : btree_set_container(init.begin(), init.end(), comp, alloc) {}
+
// Lookup routines.
- iterator find(const key_type &key) {
- return this->tree_.find_unique(key);
- }
- const_iterator find(const key_type &key) const {
- return this->tree_.find_unique(key);
- }
- size_type count(const key_type &key) const {
+ template <typename K = key_type>
+ size_type count(const key_arg<K> &key) const {
return this->tree_.count_unique(key);
}
// Insertion routines.
- std::pair<iterator,bool> insert(const value_type &x) {
- return this->tree_.insert_unique(x);
- }
- iterator insert(iterator position, const value_type &x) {
- return this->tree_.insert_unique(position, x);
- }
- template<class... Args>
- iterator emplace_hint(iterator hint, Args&&... args) {
- return this->tree_.insert_unique(hint,
- value_type(std::forward<Args>(args)...));
+ std::pair<iterator, bool> insert(const value_type &x) {
+ return this->tree_.insert_unique(params_type::key(x), x);
+ }
+ std::pair<iterator, bool> insert(value_type &&x) {
+ return this->tree_.insert_unique(params_type::key(x), std::move(x));
+ }
+ template <typename... Args>
+ std::pair<iterator, bool> emplace(Args &&... args) {
+ init_type v(std::forward<Args>(args)...);
+ return this->tree_.insert_unique(params_type::key(v), std::move(v));
+ }
+ iterator insert(const_iterator position, const value_type &x) {
+ return this->tree_
+ .insert_hint_unique(iterator(position), params_type::key(x), x)
+ .first;
+ }
+ iterator insert(const_iterator position, value_type &&x) {
+ return this->tree_
+ .insert_hint_unique(iterator(position), params_type::key(x),
+ std::move(x))
+ .first;
+ }
+ template <typename... Args>
+ iterator emplace_hint(const_iterator position, Args &&... args) {
+ init_type v(std::forward<Args>(args)...);
+ return this->tree_
+ .insert_hint_unique(iterator(position), params_type::key(v),
+ std::move(v))
+ .first;
}
template <typename InputIterator>
void insert(InputIterator b, InputIterator e) {
- this->tree_.insert_unique(b, e);
+ this->tree_.insert_iterator_unique(b, e);
+ }
+ void insert(std::initializer_list<init_type> init) {
+ this->tree_.insert_iterator_unique(init.begin(), init.end());
+ }
+ insert_return_type insert(node_type &&node) {
+ if (!node) return {this->end(), false, node_type()};
+ std::pair<iterator, bool> res =
+ this->tree_.insert_unique(params_type::key(CommonAccess::GetSlot(node)),
+ CommonAccess::GetSlot(node));
+ if (res.second) {
+ CommonAccess::Destroy(&node);
+ return {res.first, true, node_type()};
+ } else {
+ return {res.first, false, std::move(node)};
+ }
+ }
+ iterator insert(const_iterator hint, node_type &&node) {
+ if (!node) return this->end();
+ std::pair<iterator, bool> res = this->tree_.insert_hint_unique(
+ iterator(hint), params_type::key(CommonAccess::GetSlot(node)),
+ CommonAccess::GetSlot(node));
+ if (res.second) CommonAccess::Destroy(&node);
+ return res.first;
}
// Deletion routines.
- int erase(const key_type &key) {
+ template <typename K = key_type>
+ size_type erase(const key_arg<K> &key) {
return this->tree_.erase_unique(key);
}
- // Erase the specified iterator from the btree. The iterator must be valid
- // (i.e. not equal to end()). Return an iterator pointing to the node after
- // the one that was erased (or end() if none exists).
- iterator erase(const iterator &iter) {
- return this->tree_.erase(iter);
+ using super_type::erase;
+
+ // Node extraction routines.
+ template <typename K = key_type>
+ node_type extract(const key_arg<K> &key) {
+ auto it = this->find(key);
+ return it == this->end() ? node_type() : extract(it);
+ }
+ using super_type::extract;
+
+ // Merge routines.
+ // Moves elements from `src` into `this`. If the element already exists in
+ // `this`, it is left unmodified in `src`.
+ template <
+ typename T,
+ typename absl::enable_if_t<
+ absl::conjunction<
+ std::is_same<value_type, typename T::value_type>,
+ std::is_same<allocator_type, typename T::allocator_type>,
+ std::is_same<typename params_type::is_map_container,
+ typename T::params_type::is_map_container>>::value,
+ int> = 0>
+ void merge(btree_container<T> &src) { // NOLINT
+ for (auto src_it = src.begin(); src_it != src.end();) {
+ if (insert(std::move(*src_it)).second) {
+ src_it = src.erase(src_it);
+ } else {
+ ++src_it;
+ }
+ }
}
- void erase(const iterator &first, const iterator &last) {
- this->tree_.erase(first, last);
+
+ template <
+ typename T,
+ typename absl::enable_if_t<
+ absl::conjunction<
+ std::is_same<value_type, typename T::value_type>,
+ std::is_same<allocator_type, typename T::allocator_type>,
+ std::is_same<typename params_type::is_map_container,
+ typename T::params_type::is_map_container>>::value,
+ int> = 0>
+ void merge(btree_container<T> &&src) {
+ merge(src);
}
};
-// A common base class for btree_map and safe_btree_map.
+// Base class for btree_map.
template <typename Tree>
-class btree_map_container : public btree_unique_container<Tree> {
- typedef btree_map_container<Tree> self_type;
- typedef btree_unique_container<Tree> super_type;
+class btree_map_container : public btree_set_container<Tree> {
+ using super_type = btree_set_container<Tree>;
+ using params_type = typename Tree::params_type;
- public:
- typedef typename Tree::key_type key_type;
- typedef typename Tree::data_type data_type;
- typedef typename Tree::value_type value_type;
- typedef typename Tree::mapped_type mapped_type;
- typedef typename Tree::key_compare key_compare;
- typedef typename Tree::allocator_type allocator_type;
-
- private:
- // A pointer-like object which only generates its value when
- // dereferenced. Used by operator[] to avoid constructing an empty data_type
- // if the key already exists in the map.
