interval_set: add lower_bound(T k) member function

Returns an interval pointing to the first interval in the set,
whose last element is not considered to go before k.

Signed-off-by: Yan, Zheng <zyan@redhat.com>

diff --git a/src/include/interval_set.h b/src/include/interval_set.h
index 9a7d2f2e104a636714dddd40a7be062c65a93318..00ead9dcfa44e52fa03fc99d75fb8c1ee3606465 100644 (file)
--- a/src/include/interval_set.h
+++ b/src/include/interval_set.h
@@ -164,6 +164,10 @@ class interval_set {
     return typename interval_set<T>::iterator(m.begin());
   }
 
+  typename interval_set<T>::iterator lower_bound(T start) {
+    return typename interval_set<T>::iterator(find_inc_m(start));
+  }
+
   typename interval_set<T>::iterator end() {
     return typename interval_set<T>::iterator(m.end());
   }
@@ -172,6 +176,10 @@ class interval_set {
     return typename interval_set<T>::const_iterator(m.begin());
   }
 
+  typename interval_set<T>::const_iterator lower_bound(T start) const {
+    return typename interval_set<T>::const_iterator(find_inc(start));
+  }
+
   typename interval_set<T>::const_iterator end() const {
     return typename interval_set<T>::const_iterator(m.end());
   }