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  1. // Map implementation -*- C++ -*-
  2.  
  3. // Copyright (C) 2001-2015 Free Software Foundation, Inc.
  4. //
  5. // This file is part of the GNU ISO C++ Library.  This library is free
  6. // software; you can redistribute it and/or modify it under the
  7. // terms of the GNU General Public License as published by the
  8. // Free Software Foundation; either version 3, or (at your option)
  9. // any later version.
  10.  
  11. // This library is distributed in the hope that it will be useful,
  12. // but WITHOUT ANY WARRANTY; without even the implied warranty of
  13. // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14. // GNU General Public License for more details.
  15.  
  16. // Under Section 7 of GPL version 3, you are granted additional
  17. // permissions described in the GCC Runtime Library Exception, version
  18. // 3.1, as published by the Free Software Foundation.
  19.  
  20. // You should have received a copy of the GNU General Public License and
  21. // a copy of the GCC Runtime Library Exception along with this program;
  22. // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  23. // <http://www.gnu.org/licenses/>.
  24.  
  25. /*
  26.  *
  27.  * Copyright (c) 1994
  28.  * Hewlett-Packard Company
  29.  *
  30.  * Permission to use, copy, modify, distribute and sell this software
  31.  * and its documentation for any purpose is hereby granted without fee,
  32.  * provided that the above copyright notice appear in all copies and
  33.  * that both that copyright notice and this permission notice appear
  34.  * in supporting documentation.  Hewlett-Packard Company makes no
  35.  * representations about the suitability of this software for any
  36.  * purpose.  It is provided "as is" without express or implied warranty.
  37.  *
  38.  *
  39.  * Copyright (c) 1996,1997
  40.  * Silicon Graphics Computer Systems, Inc.
  41.  *
  42.  * Permission to use, copy, modify, distribute and sell this software
  43.  * and its documentation for any purpose is hereby granted without fee,
  44.  * provided that the above copyright notice appear in all copies and
  45.  * that both that copyright notice and this permission notice appear
  46.  * in supporting documentation.  Silicon Graphics makes no
  47.  * representations about the suitability of this software for any
  48.  * purpose.  It is provided "as is" without express or implied warranty.
  49.  */
  50.  
  51. /** @file bits/stl_map.h
  52.  *  This is an internal header file, included by other library headers.
  53.  *  Do not attempt to use it directly. @headername{map}
  54.  */
  55.  
  56. #ifndef _STL_MAP_H
  57. #define _STL_MAP_H 1
  58.  
  59. #include <bits/functexcept.h>
  60. #include <bits/concept_check.h>
  61. #if __cplusplus >= 201103L
  62. #include <initializer_list>
  63. #include <tuple>
  64. #endif
  65.  
  66. namespace std _GLIBCXX_VISIBILITY(default)
  67. {
  68. _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
  69.  
  70.   /**
  71.    *  @brief A standard container made up of (key,value) pairs, which can be
  72.    *  retrieved based on a key, in logarithmic time.
  73.    *
  74.    *  @ingroup associative_containers
  75.    *
  76.    *  @tparam _Key  Type of key objects.
  77.    *  @tparam  _Tp  Type of mapped objects.
  78.    *  @tparam _Compare  Comparison function object type, defaults to less<_Key>.
  79.    *  @tparam _Alloc  Allocator type, defaults to
  80.    *                  allocator<pair<const _Key, _Tp>.
  81.    *
  82.    *  Meets the requirements of a <a href="tables.html#65">container</a>, a
  83.    *  <a href="tables.html#66">reversible container</a>, and an
  84.    *  <a href="tables.html#69">associative container</a> (using unique keys).
  85.    *  For a @c map<Key,T> the key_type is Key, the mapped_type is T, and the
  86.    *  value_type is std::pair<const Key,T>.
  87.    *
  88.    *  Maps support bidirectional iterators.
  89.    *
  90.    *  The private tree data is declared exactly the same way for map and
  91.    *  multimap; the distinction is made entirely in how the tree functions are
  92.    *  called (*_unique versus *_equal, same as the standard).