- struct generate_value {
- generate_value(const key_type &k)
- : key(k) {
- }
- value_type operator*() const {
- return std::make_pair(key, data_type());
- }
- const key_type &key;
- };
+ protected:
+ template <class K>
+ using key_arg = typename super_type::template key_arg<K>;
public:
- // Default constructor.
- btree_map_container(const key_compare &comp = key_compare(),
- const allocator_type &alloc = allocator_type())
- : super_type(comp, alloc) {
- }
-
- // Copy constructor.
- btree_map_container(const self_type &x)
- : super_type(x) {
- }
-
- // Range constructor.
- template <class InputIterator>
- btree_map_container(InputIterator b, InputIterator e,
- const key_compare &comp = key_compare(),
- const allocator_type &alloc = allocator_type())
- : super_type(b, e, comp, alloc) {
- }
+ using key_type = typename Tree::key_type;
+ using mapped_type = typename params_type::mapped_type;
+ using value_type = typename Tree::value_type;
+ using key_compare = typename Tree::key_compare;
+ using allocator_type = typename Tree::allocator_type;
+ using iterator = typename Tree::iterator;
+ using const_iterator = typename Tree::const_iterator;
+
+ // Inherit constructors.
+ using super_type::super_type;
+ btree_map_container() {}
// Insertion routines.
- data_type& operator[](const key_type &key) {
- return this->tree_.insert_unique(key, generate_value(key)).first->second;
+ template <typename... Args>
+ std::pair<iterator, bool> try_emplace(const key_type &k, Args &&... args) {
+ return this->tree_.insert_unique(
+ k, std::piecewise_construct, std::forward_as_tuple(k),
+ std::forward_as_tuple(std::forward<Args>(args)...));
+ }
+ template <typename... Args>
+ std::pair<iterator, bool> try_emplace(key_type &&k, Args &&... args) {
+ // Note: `key_ref` exists to avoid a ClangTidy warning about moving from `k`
+ // and then using `k` unsequenced. This is safe because the move is into a
+ // forwarding reference and insert_unique guarantees that `key` is never
+ // referenced after consuming `args`.
+ const key_type& key_ref = k;
+ return this->tree_.insert_unique(
+ key_ref, std::piecewise_construct, std::forward_as_tuple(std::move(k)),
+ std::forward_as_tuple(std::forward<Args>(args)...));
+ }
+ template <typename... Args>
+ iterator try_emplace(const_iterator hint, const key_type &k,
+ Args &&... args) {
+ return this->tree_
+ .insert_hint_unique(iterator(hint), k, std::piecewise_construct,
+ std::forward_as_tuple(k),
+ std::forward_as_tuple(std::forward<Args>(args)...))
+ .first;
+ }
+ template <typename... Args>
+ iterator try_emplace(const_iterator hint, key_type &&k, Args &&... args) {
+ // Note: `key_ref` exists to avoid a ClangTidy warning about moving from `k`
+ // and then using `k` unsequenced. This is safe because the move is into a
+ // forwarding reference and insert_hint_unique guarantees that `key` is
+ // never referenced after consuming `args`.
+ const key_type& key_ref = k;
+ return this->tree_
+ .insert_hint_unique(iterator(hint), key_ref, std::piecewise_construct,
+ std::forward_as_tuple(std::move(k)),
+ std::forward_as_tuple(std::forward<Args>(args)...))
+ .first;
+ }
+ mapped_type &operator[](const key_type &k) {
+ return try_emplace(k).first->second;
+ }
+ mapped_type &operator[](key_type &&k) {
+ return try_emplace(std::move(k)).first->second;
+ }
+
+ template <typename K = key_type>
+ mapped_type &at(const key_arg<K> &key) {
+ auto it = this->find(key);
+ if (it == this->end())
+ base_internal::ThrowStdOutOfRange("absl::btree_map::at");
+ return it->second;
+ }
+ template <typename K = key_type>
+ const mapped_type &at(const key_arg<K> &key) const {
+ auto it = this->find(key);
+ if (it == this->end())
+ base_internal::ThrowStdOutOfRange("absl::btree_map::at");
+ return it->second;
}
};
// A common base class for btree_multiset and btree_multimap.
template <typename Tree>
-class btree_multi_container : public btree_container<Tree> {
- typedef btree_multi_container<Tree> self_type;
- typedef btree_container<Tree> super_type;
+class btree_multiset_container : public btree_container<Tree> {
+ using super_type = btree_container<Tree>;
+ using params_type = typename Tree::params_type;
+ using init_type = typename params_type::init_type;
+ using is_key_compare_to = typename params_type::is_key_compare_to;
- public:
- typedef typename Tree::key_type key_type;
- typedef typename Tree::value_type value_type;
- typedef typename Tree::size_type size_type;
- typedef typename Tree::key_compare key_compare;
- typedef typename Tree::allocator_type allocator_type;
- typedef typename Tree::iterator iterator;
- typedef typename Tree::const_iterator const_iterator;
+ template <class K>
+ using key_arg = typename super_type::template key_arg<K>;
public:
- // Default constructor.
- btree_multi_container(const key_compare &comp = key_compare(),
- const allocator_type &alloc = allocator_type())
- : super_type(comp, alloc) {
- }
-
- // Copy constructor.
- btree_multi_container(const self_type &x)
- : super_type(x) {
- }
+ using key_type = typename Tree::key_type;
+ using value_type = typename Tree::value_type;
+ using size_type = typename Tree::size_type;
+ using key_compare = typename Tree::key_compare;
+ using allocator_type = typename Tree::allocator_type;
+ using iterator = typename Tree::iterator;
+ using const_iterator = typename Tree::const_iterator;
+ using node_type = typename super_type::node_type;
+
+ // Inherit constructors.
