Unordered: Implement reserve. Refs #6857.

[SVN r78365]
2025-07-29 19:07:15 +02:00 · 2012-05-07 10:58:32 +00:00
parent 275b03e76b
commit 32dc45b7bd
7 changed files with 133 additions and 2 deletions
--- a/doc/changes.qbk
+++ b/doc/changes.qbk
@ -178,6 +178,8 @@ C++11 support has resulted in some breaking changes:
 [h2 Boost 1.50.0]

 * Fix equality for `unordered_multiset` and `unordered_multimap`.
+* [@https://svn.boost.org/trac/boost/ticket/6857 Ticket 6857]:
+  Implement `reserve`.
 * [@https://svn.boost.org/trac/boost/ticket/6771 Ticket 6771]:
  Avoid gcc's `-Wfloat-equal` warning.
 * [@https://svn.boost.org/trac/boost/ticket/6784 Ticket 6784]:
--- a/doc/ref.php
+++ b/doc/ref.php
@ -963,6 +963,18 @@ EOL;
                <para>The function has no effect if an exception is thrown, unless it is thrown by the container's hash function or comparison function.</para>
              </throws>
            </method>
+            <method name="reserve">
+              <parameter name="n">
+                <paramtype>size_type</paramtype>
+              </parameter>
+              <type>void</type>
+              <description>
+                <para>Invalidates iterators, and changes the order of elements. Pointers and references to elements are not invalidated.</para>
+              </description>
+              <throws>
+                <para>The function has no effect if an exception is thrown, unless it is thrown by the container's hash function or comparison function.</para>
+              </throws>
+            </method>
          </method-group>
          <free-function-group name="Equality Comparisons">
            <function name="operator==">
--- a/doc/ref.xml
+++ b/doc/ref.xml
@ -846,6 +846,18 @@ file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
                <para>The function has no effect if an exception is thrown, unless it is thrown by the container's hash function or comparison function.</para>
              </throws>
            </method>
+            <method name="reserve">
+              <parameter name="n">
+                <paramtype>size_type</paramtype>
+              </parameter>
+              <type>void</type>
+              <description>
+                <para>Invalidates iterators, and changes the order of elements. Pointers and references to elements are not invalidated.</para>
+              </description>
+              <throws>
+                <para>The function has no effect if an exception is thrown, unless it is thrown by the container's hash function or comparison function.</para>
+              </throws>
+            </method>
          </method-group>
          <free-function-group name="Equality Comparisons">
            <function name="operator==">
@ -1797,6 +1809,18 @@ file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
                <para>The function has no effect if an exception is thrown, unless it is thrown by the container's hash function or comparison function.</para>
              </throws>
            </method>
+            <method name="reserve">
+              <parameter name="n">
+                <paramtype>size_type</paramtype>
+              </parameter>
+              <type>void</type>
+              <description>
+                <para>Invalidates iterators, and changes the order of elements. Pointers and references to elements are not invalidated.</para>
+              </description>
+              <throws>
+                <para>The function has no effect if an exception is thrown, unless it is thrown by the container's hash function or comparison function.</para>
+              </throws>
+            </method>
          </method-group>
          <free-function-group name="Equality Comparisons">
            <function name="operator==">
@ -2793,6 +2817,18 @@ file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
                <para>The function has no effect if an exception is thrown, unless it is thrown by the container's hash function or comparison function.</para>
              </throws>
            </method>
+            <method name="reserve">
+              <parameter name="n">
+                <paramtype>size_type</paramtype>
+              </parameter>
+              <type>void</type>
+              <description>
+                <para>Invalidates iterators, and changes the order of elements. Pointers and references to elements are not invalidated.</para>
+              </description>
+              <throws>
+                <para>The function has no effect if an exception is thrown, unless it is thrown by the container's hash function or comparison function.</para>
+              </throws>
+            </method>
          </method-group>
          <free-function-group name="Equality Comparisons">
            <function name="operator==">
@ -3758,6 +3794,18 @@ file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
                <para>The function has no effect if an exception is thrown, unless it is thrown by the container's hash function or comparison function.</para>
              </throws>
            </method>
+            <method name="reserve">
+              <parameter name="n">
+                <paramtype>size_type</paramtype>
+              </parameter>
+              <type>void</type>
+              <description>
+                <para>Invalidates iterators, and changes the order of elements. Pointers and references to elements are not invalidated.</para>
+              </description>
+              <throws>
+                <para>The function has no effect if an exception is thrown, unless it is thrown by the container's hash function or comparison function.</para>
+              </throws>
+            </method>
          </method-group>
          <free-function-group name="Equality Comparisons">
            <function name="operator==">
--- a/include/boost/unordered/detail/table.hpp
+++ b/include/boost/unordered/detail/table.hpp
@ -387,6 +387,7 @@ namespace boost { namespace unordered { namespace detail {

        void reserve_for_insert(std::size_t);
        void rehash(std::size_t);
+        void reserve(std::size_t);
    };

    ////////////////////////////////////////////////////////////////////////////
@ -402,7 +403,9 @@ namespace boost { namespace unordered { namespace detail {
            this->create_buckets();
            this->max_load_ = this->calculate_max_load();
        }
-        else if(size >= max_load_) {
+        // According to the standard this should be 'size >= max_load_',
+        // but I think this is better, defect report filed.
+        else if(size > max_load_) {
            std::size_t num_buckets
                = this->min_buckets_for_size((std::max)(size,
                    this->size_ + (this->size_ >> 1)));
@ -417,7 +420,7 @@ namespace boost { namespace unordered { namespace detail {
    // strong otherwise.