  93.   */
  94.   template <typename _Key, typename _Tp, typename _Compare = std::less<_Key>,
  95.             typename _Alloc = std::allocator<std::pair<const _Key, _Tp> > >
  96.     class map
  97.     {
  98.     public:
  99.       typedef _Key                                          key_type;
  100.       typedef _Tp                                           mapped_type;
  101.       typedef std::pair<const _Key, _Tp>                    value_type;
  102.       typedef _Compare                                      key_compare;
  103.       typedef _Alloc                                        allocator_type;
  104.  
  105.     private:
  106.       // concept requirements
  107.       typedef typename _Alloc::value_type                   _Alloc_value_type;
  108.       __glibcxx_class_requires(_Tp, _SGIAssignableConcept)
  109.       __glibcxx_class_requires4(_Compare, bool, _Key, _Key,
  110.                                 _BinaryFunctionConcept)
  111.       __glibcxx_class_requires2(value_type, _Alloc_value_type, _SameTypeConcept)
  112.  
  113.     public:
  114.       class value_compare
  115.       : public std::binary_function<value_type, value_type, bool>
  116.       {
  117.         friend class map<_Key, _Tp, _Compare, _Alloc>;
  118.       protected:
  119.         _Compare comp;
  120.  
  121.         value_compare(_Compare __c)
  122.         : comp(__c) { }
  123.  
  124.       public:
  125.         bool operator()(const value_type& __x, const value_type& __y) const
  126.         { return comp(__x.first, __y.first); }
  127.       };
  128.  
  129.     private:
  130.       /// This turns a red-black tree into a [multi]map.
  131.       typedef typename __gnu_cxx::__alloc_traits<_Alloc>::template
  132.         rebind<value_type>::other _Pair_alloc_type;
  133.  
  134.       typedef _Rb_tree<key_type, value_type, _Select1st<value_type>,
  135.                        key_compare, _Pair_alloc_type> _Rep_type;
  136.  
  137.       /// The actual tree structure.
  138.       _Rep_type _M_t;
  139.  
  140.       typedef __gnu_cxx::__alloc_traits<_Pair_alloc_type> _Alloc_traits;
  141.  
  142.     public:
  143.       // many of these are specified differently in ISO, but the following are
  144.       // "functionally equivalent"
  145.       typedef typename _Alloc_traits::pointer            pointer;
  146.       typedef typename _Alloc_traits::const_pointer      const_pointer;
  147.       typedef typename _Alloc_traits::reference          reference;
  148.       typedef typename _Alloc_traits::const_reference    const_reference;
  149.       typedef typename _Rep_type::iterator               iterator;
  150.       typedef typename _Rep_type::const_iterator         const_iterator;
  151.       typedef typename _Rep_type::size_type              size_type;
  152.       typedef typename _Rep_type::difference_type        difference_type;
  153.       typedef typename _Rep_type::reverse_iterator       reverse_iterator;
  154.       typedef typename _Rep_type::const_reverse_iterator const_reverse_iterator;
  155.  
  156.       // [23.3.1.1] construct/copy/destroy
  157.       // (get_allocator() is also listed in this section)
  158.  
  159.       /**
  160.        *  @brief  Default constructor creates no elements.
  161.        */
  162.       map()
  163. #if __cplusplus >= 201103L
  164.       noexcept(is_nothrow_default_constructible<allocator_type>::value)
  165. #endif
  166.       : _M_t() { }
  167.  
  168.       /**
  169.        *  @brief  Creates a %map with no elements.
  170.        *  @param  __comp  A comparison object.
  171.        *  @param  __a  An allocator object.
  172.        */
  173.       explicit
  174.       map(const _Compare& __comp,
  175.           const allocator_type& __a = allocator_type())
  176.       : _M_t(__comp, _Pair_alloc_type(__a)) { }
  177.  
  178.       /**
  179.        *  @brief  %Map copy constructor.
  180.        *  @param  __x  A %map of identical element and allocator types.
  181.        *
  182.        *  The newly-created %map uses a copy of the allocation object
  183.        *  used by @a __x.
  184.        */
  185.       map(const map& __x)
  186.       : _M_t(__x._M_t) { }
  187.  
  188. #if __cplusplus >= 201103L
  189.       /**
  190.        *  @brief  %Map move constructor.
  191.        *  @param  __x  A %map of identical element and allocator types.
  192.        *
  193.        *  The newly-created %map contains the exact contents of @a __x.
  194.        *  The contents of @a __x are a valid, but unspecified %map.