+ using super_type::super_type;
+ btree_multiset_container() {}
// Range constructor.
template <class InputIterator>
- btree_multi_container(InputIterator b, InputIterator e,
- const key_compare &comp = key_compare(),
- const allocator_type &alloc = allocator_type())
+ btree_multiset_container(InputIterator b, InputIterator e,
+ const key_compare &comp = key_compare(),
+ const allocator_type &alloc = allocator_type())
: super_type(comp, alloc) {
insert(b, e);
}
+ // Initializer list constructor.
+ btree_multiset_container(std::initializer_list<init_type> init,
+ const key_compare &comp = key_compare(),
+ const allocator_type &alloc = allocator_type())
+ : btree_multiset_container(init.begin(), init.end(), comp, alloc) {}
+
// Lookup routines.
- iterator find(const key_type &key) {
- return this->tree_.find_multi(key);
- }
- const_iterator find(const key_type &key) const {
- return this->tree_.find_multi(key);
- }
- size_type count(const key_type &key) const {
+ template <typename K = key_type>
+ size_type count(const key_arg<K> &key) const {
return this->tree_.count_multi(key);
}
// Insertion routines.
- iterator insert(const value_type &x) {
- return this->tree_.insert_multi(x);
+ iterator insert(const value_type &x) { return this->tree_.insert_multi(x); }
+ iterator insert(value_type &&x) {
+ return this->tree_.insert_multi(std::move(x));
+ }
+ iterator insert(const_iterator position, const value_type &x) {
+ return this->tree_.insert_hint_multi(iterator(position), x);
}
- iterator insert(iterator position, const value_type &x) {
- return this->tree_.insert_multi(position, x);
+ iterator insert(const_iterator position, value_type &&x) {
+ return this->tree_.insert_hint_multi(iterator(position), std::move(x));
}
template <typename InputIterator>
void insert(InputIterator b, InputIterator e) {
- this->tree_.insert_multi(b, e);
+ this->tree_.insert_iterator_multi(b, e);
+ }
+ void insert(std::initializer_list<init_type> init) {
+ this->tree_.insert_iterator_multi(init.begin(), init.end());
+ }
+ template <typename... Args>
+ iterator emplace(Args &&... args) {
+ return this->tree_.insert_multi(init_type(std::forward<Args>(args)...));
+ }
+ template <typename... Args>
+ iterator emplace_hint(const_iterator position, Args &&... args) {
+ return this->tree_.insert_hint_multi(
+ iterator(position), init_type(std::forward<Args>(args)...));
+ }
+ iterator insert(node_type &&node) {
+ if (!node) return this->end();
+ iterator res =
+ this->tree_.insert_multi(params_type::key(CommonAccess::GetSlot(node)),
+ CommonAccess::GetSlot(node));
+ CommonAccess::Destroy(&node);
+ return res;
+ }
+ iterator insert(const_iterator hint, node_type &&node) {
+ if (!node) return this->end();
+ iterator res = this->tree_.insert_hint_multi(
+ iterator(hint),
+ std::move(params_type::element(CommonAccess::GetSlot(node))));
+ CommonAccess::Destroy(&node);
+ return res;
}
// Deletion routines.
- int erase(const key_type &key) {
+ template <typename K = key_type>
+ size_type erase(const key_arg<K> &key) {
return this->tree_.erase_multi(key);
}
- // Erase the specified iterator from the btree. The iterator must be valid
- // (i.e. not equal to end()). Return an iterator pointing to the node after
- // the one that was erased (or end() if none exists).
- iterator erase(const iterator &iter) {
- return this->tree_.erase(iter);
- }
- void erase(const iterator &first, const iterator &last) {
- this->tree_.erase(first, last);
+ using super_type::erase;
+
+ // Node extraction routines.
+ template <typename K = key_type>
+ node_type extract(const key_arg<K> &key) {
+ auto it = this->find(key);
+ return it == this->end() ? node_type() : extract(it);
+ }
+ using super_type::extract;
+
+ // Merge routines.
+ // Moves all elements from `src` into `this`.
+ template <
+ typename T,
+ typename absl::enable_if_t<
+ absl::conjunction<
+ std::is_same<value_type, typename T::value_type>,
+ std::is_same<allocator_type, typename T::allocator_type>,
+ std::is_same<typename params_type::is_map_container,
+ typename T::params_type::is_map_container>>::value,
+ int> = 0>
+ void merge(btree_container<T> &src) { // NOLINT
+ insert(std::make_move_iterator(src.begin()),
+ std::make_move_iterator(src.end()));
+ src.clear();
+ }
+
+ template <
+ typename T,
+ typename absl::enable_if_t<
+ absl::conjunction<
+ std::is_same<value_type, typename T::value_type>,
+ std::is_same<allocator_type, typename T::allocator_type>,
+ std::is_same<typename params_type::is_map_container,
+ typename T::params_type::is_map_container>>::value,
+ int> = 0>
+ void merge(btree_container<T> &&src) {
+ merge(src);
}
};
-} // namespace btree
+// A base class for btree_multimap.
+template <typename Tree>
+class btree_multimap_container : public btree_multiset_container<Tree> {
+ using super_type = btree_multiset_container<Tree>;
+ using params_type = typename Tree::params_type;
+
+ public:
+ using mapped_type = typename params_type::mapped_type;
+
+ // Inherit constructors.
+ using super_type::super_type;
+ btree_multimap_container() {}
+};
+
+} // namespace container_internal
+ABSL_NAMESPACE_END
+} // namespace absl
-#endif // UTIL_BTREE_BTREE_CONTAINER_H__
+#endif // ABSL_CONTAINER_INTERNAL_BTREE_CONTAINER_H_
-// Copyright 2013 Google Inc. All Rights Reserved.