    template <typename Types>
-    void table<Types>::rehash(std::size_t min_buckets)
+    inline void table<Types>::rehash(std::size_t min_buckets)
    {
        using namespace std;

@ -437,6 +440,13 @@ namespace boost { namespace unordered { namespace detail {
            }
        }
    }
+
+    template <typename Types>
+    inline void table<Types>::reserve(std::size_t num_elements)
+    {
+        rehash(static_cast<std::size_t>(
+            std::ceil(static_cast<double>(num_elements) / this->mlf_)));
+    }
 }}}

 #endif
--- a/include/boost/unordered/unordered_map.hpp
+++ b/include/boost/unordered/unordered_map.hpp
@ -515,6 +515,7 @@ namespace unordered
        float load_factor() const;
        void max_load_factor(float);
        void rehash(size_type);
+        void reserve(size_type);

 #if !BOOST_WORKAROUND(__BORLANDC__, < 0x0582)
        friend bool operator==<K,T,H,P,A>(
@ -997,6 +998,7 @@ namespace unordered
        float load_factor() const;
        void max_load_factor(float);
        void rehash(size_type);
+        void reserve(size_type);

 #if !BOOST_WORKAROUND(__BORLANDC__, < 0x0582)
        friend bool operator==<K,T,H,P,A>(
@ -1300,6 +1302,12 @@ namespace unordered
        table_.rehash(n);
    }

+    template <class K, class T, class H, class P, class A>
+    void unordered_map<K,T,H,P,A>::reserve(size_type n)
+    {
+        table_.reserve(n);
+    }
+
    template <class K, class T, class H, class P, class A>
    inline bool operator==(
            unordered_map<K,T,H,P,A> const& m1,
@ -1606,6 +1614,12 @@ namespace unordered
        table_.rehash(n);
    }

+    template <class K, class T, class H, class P, class A>
+    void unordered_multimap<K,T,H,P,A>::reserve(size_type n)
+    {
+        table_.reserve(n);
+    }
+
    template <class K, class T, class H, class P, class A>
    inline bool operator==(
            unordered_multimap<K,T,H,P,A> const& m1,
--- a/include/boost/unordered/unordered_set.hpp
+++ b/include/boost/unordered/unordered_set.hpp
@ -500,6 +500,7 @@ namespace unordered
        float load_factor() const;
        void max_load_factor(float);
        void rehash(size_type);
+        void reserve(size_type);

 #if !BOOST_WORKAROUND(__BORLANDC__, < 0x0582)
        friend bool operator==<T,H,P,A>(
@ -972,6 +973,7 @@ namespace unordered
        float load_factor() const;
        void max_load_factor(float);
        void rehash(size_type);
+        void reserve(size_type);

 #if !BOOST_WORKAROUND(__BORLANDC__, < 0x0582)
        friend bool operator==<T,H,P,A>(
@ -1226,6 +1228,12 @@ namespace unordered
        table_.rehash(n);
    }

+    template <class T, class H, class P, class A>
+    void unordered_set<T,H,P,A>::reserve(size_type n)
+    {
+        table_.reserve(n);
+    }
+
    template <class T, class H, class P, class A>
    inline bool operator==(
            unordered_set<T,H,P,A> const& m1,
@ -1504,6 +1512,12 @@ namespace unordered
        table_.rehash(n);
    }

+    template <class T, class H, class P, class A>
+    void unordered_multiset<T,H,P,A>::reserve(size_type n)
+    {
+        table_.reserve(n);
+    }
+
    template <class T, class H, class P, class A>
    inline bool operator==(
            unordered_multiset<T,H,P,A> const& m1,
--- a/test/unordered/rehash_tests.cpp
+++ b/test/unordered/rehash_tests.cpp
@ -100,6 +100,34 @@ void rehash_test1(X* = 0,
    tracker.compare(x);
 }

+template <class X>
+void reserve_test(X* = 0,
+    test::random_generator generator = test::default_generator)
+{
+    for (int random_mlf = 0; random_mlf < 2; ++random_mlf)
+    {
+        for (int i = 0; i < 2000; i += i < 50 ? 1 : 13)
+        {
+            test::random_values<X> v(i, generator);
+
+            test::ordered<X> tracker;
+            tracker.insert_range(v.begin(), v.end());
+
+            X x;
+            x.max_load_factor(random_mlf ?
+                static_cast<float>(std::rand() % 1000) / 500.0 + 0.5f : 1.0f);
+            // For the current standard this should reserve i+1, I've
+            // submitted a defect report and will assume it's a defect
+            // for now.
+            x.reserve(i);
+            std::size_t bucket_count = x.bucket_count();
+            x.insert(v.begin(), v.end());
+            BOOST_TEST(bucket_count == x.bucket_count());
+            tracker.compare(x);
+        }
+    }
+}
+
 boost::unordered_set<int>* int_set_ptr;
 boost::unordered_multiset<int>* int_multiset_ptr;
 boost::unordered_map<int, int>* int_map_ptr;
@ -117,6 +145,9 @@ UNORDERED_TEST(rehash_empty_test3,
 UNORDERED_TEST(rehash_test1,
    ((int_set_ptr)(int_multiset_ptr)(int_map_ptr)(int_multimap_ptr))
 )
+UNORDERED_TEST(reserve_test,
+    ((int_set_ptr)(int_multiset_ptr)(int_map_ptr)(int_multimap_ptr))
+)

 }