[Boost-commit] svn:boost r52224 - trunk/boost/unordered/detail

Subject: [Boost-commit] svn:boost r52224 - trunk/boost/unordered/detail
From: daniel_james_at_[hidden]
Date: 2009-04-06 18:51:37

Author: danieljames
Date: 2009-04-06 18:51:36 EDT (Mon, 06 Apr 2009)
New Revision: 52224
URL: http://svn.boost.org/trac/boost/changeset/52224

Log:
Avoid an unnecessary copy in 'operator[]'
Text files modified: 
   trunk/boost/unordered/detail/hash_table_impl.hpp |    18 +++++++++++++++++-                      
   1 files changed, 17 insertions(+), 1 deletions(-)

Modified: trunk/boost/unordered/detail/hash_table_impl.hpp
==============================================================================
--- trunk/boost/unordered/detail/hash_table_impl.hpp	(original)
+++ trunk/boost/unordered/detail/hash_table_impl.hpp	2009-04-06 18:51:36 EDT (Mon, 06 Apr 2009)
@@ -215,6 +215,22 @@
                 }
 #endif
 
+                template <typename K, typename M>
+                void construct_pair(K const& k, M*)
+                {
+                    BOOST_ASSERT(!node_);
+                    node_constructed_ = false;
+                    value_constructed_ = false;
+
+                    node_ = allocators_.node_alloc_.allocate(1);
+
+                    allocators_.node_alloc_.construct(node_, node());
+                    node_constructed_ = true;
+
+                    new(node_->address()) value_type(k, M());
+                    value_constructed_ = true;
+                }
+
                 node_ptr get() const
                 {
                     BOOST_ASSERT(node_);
@@ -1757,7 +1773,7 @@
                     // Create the node before rehashing in case it throws an
                     // exception (need strong safety in such a case).
                     node_constructor a(data_.allocators_);
-                    a.construct(value_type(k, mapped_type()));
+                    a.construct_pair(k, (mapped_type*) 0);
 
                     // reserve has basic exception safety if the hash function
                     // throws, strong otherwise.