+// Copyright 2018 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
-// http://www.apache.org/licenses/LICENSE-2.0
+// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
//
-// A btree_map<> implements the STL unique sorted associative container
-// interface and the pair associative container interface (a.k.a map<>) using a
-// btree. A btree_multimap<> implements the STL multiple sorted associative
-// container interface and the pair associtive container interface (a.k.a
-// multimap<>) using a btree. See btree.h for details of the btree
-// implementation and caveats.
-
-#ifndef UTIL_BTREE_BTREE_MAP_H__
-#define UTIL_BTREE_BTREE_MAP_H__
-
-#include <algorithm>
-#include <functional>
-#include <memory>
-#include <string>
-#include <utility>
-
-#include "btree.h"
-#include "btree_container.h"
-
-namespace btree {
-
-// The btree_map class is needed mainly for its constructors.
-template <typename Key, typename Value,
- typename Compare = std::less<Key>,
- typename Alloc = std::allocator<std::pair<const Key, Value> >,
- int TargetNodeSize = 256>
-class btree_map : public btree_map_container<
- btree<btree_map_params<Key, Value, Compare, Alloc, TargetNodeSize> > > {
-
- typedef btree_map<Key, Value, Compare, Alloc, TargetNodeSize> self_type;
- typedef btree_map_params<
- Key, Value, Compare, Alloc, TargetNodeSize> params_type;
- typedef btree<params_type> btree_type;
- typedef btree_map_container<btree_type> super_type;
+// -----------------------------------------------------------------------------
+// File: btree_map.h
+// -----------------------------------------------------------------------------
+//
+// This header file defines B-tree maps: sorted associative containers mapping
+// keys to values.
+//
+// * `absl::btree_map<>`
+// * `absl::btree_multimap<>`
+//
+// These B-tree types are similar to the corresponding types in the STL
+// (`std::map` and `std::multimap`) and generally conform to the STL interfaces
+// of those types. However, because they are implemented using B-trees, they
+// are more efficient in most situations.
+//
+// Unlike `std::map` and `std::multimap`, which are commonly implemented using
+// red-black tree nodes, B-tree maps use more generic B-tree nodes able to hold
+// multiple values per node. Holding multiple values per node often makes
+// B-tree maps perform better than their `std::map` counterparts, because
+// multiple entries can be checked within the same cache hit.
+//
+// However, these types should not be considered drop-in replacements for
+// `std::map` and `std::multimap` as there are some API differences, which are
+// noted in this header file.
+//
+// Importantly, insertions and deletions may invalidate outstanding iterators,
+// pointers, and references to elements. Such invalidations are typically only
+// an issue if insertion and deletion operations are interleaved with the use of
+// more than one iterator, pointer, or reference simultaneously. For this
+// reason, `insert()` and `erase()` return a valid iterator at the current
+// position.
- public:
- typedef typename btree_type::key_compare key_compare;
- typedef typename btree_type::allocator_type allocator_type;
+#ifndef ABSL_CONTAINER_BTREE_MAP_H_
+#define ABSL_CONTAINER_BTREE_MAP_H_
+
+#include "absl/container/internal/btree.h" // IWYU pragma: export
+#include "absl/container/internal/btree_container.h" // IWYU pragma: export
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+
+// absl::btree_map<>
+//
+// An `absl::btree_map<K, V>` is an ordered associative container of
+// unique keys and associated values designed to be a more efficient replacement
+// for `std::map` (in most cases).
+//
+// Keys are sorted using an (optional) comparison function, which defaults to
+// `std::less<K>`.
+//
+// An `absl::btree_map<K, V>` uses a default allocator of
+// `std::allocator<std::pair<const K, V>>` to allocate (and deallocate)
+// nodes, and construct and destruct values within those nodes. You may
+// instead specify a custom allocator `A` (which in turn requires specifying a
+// custom comparator `C`) as in `absl::btree_map<K, V, C, A>`.
+//
+template <typename Key, typename Value, typename Compare = std::less<Key>,
+ typename Alloc = std::allocator<std::pair<const Key, Value>>>
+class btree_map
+ : public container_internal::btree_map_container<
+ container_internal::btree<container_internal::map_params<
+ Key, Value, Compare, Alloc, /*TargetNodeSize=*/256,
+ /*Multi=*/false>>> {
+ using Base = typename btree_map::btree_map_container;
public:
- // Default constructor.
- btree_map(const key_compare &comp = key_compare(),
- const allocator_type &alloc = allocator_type())
- : super_type(comp, alloc) {
- }
+ // Constructors and Assignment Operators
+ //
+ // A `btree_map` supports the same overload set as `std::map`
+ // for construction and assignment:
+ //
+ // * Default constructor
+ //
+ // absl::btree_map<int, std::string> map1;
+ //
+ // * Initializer List constructor
+ //
+ // absl::btree_map<int, std::string> map2 =
+ // {{1, "huey"}, {2, "dewey"}, {3, "louie"},};
+ //
+ // * Copy constructor
+ //
+ // absl::btree_map<int, std::string> map3(map2);
+ //
+ // * Copy assignment operator
+ //
+ // absl::btree_map<int, std::string> map4;
+ // map4 = map3;
+ //
+ // * Move constructor
+ //
+ // // Move is guaranteed efficient
+ // absl::btree_map<int, std::string> map5(std::move(map4));
+ //
+ // * Move assignment operator
+ //
+ // // May be efficient if allocators are compatible
+ // absl::btree_map<int, std::string> map6;
+ // map6 = std::move(map5);
+ //
+ // * Range constructor
+ //
+ // std::vector<std::pair<int, std::string>> v = {{1, "a"}, {2, "b"}};
+ // absl::btree_map<int, std::string> map7(v.begin(), v.end());
+ btree_map() {}
+ using Base::Base;
- // Copy constructor.
- btree_map(const self_type &x)
- : super_type(x) {
- }
+ // btree_map::begin()
+ //
+ // Returns an iterator to the beginning of the `btree_map`.
+ using Base::begin;
- // Range constructor.