  195.        */
  196.       map(map&& __x)
  197.       noexcept(is_nothrow_copy_constructible<_Compare>::value)
  198.       : _M_t(std::move(__x._M_t)) { }
  199.  
  200.       /**
  201.        *  @brief  Builds a %map from an initializer_list.
  202.        *  @param  __l  An initializer_list.
  203.        *  @param  __comp  A comparison object.
  204.        *  @param  __a  An allocator object.
  205.        *
  206.        *  Create a %map consisting of copies of the elements in the
  207.        *  initializer_list @a __l.
  208.        *  This is linear in N if the range is already sorted, and NlogN
  209.        *  otherwise (where N is @a __l.size()).
  210.        */
  211.       map(initializer_list<value_type> __l,
  212.           const _Compare& __comp = _Compare(),
  213.           const allocator_type& __a = allocator_type())
  214.       : _M_t(__comp, _Pair_alloc_type(__a))
  215.       { _M_t._M_insert_unique(__l.begin(), __l.end()); }
  216.  
  217.       /// Allocator-extended default constructor.
  218.       explicit
  219.       map(const allocator_type& __a)
  220.       : _M_t(_Compare(), _Pair_alloc_type(__a)) { }
  221.  
  222.       /// Allocator-extended copy constructor.
  223.       map(const map& __m, const allocator_type& __a)
  224.       : _M_t(__m._M_t, _Pair_alloc_type(__a)) { }
  225.  
  226.       /// Allocator-extended move constructor.
  227.       map(map&& __m, const allocator_type& __a)
  228.       noexcept(is_nothrow_copy_constructible<_Compare>::value
  229.                && _Alloc_traits::_S_always_equal())
  230.       : _M_t(std::move(__m._M_t), _Pair_alloc_type(__a)) { }
  231.  
  232.       /// Allocator-extended initialier-list constructor.
  233.       map(initializer_list<value_type> __l, const allocator_type& __a)
  234.       : _M_t(_Compare(), _Pair_alloc_type(__a))
  235.       { _M_t._M_insert_unique(__l.begin(), __l.end()); }
  236.  
  237.       /// Allocator-extended range constructor.
  238.       template<typename _InputIterator>
  239.         map(_InputIterator __first, _InputIterator __last,
  240.             const allocator_type& __a)
  241.         : _M_t(_Compare(), _Pair_alloc_type(__a))
  242.         { _M_t._M_insert_unique(__first, __last); }
  243. #endif
  244.  
  245.       /**
  246.        *  @brief  Builds a %map from a range.
  247.        *  @param  __first  An input iterator.
  248.        *  @param  __last  An input iterator.
  249.        *
  250.        *  Create a %map consisting of copies of the elements from
  251.        *  [__first,__last).  This is linear in N if the range is
  252.        *  already sorted, and NlogN otherwise (where N is
  253.        *  distance(__first,__last)).
  254.        */
  255.       template<typename _InputIterator>
  256.         map(_InputIterator __first, _InputIterator __last)
  257.         : _M_t()
  258.         { _M_t._M_insert_unique(__first, __last); }
  259.  
  260.       /**
  261.        *  @brief  Builds a %map from a range.
  262.        *  @param  __first  An input iterator.
  263.        *  @param  __last  An input iterator.
  264.        *  @param  __comp  A comparison functor.
  265.        *  @param  __a  An allocator object.
  266.        *
  267.        *  Create a %map consisting of copies of the elements from
  268.        *  [__first,__last).  This is linear in N if the range is
  269.        *  already sorted, and NlogN otherwise (where N is
  270.        *  distance(__first,__last)).
  271.        */
  272.       template<typename _InputIterator>
  273.         map(_InputIterator __first, _InputIterator __last,
  274.             const _Compare& __comp,
  275.             const allocator_type& __a = allocator_type())
  276.         : _M_t(__comp, _Pair_alloc_type(__a))
  277.         { _M_t._M_insert_unique(__first, __last); }
  278.  
  279.       // FIXME There is no dtor declared, but we should have something
  280.       // generated by Doxygen.  I don't know what tags to add to this
  281.       // paragraph to make that happen:
  282.       /**
  283.        *  The dtor only erases the elements, and note that if the elements
  284.        *  themselves are pointers, the pointed-to memory is not touched in any
  285.        *  way.  Managing the pointer is the user's responsibility.
  286.        */
  287.  
  288.       /**
  289.        *  @brief  %Map assignment operator.
