common/interval_set: override subset_of for given range

E.g.:
subset_of([5~10,20~5], 0, 100)  -> [5~10,20~5]
subset_of([5~10,20~5], 5, 25)   -> [5~10,20~5]
subset_of([5~10,20~5], 1, 10)   -> [5~5]
subset_of([5~10,20~5], 8, 24)   -> [8~7, 20~4]

Signed-off-by: xie xingguo <xie.xingguo@zte.com.cn>

diff --git a/src/include/btree_interval_set.h b/src/include/btree_interval_set.h
index 828fead2ae0b9a984dfc089c42c5f99ada293863..c0c35e1a2811048683647379b57e0fe07b7c7b3e 100644 (file)
--- a/src/include/btree_interval_set.h
+++ b/src/include/btree_interval_set.h
@@ -514,6 +514,48 @@ class btree_interval_set {
     return true;
   }
 
+  /*
+   * build a subset of @other for given range [@start, @end)
+   * E.g.:
+   * subset_of([5~10,20~5], 0, 100) -> [5~10,20~5]
+   * subset_of([5~10,20~5], 5, 25)  -> [5~10,20~5]
+   * subset_of([5~10,20~5], 1, 10)  -> [5~5]
+   * subset_of([5~10,20~5], 8, 24)  -> [8~7, 20~4]
+   */
+  void subset_of(const btree_interval_set &other, T start, T end) {
+    assert(end >= start);
+    clear();
+    if (end == start) {
+      return;
+    }
+    typename map_t::const_iterator p = other.find_inc(start);
+    if (p == other.m.end())
+      return;
+    if (p->first < start) {
+      if (p->first + p->second >= end) {
+        insert(start, end - start);
+        return;
+      } else {
+        insert(start, p->first + p->second - start);
+        ++p;
+      }
+    }
+    while (p != other.m.end()) {
+      assert(p->first >= start);
+      if (p->first >= end) {
+        return;
+      }
+      if (p->first + p->second >= end) {
+        insert(p->first, end - p->first);
+        return;
+      } else {
+        // whole
+        insert(p->first, p->second);
+        ++p;
+      }
+    }
+  }
+
   /*
    * build a subset of @other, starting at or after @start, and including
    * @len worth of values, skipping holes.  e.g.,

diff --git a/src/include/interval_set.h b/src/include/interval_set.h
index 67b7ac2e53e3b1f3d6092278eb5b486256f4a240..ee6da3a87dd92cd849459d76d1545b4ce123fca2 100644 (file)
--- a/src/include/interval_set.h
+++ b/src/include/interval_set.h
@@ -660,6 +660,48 @@ class interval_set {
     return true;
   }  
 
+ /*
+   * build a subset of @other for given rage [@start, @end)
+   * E.g.:
+   * subset_of([5~10,20~5], 0, 100) -> [5~10,20~5]
+   * subset_of([5~10,20~5], 5, 25)  -> [5~10,20~5]
+   * subset_of([5~10,20~5], 1, 10)  -> [5~5]
+   * subset_of([5~10,20~5], 8, 24)  -> [8~7, 20~4]
+   */
+  void subset_of(const interval_set &other, T start, T end) {
+    assert(end >= start);
+    clear();
+    if (end == start) {
+      return;
+    }
+    typename std::map<T,T>::const_iterator p = other.find_inc(start);
+    if (p == other.m.end())
+      return;
+    if (p->first < start) {
+      if (p->first + p->second >= end) {
+        insert(start, end - start);
+        return;
+      } else {
+        insert(start, p->first + p->second - start);
+        ++p;
+      }
+    }
+    while (p != other.m.end()) {
+      assert(p->first >= start);
+      if (p->first >= end) {
+        return;
+      }
+      if (p->first + p->second >= end) {
+        insert(p->first, end - p->first);
+        return;
+      } else {
+        // whole
+        insert(p->first, p->second);
+        ++p;
+      }
+    }
+  }
+
   /*
    * build a subset of @other, starting at or after @start, and including
    * @len worth of values, skipping holes.  e.g.,

diff --git a/src/test/common/test_interval_set.cc b/src/test/common/test_interval_set.cc
index f44f35e316fa22f5687a776691dafa0fc31ad482..ca723125610df65466e119bd35f27b431e2f4801 100644 (file)
--- a/src/test/common/test_interval_set.cc
+++ b/src/test/common/test_interval_set.cc
@@ -557,6 +557,53 @@ TYPED_TEST(IntervalSetTest, subset_of) {
   iset1.insert( 50, 5);
   iset2.insert( 55, 2);
   ASSERT_FALSE(iset1.subset_of(iset2));
+
+  ISet iset3, iset4, expected;
+  iset3.insert(5, 10);
+  iset3.insert(20, 5);
+
+  iset4.subset_of(iset3, 0, 100);
+  expected.insert(5, 10);
+  expected.insert(20, 5);
+  ASSERT_TRUE(iset4 == expected);
+
+  iset4.clear();
+  iset4.subset_of(iset3, 5, 25);
+  ASSERT_TRUE(iset4 == expected);
+
+  iset4.clear();
+  iset4.subset_of(iset3, 1, 10);
+  expected.clear();
+  expected.insert(5, 5);
+  ASSERT_TRUE(iset4 == expected);
+
+  iset4.clear();
+  iset4.subset_of(iset3, 8, 24);
+  expected.clear();
+  expected.insert(8, 7);
+  expected.insert(20, 4);
+  ASSERT_TRUE(iset4 == expected);
+
+  iset4.clear();
+  iset4.subset_of(iset3, 0, 0);
+  expected.clear();
+  ASSERT_TRUE(iset4 == expected);
+
+  iset4.clear();
+  iset4.subset_of(iset3, 0, 1);
+  ASSERT_TRUE(iset4 == expected);
+
+  iset4.clear();
+  iset4.subset_of(iset3, 0, 5);
+  ASSERT_TRUE(iset4 == expected);
+
+  iset4.clear();
+  iset4.subset_of(iset3, 25, 30);
+  ASSERT_TRUE(iset4 == expected);
+
+  iset4.clear();
+  iset4.subset_of(iset3, 26, 40);
+  ASSERT_TRUE(iset4 == expected);
 }
 
 TYPED_TEST(IntervalSetTest, span_of) {
@@ -592,4 +639,4 @@ TYPED_TEST(IntervalSetTest, span_of) {
   iset1.span_of( iset2, 100, 5 );
   ASSERT_EQ( iset1.num_intervals(), 0);
   ASSERT_EQ( iset1.size(), 0);
-}
\ No newline at end of file
+}