From 8a9558f06f10e4f6e03294277bf593a2dba37c70 Mon Sep 17 00:00:00 2001
From: Jeremiah Willcock <jewillco@osl.iu.edu>
Date: Wed, 4 Feb 2009 21:01:27 +0000
Subject: [PATCH] Added ability to check whether an element is in the heap, and
 do conditional insert/update operations based on that

[SVN r51021]
---
 include/boost/graph/detail/d_ary_heap.hpp | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/include/boost/graph/detail/d_ary_heap.hpp b/include/boost/graph/detail/d_ary_heap.hpp
index 6a249046..ffbaa47c 100644
--- a/include/boost/graph/detail/d_ary_heap.hpp
+++ b/include/boost/graph/detail/d_ary_heap.hpp
@@ -104,6 +104,7 @@ namespace boost {
     }
 
     void pop() {
+      put(index_in_heap, data[0], (size_type)(-1));
       data[0] = data.back();
       put(index_in_heap, data[0], 0);
       data.pop_back();
@@ -120,6 +121,21 @@ namespace boost {
       verify_heap();
     }
 
+    bool contains(const Value& v) const {
+      return (index != (size_type)(-1));
+    }
+
+    void push_or_update(const Value& v) { /* insert if not present, else update */
+      size_type index = get(index_in_heap, v);
+      if (index == (size_type)(-1)) {
+        index = data.size();
+        data.push_back(v);
+        put(index_in_heap, v, index);
+      }
+      preserve_heap_property_up(index);
+      verify_heap();
+    }
+
     private:
     Compare compare;
     Container data;
@@ -211,6 +227,7 @@ namespace boost {
     // From the root, swap elements (each one with its smallest child) if there
     // are any parent-child pairs that violate the heap property
     void preserve_heap_property_down() {
+      if (data.empty()) return;
       size_type index = 0;
       Value currently_being_moved = data[0];
       distance_type currently_being_moved_dist =