  290.        *  @param  __x  A %map of identical element and allocator types.
  291.        *
  292.        *  All the elements of @a __x are copied, but unlike the copy
  293.        *  constructor, the allocator object is not copied.
  294.        */
  295.       map&
  296.       operator=(const map& __x)
  297.       {
  298.         _M_t = __x._M_t;
  299.         return *this;
  300.       }
  301.  
  302. #if __cplusplus >= 201103L
  303.       /// Move assignment operator.
  304.       map&
  305.       operator=(map&&) = default;
  306.  
  307.       /**
  308.        *  @brief  %Map list assignment operator.
  309.        *  @param  __l  An initializer_list.
  310.        *
  311.        *  This function fills a %map with copies of the elements in the
  312.        *  initializer list @a __l.
  313.        *
  314.        *  Note that the assignment completely changes the %map and
  315.        *  that the resulting %map's size is the same as the number
  316.        *  of elements assigned.  Old data may be lost.
  317.        */
  318.       map&
  319.       operator=(initializer_list<value_type> __l)
  320.       {
  321.         _M_t._M_assign_unique(__l.begin(), __l.end());
  322.         return *this;
  323.       }
  324. #endif
  325.  
  326.       /// Get a copy of the memory allocation object.
  327.       allocator_type
  328.       get_allocator() const _GLIBCXX_NOEXCEPT
  329.       { return allocator_type(_M_t.get_allocator()); }
  330.  
  331.       // iterators
  332.       /**
  333.        *  Returns a read/write iterator that points to the first pair in the
  334.        *  %map.
  335.        *  Iteration is done in ascending order according to the keys.
  336.        */
  337.       iterator
  338.       begin() _GLIBCXX_NOEXCEPT
  339.       { return _M_t.begin(); }
  340.  
  341.       /**
  342.        *  Returns a read-only (constant) iterator that points to the first pair
  343.        *  in the %map.  Iteration is done in ascending order according to the
  344.        *  keys.
  345.        */
  346.       const_iterator
  347.       begin() const _GLIBCXX_NOEXCEPT
  348.       { return _M_t.begin(); }
  349.  
  350.       /**
  351.        *  Returns a read/write iterator that points one past the last
  352.        *  pair in the %map.  Iteration is done in ascending order
  353.        *  according to the keys.
  354.        */
  355.       iterator
  356.       end() _GLIBCXX_NOEXCEPT
  357.       { return _M_t.end(); }
  358.  
  359.       /**
  360.        *  Returns a read-only (constant) iterator that points one past the last
  361.        *  pair in the %map.  Iteration is done in ascending order according to
  362.        *  the keys.
  363.        */
  364.       const_iterator
  365.       end() const _GLIBCXX_NOEXCEPT
  366.       { return _M_t.end(); }
  367.  
  368.       /**
  369.        *  Returns a read/write reverse iterator that points to the last pair in
  370.        *  the %map.  Iteration is done in descending order according to the
  371.        *  keys.
  372.        */
  373.       reverse_iterator
  374.       rbegin() _GLIBCXX_NOEXCEPT
  375.       { return _M_t.rbegin(); }
  376.  
  377.       /**
  378.        *  Returns a read-only (constant) reverse iterator that points to the
  379.        *  last pair in the %map.  Iteration is done in descending order
  380.        *  according to the keys.
  381.        */
  382.       const_reverse_iterator
  383.       rbegin() const _GLIBCXX_NOEXCEPT
  384.       { return _M_t.rbegin(); }
  385.  
  386.       /**
  387.        *  Returns a read/write reverse iterator that points to one before the
  388.        *  first pair in the %map.  Iteration is done in descending order
  389.        *  according to the keys.
  390.        */
  391.       reverse_iterator
  392.       rend() _GLIBCXX_NOEXCEPT
  393.       { return _M_t.rend(); }
  394.  
  395.       /**
  396.        *  Returns a read-only (constant) reverse iterator that points to one
  397.        *  before the first pair in the %map.  Iteration is done in descending
  398.        *  order according to the keys.
  399.        */
  400.       const_reverse_iterator
  401.       rend() const _GLIBCXX_NOEXCEPT
  402.       { return _M_t.rend(); }
  403.  