- template <class InputIterator>
- btree_map(InputIterator b, InputIterator e,
- const key_compare &comp = key_compare(),
- const allocator_type &alloc = allocator_type())
- : super_type(b, e, comp, alloc) {
- }
+ // btree_map::cbegin()
+ //
+ // Returns a const iterator to the beginning of the `btree_map`.
+ using Base::cbegin;
+
+ // btree_map::end()
+ //
+ // Returns an iterator to the end of the `btree_map`.
+ using Base::end;
+
+ // btree_map::cend()
+ //
+ // Returns a const iterator to the end of the `btree_map`.
+ using Base::cend;
+
+ // btree_map::empty()
+ //
+ // Returns whether or not the `btree_map` is empty.
+ using Base::empty;
+
+ // btree_map::max_size()
+ //
+ // Returns the largest theoretical possible number of elements within a
+ // `btree_map` under current memory constraints. This value can be thought
+ // of as the largest value of `std::distance(begin(), end())` for a
+ // `btree_map<Key, T>`.
+ using Base::max_size;
+
+ // btree_map::size()
+ //
+ // Returns the number of elements currently within the `btree_map`.
+ using Base::size;
+
+ // btree_map::clear()
+ //
+ // Removes all elements from the `btree_map`. Invalidates any references,
+ // pointers, or iterators referring to contained elements.
+ using Base::clear;
+
+ // btree_map::erase()
+ //
+ // Erases elements within the `btree_map`. If an erase occurs, any references,
+ // pointers, or iterators are invalidated.
+ // Overloads are listed below.
+ //
+ // iterator erase(iterator position):
+ // iterator erase(const_iterator position):
+ //
+ // Erases the element at `position` of the `btree_map`, returning
+ // the iterator pointing to the element after the one that was erased
+ // (or end() if none exists).
+ //
+ // iterator erase(const_iterator first, const_iterator last):
+ //
+ // Erases the elements in the open interval [`first`, `last`), returning
+ // the iterator pointing to the element after the interval that was erased
+ // (or end() if none exists).
+ //
+ // template <typename K> size_type erase(const K& key):
+ //
+ // Erases the element with the matching key, if it exists, returning the
+ // number of elements erased.
+ using Base::erase;
+
+ // btree_map::insert()
+ //
+ // Inserts an element of the specified value into the `btree_map`,
+ // returning an iterator pointing to the newly inserted element, provided that
+ // an element with the given key does not already exist. If an insertion
+ // occurs, any references, pointers, or iterators are invalidated.
+ // Overloads are listed below.
+ //
+ // std::pair<iterator,bool> insert(const value_type& value):
+ //
+ // Inserts a value into the `btree_map`. Returns a pair consisting of an
+ // iterator to the inserted element (or to the element that prevented the
+ // insertion) and a bool denoting whether the insertion took place.
+ //
+ // std::pair<iterator,bool> insert(value_type&& value):
+ //
+ // Inserts a moveable value into the `btree_map`. Returns a pair
+ // consisting of an iterator to the inserted element (or to the element that
+ // prevented the insertion) and a bool denoting whether the insertion took
+ // place.
+ //
+ // iterator insert(const_iterator hint, const value_type& value):
+ // iterator insert(const_iterator hint, value_type&& value):
+ //
+ // Inserts a value, using the position of `hint` as a non-binding suggestion
+ // for where to begin the insertion search. Returns an iterator to the
+ // inserted element, or to the existing element that prevented the
+ // insertion.
+ //
+ // void insert(InputIterator first, InputIterator last):
+ //
+ // Inserts a range of values [`first`, `last`).
+ //
+ // void insert(std::initializer_list<init_type> ilist):
+ //
+ // Inserts the elements within the initializer list `ilist`.
+ using Base::insert;
+
+ // btree_map::emplace()
+ //
+ // Inserts an element of the specified value by constructing it in-place
+ // within the `btree_map`, provided that no element with the given key
+ // already exists.
+ //
+ // The element may be constructed even if there already is an element with the
+ // key in the container, in which case the newly constructed element will be
+ // destroyed immediately. Prefer `try_emplace()` unless your key is not
+ // copyable or moveable.
+ //
+ // If an insertion occurs, any references, pointers, or iterators are
+ // invalidated.
+ using Base::emplace;
+
+ // btree_map::emplace_hint()
+ //
+ // Inserts an element of the specified value by constructing it in-place
+ // within the `btree_map`, using the position of `hint` as a non-binding
+ // suggestion for where to begin the insertion search, and only inserts
+ // provided that no element with the given key already exists.
+ //
+ // The element may be constructed even if there already is an element with the
+ // key in the container, in which case the newly constructed element will be
+ // destroyed immediately. Prefer `try_emplace()` unless your key is not
+ // copyable or moveable.
+ //
+ // If an insertion occurs, any references, pointers, or iterators are
+ // invalidated.
+ using Base::emplace_hint;
+
+ // btree_map::try_emplace()
+ //
+ // Inserts an element of the specified value by constructing it in-place
+ // within the `btree_map`, provided that no element with the given key
+ // already exists. Unlike `emplace()`, if an element with the given key
+ // already exists, we guarantee that no element is constructed.
+ //
+ // If an insertion occurs, any references, pointers, or iterators are
+ // invalidated.
+ //
+ // Overloads are listed below.
+ //
+ // std::pair<iterator, bool> try_emplace(const key_type& k, Args&&... args):
+ // std::pair<iterator, bool> try_emplace(key_type&& k, Args&&... args):
+ //
+ // Inserts (via copy or move) the element of the specified key into the
+ // `btree_map`.
+ //
+ // iterator try_emplace(const_iterator hint,
+ // const key_type& k, Args&&... args):
+ // iterator try_emplace(const_iterator hint, key_type&& k, Args&&... args):
+ //
+ // Inserts (via copy or move) the element of the specified key into the
+ // `btree_map` using the position of `hint` as a non-binding suggestion
+ // for where to begin the insertion search.
