Fixes #187 ("flat_map::erase and unique keys")

doc/container.qbk

@@ -1341,6 +1341,7 @@ use [*Boost.Container]? There are several reasons for that:
 [section:release_notes_boost_1_78_00 Boost 1.78 Release]
 
 * Fixed bugs/issues:
+   * [@https://github.com/boostorg/container/issues/187    GitHub #187: ['"flat_map::erase and unique keys"]].
    * [@https://github.com/boostorg/container/issues/188    GitHub #188: ['"Build fails when RTTI is disabled"]].
 
 [endsect]

include/boost/container/detail/flat_tree.hpp

@@ -1124,6 +1124,15 @@ class flat_tree
       return ret;
    }
 
+   size_type erase_unique(const key_type& k)
+   {
+      iterator i = this->find(k);
+      size_type ret = static_cast<size_type>(i != this->end());
+      if (ret)
+         this->erase(i);
+      return ret;
+   }
+
    BOOST_CONTAINER_FORCEINLINE iterator erase(const_iterator first, const_iterator last)
    {  return this->m_data.m_seq.erase(first, last);  }
 

include/boost/container/detail/tree.hpp

@@ -1260,6 +1260,15 @@ class tree
    BOOST_CONTAINER_FORCEINLINE size_type erase(const key_type& k)
    {  return AllocHolder::erase_key(k, KeyNodeCompare(key_comp()), alloc_version()); }
 
+   size_type erase_unique(const key_type& k)
+   {
+      iterator i = this->find(k);
+      size_type ret = static_cast<size_type>(i != this->end());
+      if (ret)
+         this->erase(i);
+      return ret;
+   }
+
    iterator erase(const_iterator first, const_iterator last)
    {
       BOOST_ASSERT(first == last || (first != this->cend() && (priv_is_linked)(first)));

include/boost/container/flat_map.hpp

@@ -1265,14 +1265,14 @@ class flat_map
          (m_flat_tree.erase(dtl::force_copy<impl_const_iterator>(p)));
    }
 
-   //! <b>Effects</b>: Erases all elements in the container with key equivalent to x.
+   //! <b>Effects</b>: If present, erases the element in the container with key equivalent to x.
    //!
-   //! <b>Returns</b>: Returns the number of erased elements.
+   //! <b>Returns</b>: Returns the number of erased elements (0/1).
    //!
    //! <b>Complexity</b>: Logarithmic search time plus erasure time
    //!   linear to the elements with bigger keys.
    BOOST_CONTAINER_FORCEINLINE size_type erase(const key_type& x)
-      { return m_flat_tree.erase(x); }
+      { return m_flat_tree.erase_unique(x); }
 
    //! <b>Effects</b>: Erases all the elements in the range [first, last).
    //!

include/boost/container/flat_set.hpp

@@ -767,6 +767,15 @@ class flat_set
    BOOST_CONTAINER_FORCEINLINE void merge(BOOST_RV_REF_BEG flat_multiset<Key, C2, AllocatorOrContainer> BOOST_RV_REF_END source)
    {  return this->merge(static_cast<flat_multiset<Key, C2, AllocatorOrContainer>&>(source));   }
 
+   //! <b>Effects</b>: If present, erases the element in the container with key equivalent to x.
+   //!
+   //! <b>Returns</b>: Returns the number of erased elements (0/1).
+   //!
+   //! <b>Complexity</b>: Logarithmic search time plus erasure time
+   //!   linear to the elements with bigger keys.
+   BOOST_CONTAINER_FORCEINLINE size_type erase(const key_type& x)
+   {  return this->tree_t::erase_unique(x);   }
+
    #if defined(BOOST_CONTAINER_DOXYGEN_INVOKED)
 
    //! <b>Effects</b>: Erases the element pointed to by p.
@@ -781,14 +790,6 @@ class flat_set
    //!   not less than the erased element.
    iterator erase(const_iterator p);
 
-   //! <b>Effects</b>: Erases all elements in the container with key equivalent to x.
-   //!
-   //! <b>Returns</b>: Returns the number of erased elements.
-   //!
-   //! <b>Complexity</b>: Logarithmic search time plus erasure time
-   //!   linear to the elements with bigger keys.
-   size_type erase(const key_type& x);
-
    //! <b>Effects</b>: Erases all the elements in the range [first, last).
    //!
    //! <b>Returns</b>: Returns last.
@@ -909,6 +910,8 @@ class flat_set
    //! <b>Note</b>: Non-standard extension
    size_type index_of(const_iterator p) const BOOST_NOEXCEPT_OR_NOTHROW;
 