+ using Base::try_emplace;
+
+ // btree_map::extract()
+ //
+ // Extracts the indicated element, erasing it in the process, and returns it
+ // as a C++17-compatible node handle. Overloads are listed below.
+ //
+ // node_type extract(const_iterator position):
+ //
+ // Extracts the element at the indicated position and returns a node handle
+ // owning that extracted data.
+ //
+ // template <typename K> node_type extract(const K& x):
+ //
+ // Extracts the element with the key matching the passed key value and
+ // returns a node handle owning that extracted data. If the `btree_map`
+ // does not contain an element with a matching key, this function returns an
+ // empty node handle.
+ //
+ // NOTE: In this context, `node_type` refers to the C++17 concept of a
+ // move-only type that owns and provides access to the elements in associative
+ // containers (https://en.cppreference.com/w/cpp/container/node_handle).
+ // It does NOT refer to the data layout of the underlying btree.
+ using Base::extract;
+
+ // btree_map::merge()
+ //
+ // Extracts elements from a given `source` btree_map into this
+ // `btree_map`. If the destination `btree_map` already contains an
+ // element with an equivalent key, that element is not extracted.
+ using Base::merge;
+
+ // btree_map::swap(btree_map& other)
+ //
+ // Exchanges the contents of this `btree_map` with those of the `other`
+ // btree_map, avoiding invocation of any move, copy, or swap operations on
+ // individual elements.
+ //
+ // All iterators and references on the `btree_map` remain valid, excepting
+ // for the past-the-end iterator, which is invalidated.
+ using Base::swap;
+
+ // btree_map::at()
+ //
+ // Returns a reference to the mapped value of the element with key equivalent
+ // to the passed key.
+ using Base::at;
+
+ // btree_map::contains()
+ //
+ // template <typename K> bool contains(const K& key) const:
+ //
+ // Determines whether an element comparing equal to the given `key` exists
+ // within the `btree_map`, returning `true` if so or `false` otherwise.
+ //
+ // Supports heterogeneous lookup, provided that the map is provided a
+ // compatible heterogeneous comparator.
+ using Base::contains;
+
+ // btree_map::count()
+ //
+ // template <typename K> size_type count(const K& key) const:
+ //
+ // Returns the number of elements comparing equal to the given `key` within
+ // the `btree_map`. Note that this function will return either `1` or `0`
+ // since duplicate elements are not allowed within a `btree_map`.
+ //
+ // Supports heterogeneous lookup, provided that the map is provided a
+ // compatible heterogeneous comparator.
+ using Base::count;
+
+ // btree_map::equal_range()
+ //
+ // Returns a closed range [first, last], defined by a `std::pair` of two
+ // iterators, containing all elements with the passed key in the
+ // `btree_map`.
+ using Base::equal_range;
+
+ // btree_map::find()
+ //
+ // template <typename K> iterator find(const K& key):
+ // template <typename K> const_iterator find(const K& key) const:
+ //
+ // Finds an element with the passed `key` within the `btree_map`.
+ //
+ // Supports heterogeneous lookup, provided that the map is provided a
+ // compatible heterogeneous comparator.
+ using Base::find;
+
+ // btree_map::operator[]()
+ //
+ // Returns a reference to the value mapped to the passed key within the
+ // `btree_map`, performing an `insert()` if the key does not already
+ // exist.
+ //
+ // If an insertion occurs, any references, pointers, or iterators are
+ // invalidated. Otherwise iterators are not affected and references are not
+ // invalidated. Overloads are listed below.
+ //
+ // T& operator[](key_type&& key):
+ // T& operator[](const key_type& key):
+ //
+ // Inserts a value_type object constructed in-place if the element with the
+ // given key does not exist.
+ using Base::operator[];
+
+ // btree_map::get_allocator()
+ //
+ // Returns the allocator function associated with this `btree_map`.
+ using Base::get_allocator;
+
+ // btree_map::key_comp();
+ //
+ // Returns the key comparator associated with this `btree_map`.
+ using Base::key_comp;
+
+ // btree_map::value_comp();
+ //
+ // Returns the value comparator associated with this `btree_map`.
+ using Base::value_comp;
};
-template <typename K, typename V, typename C, typename A, int N>
-inline void swap(btree_map<K, V, C, A, N> &x,
- btree_map<K, V, C, A, N> &y) {
- x.swap(y);
+// absl::swap(absl::btree_map<>, absl::btree_map<>)
+//
+// Swaps the contents of two `absl::btree_map` containers.
+template <typename K, typename V, typename C, typename A>
+void swap(btree_map<K, V, C, A> &x, btree_map<K, V, C, A> &y) {
+ return x.swap(y);
}
-// The btree_multimap class is needed mainly for its constructors.
-template <typename Key, typename Value,
- typename Compare = std::less<Key>,
- typename Alloc = std::allocator<std::pair<const Key, Value> >,
- int TargetNodeSize = 256>
-class btree_multimap : public btree_multi_container<
- btree<btree_map_params<Key, Value, Compare, Alloc, TargetNodeSize> > > {
+// absl::erase_if(absl::btree_map<>, Pred)
+//
+// Erases all elements that satisfy the predicate pred from the container.
+template <typename K, typename V, typename C, typename A, typename Pred>
+void erase_if(btree_map<K, V, C, A> &map, Pred pred) {
+ for (auto it = map.begin(); it != map.end();) {
+ if (pred(*it)) {
+ it = map.erase(it);
+ } else {
+ ++it;
+ }
+ }
+}
- typedef btree_multimap<Key, Value, Compare, Alloc, TargetNodeSize> self_type;
- typedef btree_map_params<
- Key, Value, Compare, Alloc, TargetNodeSize> params_type;
- typedef btree<params_type> btree_type;
- typedef btree_multi_container<btree_type> super_type;
+// absl::btree_multimap
+//
+// An `absl::btree_multimap<K, V>` is an ordered associative container of
+// keys and associated values designed to be a more efficient replacement for
+// `std::multimap` (in most cases). Unlike `absl::btree_map`, a B-tree multimap
+// allows multiple elements with equivalent keys.
+//
+// Keys are sorted using an (optional) comparison function, which defaults to
+// `std::less<K>`.
+//
+// An `absl::btree_multimap<K, V>` uses a default allocator of
+// `std::allocator<std::pair<const K, V>>` to allocate (and deallocate)
+// nodes, and construct and destruct values within those nodes. You may
+// instead specify a custom allocator `A` (which in turn requires specifying a
+// custom comparator `C`) as in `absl::btree_multimap<K, V, C, A>`.
+//
+template <typename Key, typename Value, typename Compare = std::less<Key>,
+ typename Alloc = std::allocator<std::pair<const Key, Value>>>
+class btree_multimap
+ : public container_internal::btree_multimap_container<
+ container_internal::btree<container_internal::map_params<
+ Key, Value, Compare, Alloc, /*TargetNodeSize=*/256,
+ /*Multi=*/true>>> {
+ using Base = typename btree_multimap::btree_multimap_container;
public:
- typedef typename btree_type::key_compare key_compare;
- typedef typename btree_type::allocator_type allocator_type;
- typedef typename btree_type::data_type data_type;
- typedef typename btree_type::mapped_type mapped_type;
+ // Constructors and Assignment Operators
+ //
+ // A `btree_multimap` supports the same overload set as `std::multimap`
+ // for construction and assignment:
+ //
+ // * Default constructor
+ //
+ // absl::btree_multimap<int, std::string> map1;
+ //
+ // * Initializer List constructor
+ //
+ // absl::btree_multimap<int, std::string> map2 =
+ // {{1, "huey"}, {2, "dewey"}, {3, "louie"},};
+ //
+ // * Copy constructor
+ //
+ // absl::btree_multimap<int, std::string> map3(map2);
+ //
+ // * Copy assignment operator
+ //
+ // absl::btree_multimap<int, std::string> map4;
+ // map4 = map3;
+ //
+ // * Move constructor
+ //
+ // // Move is guaranteed efficient
+ // absl::btree_multimap<int, std::string> map5(std::move(map4));
+ //
+ // * Move assignment operator
+ //
+ // // May be efficient if allocators are compatible
+ // absl::btree_multimap<int, std::string> map6;
+ // map6 = std::move(map5);
+ //
+ // * Range constructor
+ //
+ // std::vector<std::pair<int, std::string>> v = {{1, "a"}, {2, "b"}};
+ // absl::btree_multimap<int, std::string> map7(v.begin(), v.end());
+ btree_multimap() {}
+ using Base::Base;
- public:
- // Default constructor.
- btree_multimap(const key_compare &comp = key_compare(),
- const allocator_type &alloc = allocator_type())
- : super_type(comp, alloc) {
- }
+ // btree_multimap::begin()
+ //
+ // Returns an iterator to the beginning of the `btree_multimap`.
+ using Base::begin;
- // Copy constructor.
- btree_multimap(const self_type &x)
- : super_type(x) {
- }
+ // btree_multimap::cbegin()
+ //
+ // Returns a const iterator to the beginning of the `btree_multimap`.
+ using Base::cbegin;
- // Range constructor.
- template <class InputIterator>
- btree_multimap(InputIterator b, InputIterator e,
- const key_compare &comp = key_compare(),
- const allocator_type &alloc = allocator_type())
- : super_type(b, e, comp, alloc) {
- }
+ // btree_multimap::end()
+ //
+ // Returns an iterator to the end of the `btree_multimap`.
+ using Base::end;
+
+ // btree_multimap::cend()
+ //
+ // Returns a const iterator to the end of the `btree_multimap`.
+ using Base::cend;
+
+ // btree_multimap::empty()
+ //
+ // Returns whether or not the `btree_multimap` is empty.
+ using Base::empty;
+
+ // btree_multimap::max_size()
+ //
+ // Returns the largest theoretical possible number of elements within a
+ // `btree_multimap` under current memory constraints. This value can be
+ // thought of as the largest value of `std::distance(begin(), end())` for a
+ // `btree_multimap<Key, T>`.
+ using Base::max_size;
+
+ // btree_multimap::size()
+ //
+ // Returns the number of elements currently within the `btree_multimap`.
+ using Base::size;
+
+ // btree_multimap::clear()
+ //
+ // Removes all elements from the `btree_multimap`. Invalidates any references,
+ // pointers, or iterators referring to contained elements.
+ using Base::clear;
+
+ // btree_multimap::erase()
+ //
+ // Erases elements within the `btree_multimap`. If an erase occurs, any
+ // references, pointers, or iterators are invalidated.
+ // Overloads are listed below.
+ //
+ // iterator erase(iterator position):
+ // iterator erase(const_iterator position):
+ //
+ // Erases the element at `position` of the `btree_multimap`, returning
+ // the iterator pointing to the element after the one that was erased
+ // (or end() if none exists).
+ //
+ // iterator erase(const_iterator first, const_iterator last):
+ //
+ // Erases the elements in the open interval [`first`, `last`), returning
+ // the iterator pointing to the element after the interval that was erased
+ // (or end() if none exists).
+ //
+ // template <typename K> size_type erase(const K& key):
+ //
+ // Erases the elements matching the key, if any exist, returning the
+ // number of elements erased.
+ using Base::erase;
+
+ // btree_multimap::insert()
+ //
+ // Inserts an element of the specified value into the `btree_multimap`,
+ // returning an iterator pointing to the newly inserted element.
+ // Any references, pointers, or iterators are invalidated. Overloads are
+ // listed below.
+ //
+ // iterator insert(const value_type& value):
+ //
+ // Inserts a value into the `btree_multimap`, returning an iterator to the
+ // inserted element.