+   #else
+   using tree_t::erase;
    #endif   //   #if defined(BOOST_CONTAINER_DOXYGEN_INVOKED)
 
    //! <b>Returns</b>: The number of elements with key equivalent to x.

include/boost/container/map.hpp

@@ -964,6 +964,14 @@ class map
 
    #endif   // !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES)
 
+   //! <b>Effects</b>: If present, erases the element in the container with key equivalent to x.
+   //!
+   //! <b>Returns</b>: Returns the number of erased elements (0/1).
+   //!
+   //! <b>Complexity</b>: log(size()) + count(k)
+   BOOST_CONTAINER_FORCEINLINE size_type erase(const key_type& x)
+      { return this->base_t::erase_unique(x); }
+
    #if defined(BOOST_CONTAINER_DOXYGEN_INVOKED)
 
    //! <b>Effects</b>: Erases the element pointed to by p.
@@ -975,13 +983,6 @@ class map
    //! <b>Complexity</b>: Amortized constant time
    iterator erase(const_iterator p) BOOST_NOEXCEPT_OR_NOTHROW;
 
-   //! <b>Effects</b>: Erases all elements in the container with key equivalent to x.
-   //!
-   //! <b>Returns</b>: Returns the number of erased elements.
-   //!
-   //! <b>Complexity</b>: log(size()) + count(k)
-   size_type erase(const key_type& x) BOOST_NOEXCEPT_OR_NOTHROW;
-
    //! <b>Effects</b>: Erases all the elements in the range [first, last).
    //!
    //! <b>Returns</b>: Returns last.
@@ -989,7 +990,9 @@ class map
    //! <b>Complexity</b>: log(size())+N where N is the distance from first to last.
    iterator erase(const_iterator first, const_iterator last) BOOST_NOEXCEPT_OR_NOTHROW;
 
-   #endif
+   #else
+   using base_t::erase;
+   #endif   //   #if defined(BOOST_CONTAINER_DOXYGEN_INVOKED)
 
    //! <b>Effects</b>: Removes the first element in the container with key equivalent to k.
    //!

include/boost/container/set.hpp

@@ -680,6 +680,14 @@ class set
    BOOST_CONTAINER_FORCEINLINE void merge(BOOST_RV_REF_BEG multiset<Key, C2, Allocator, Options> BOOST_RV_REF_END source)
    {  return this->merge(static_cast<multiset<Key, C2, Allocator, Options>&>(source));   }
 
+   //! <b>Effects</b>: If present, erases the element in the container with key equivalent to x.
+   //!
+   //! <b>Returns</b>: Returns the number of erased elements (0/1).
+   //!
+   //! <b>Complexity</b>: log(size()) + count(k)
+   BOOST_CONTAINER_FORCEINLINE size_type erase(const key_type& x)
+   {  return this->base_t::erase_unique(x);   }
+
    #if defined(BOOST_CONTAINER_DOXYGEN_INVOKED)
 
    //! <b>Effects</b>: Erases the element pointed to by p.
@@ -691,13 +699,6 @@ class set
    //! <b>Complexity</b>: Amortized constant time
    iterator erase(const_iterator p);
 
-   //! <b>Effects</b>: Erases all elements in the container with key equivalent to x.
-   //!
-   //! <b>Returns</b>: Returns the number of erased elements.
-   //!
-   //! <b>Complexity</b>: log(size()) + count(k)
-   size_type erase(const key_type& x);
-
    //! <b>Effects</b>: Erases all the elements in the range [first, last).
    //!
    //! <b>Returns</b>: Returns last.
@@ -771,7 +772,9 @@ class set
    template<typename K>
    const_iterator find(const K& x) const;
 
-   #endif   //#if defined(BOOST_CONTAINER_DOXYGEN_INVOKED)
+   #else
+   using base_t::erase;
+   #endif   //   #if defined(BOOST_CONTAINER_DOXYGEN_INVOKED)
 
    //! <b>Returns</b>: The number of elements with key equivalent to x.
    //!