+ //
+ // iterator insert(value_type&& value):
+ //
+ // Inserts a moveable value into the `btree_multimap`, returning an iterator
+ // to the inserted element.
+ //
+ // iterator insert(const_iterator hint, const value_type& value):
+ // iterator insert(const_iterator hint, value_type&& value):
+ //
+ // Inserts a value, using the position of `hint` as a non-binding suggestion
+ // for where to begin the insertion search. Returns an iterator to the
+ // inserted element.
+ //
+ // void insert(InputIterator first, InputIterator last):
+ //
+ // Inserts a range of values [`first`, `last`).
+ //
+ // void insert(std::initializer_list<init_type> ilist):
+ //
+ // Inserts the elements within the initializer list `ilist`.
+ using Base::insert;
+
+ // btree_multimap::emplace()
+ //
+ // Inserts an element of the specified value by constructing it in-place
+ // within the `btree_multimap`. Any references, pointers, or iterators are
+ // invalidated.
+ using Base::emplace;
+
+ // btree_multimap::emplace_hint()
+ //
+ // Inserts an element of the specified value by constructing it in-place
+ // within the `btree_multimap`, using the position of `hint` as a non-binding
+ // suggestion for where to begin the insertion search.
+ //
+ // Any references, pointers, or iterators are invalidated.
+ using Base::emplace_hint;
+
+ // btree_multimap::extract()
+ //
+ // Extracts the indicated element, erasing it in the process, and returns it
+ // as a C++17-compatible node handle. Overloads are listed below.
+ //
+ // node_type extract(const_iterator position):
+ //
+ // Extracts the element at the indicated position and returns a node handle
+ // owning that extracted data.
+ //
+ // template <typename K> node_type extract(const K& x):
+ //
+ // Extracts the element with the key matching the passed key value and
+ // returns a node handle owning that extracted data. If the `btree_multimap`
+ // does not contain an element with a matching key, this function returns an
+ // empty node handle.
+ //
+ // NOTE: In this context, `node_type` refers to the C++17 concept of a
+ // move-only type that owns and provides access to the elements in associative
+ // containers (https://en.cppreference.com/w/cpp/container/node_handle).
+ // It does NOT refer to the data layout of the underlying btree.
+ using Base::extract;
+
+ // btree_multimap::merge()
+ //
+ // Extracts elements from a given `source` btree_multimap into this
+ // `btree_multimap`. If the destination `btree_multimap` already contains an
+ // element with an equivalent key, that element is not extracted.
+ using Base::merge;
+
+ // btree_multimap::swap(btree_multimap& other)
+ //
+ // Exchanges the contents of this `btree_multimap` with those of the `other`
+ // btree_multimap, avoiding invocation of any move, copy, or swap operations
+ // on individual elements.
+ //
+ // All iterators and references on the `btree_multimap` remain valid,
+ // excepting for the past-the-end iterator, which is invalidated.
+ using Base::swap;
+
+ // btree_multimap::contains()
+ //
+ // template <typename K> bool contains(const K& key) const:
+ //
+ // Determines whether an element comparing equal to the given `key` exists
+ // within the `btree_multimap`, returning `true` if so or `false` otherwise.
+ //
+ // Supports heterogeneous lookup, provided that the map is provided a
+ // compatible heterogeneous comparator.
+ using Base::contains;
+
+ // btree_multimap::count()
+ //
+ // template <typename K> size_type count(const K& key) const:
+ //
+ // Returns the number of elements comparing equal to the given `key` within
+ // the `btree_multimap`.
+ //
+ // Supports heterogeneous lookup, provided that the map is provided a
+ // compatible heterogeneous comparator.
+ using Base::count;
+
+ // btree_multimap::equal_range()
+ //
+ // Returns a closed range [first, last], defined by a `std::pair` of two
+ // iterators, containing all elements with the passed key in the
+ // `btree_multimap`.
+ using Base::equal_range;
+
+ // btree_multimap::find()
+ //
+ // template <typename K> iterator find(const K& key):
+ // template <typename K> const_iterator find(const K& key) const:
+ //
+ // Finds an element with the passed `key` within the `btree_multimap`.
+ //
+ // Supports heterogeneous lookup, provided that the map is provided a
+ // compatible heterogeneous comparator.
+ using Base::find;
+
+ // btree_multimap::get_allocator()
+ //
+ // Returns the allocator function associated with this `btree_multimap`.
+ using Base::get_allocator;
+
+ // btree_multimap::key_comp();
+ //
+ // Returns the key comparator associated with this `btree_multimap`.
+ using Base::key_comp;
+
+ // btree_multimap::value_comp();
+ //
+ // Returns the value comparator associated with this `btree_multimap`.
+ using Base::value_comp;
};
-template <typename K, typename V, typename C, typename A, int N>
-inline void swap(btree_multimap<K, V, C, A, N> &x,
- btree_multimap<K, V, C, A, N> &y) {
- x.swap(y);
+// absl::swap(absl::btree_multimap<>, absl::btree_multimap<>)
+//
+// Swaps the contents of two `absl::btree_multimap` containers.
+template <typename K, typename V, typename C, typename A>
+void swap(btree_multimap<K, V, C, A> &x, btree_multimap<K, V, C, A> &y) {
+ return x.swap(y);
+}
+
+// absl::erase_if(absl::btree_multimap<>, Pred)
+//
+// Erases all elements that satisfy the predicate pred from the container.
+template <typename K, typename V, typename C, typename A, typename Pred>
+void erase_if(btree_multimap<K, V, C, A> &map, Pred pred) {
+ for (auto it = map.begin(); it != map.end();) {
+ if (pred(*it)) {
+ it = map.erase(it);
+ } else {
+ ++it;
+ }
+ }
}
-} // namespace btree
+ABSL_NAMESPACE_END
+} // namespace absl
-#endif // UTIL_BTREE_BTREE_MAP_H__
+#endif // ABSL_CONTAINER_BTREE_MAP_H_
projects / ceph.git / commitdiff