  404. #if __cplusplus >= 201103L
  405.       /**
  406.        *  Returns a read-only (constant) iterator that points to the first pair
  407.        *  in the %map.  Iteration is done in ascending order according to the
  408.        *  keys.
  409.        */
  410.       const_iterator
  411.       cbegin() const noexcept
  412.       { return _M_t.begin(); }
  413.  
  414.       /**
  415.        *  Returns a read-only (constant) iterator that points one past the last
  416.        *  pair in the %map.  Iteration is done in ascending order according to
  417.        *  the keys.
  418.        */
  419.       const_iterator
  420.       cend() const noexcept
  421.       { return _M_t.end(); }
  422.  
  423.       /**
  424.        *  Returns a read-only (constant) reverse iterator that points to the
  425.        *  last pair in the %map.  Iteration is done in descending order
  426.        *  according to the keys.
  427.        */
  428.       const_reverse_iterator
  429.       crbegin() const noexcept
  430.       { return _M_t.rbegin(); }
  431.  
  432.       /**
  433.        *  Returns a read-only (constant) reverse iterator that points to one
  434.        *  before the first pair in the %map.  Iteration is done in descending
  435.        *  order according to the keys.
  436.        */
  437.       const_reverse_iterator
  438.       crend() const noexcept
  439.       { return _M_t.rend(); }
  440. #endif
  441.  
  442.       // capacity
  443.       /** Returns true if the %map is empty.  (Thus begin() would equal
  444.        *  end().)
  445.       */
  446.       bool
  447.       empty() const _GLIBCXX_NOEXCEPT
  448.       { return _M_t.empty(); }
  449.  
  450.       /** Returns the size of the %map.  */
  451.       size_type
  452.       size() const _GLIBCXX_NOEXCEPT
  453.       { return _M_t.size(); }
  454.  
  455.       /** Returns the maximum size of the %map.  */
  456.       size_type
  457.       max_size() const _GLIBCXX_NOEXCEPT
  458.       { return _M_t.max_size(); }
  459.  
  460.       // [23.3.1.2] element access
  461.       /**
  462.        *  @brief  Subscript ( @c [] ) access to %map data.
  463.        *  @param  __k  The key for which data should be retrieved.
  464.        *  @return  A reference to the data of the (key,data) %pair.
  465.        *
  466.        *  Allows for easy lookup with the subscript ( @c [] )
  467.        *  operator.  Returns data associated with the key specified in
  468.        *  subscript.  If the key does not exist, a pair with that key
  469.        *  is created using default values, which is then returned.
  470.        *
  471.        *  Lookup requires logarithmic time.
  472.        */
  473.       mapped_type&
  474.       operator[](const key_type& __k)
  475.       {
  476.         // concept requirements
  477.         __glibcxx_function_requires(_DefaultConstructibleConcept<mapped_type>)
  478.  
  479.         iterator __i = lower_bound(__k);
  480.         // __i->first is greater than or equivalent to __k.
  481.         if (__i == end() || key_comp()(__k, (*__i).first))
  482. #if __cplusplus >= 201103L
  483.           __i = _M_t._M_emplace_hint_unique(__i, std::piecewise_construct,
  484.                                             std::tuple<const key_type&>(__k),
  485.                                             std::tuple<>());
  486. #else
  487.           __i = insert(__i, value_type(__k, mapped_type()));
  488. #endif
  489.         return (*__i).second;
  490.       }
  491.  
  492. #if __cplusplus >= 201103L
  493.       mapped_type&
  494.       operator[](key_type&& __k)
  495.       {
  496.         // concept requirements
  497.         __glibcxx_function_requires(_DefaultConstructibleConcept<mapped_type>)
  498.  
  499.         iterator __i = lower_bound(__k);
  500.         // __i->first is greater than or equivalent to __k.
  501.         if (__i == end() || key_comp()(__k, (*__i).first))
  502.           __i = _M_t._M_emplace_hint_unique(__i, std::piecewise_construct,
  503.                                         std::forward_as_tuple(std::move(__k)),
  504.                                         std::tuple<>());
  505.         return (*__i).second;
  506.       }
  507. #endif
  508.  
  509.       // _GLIBCXX_RESOLVE_LIB_DEFECTS
  510.       // DR 464. Suggestion for new member functions in standard containers.
  511.       /**
  512.        *  @brief  Access to %map data.
  513.        *  @param  __k  The key for which data should be retrieved.
  514.        *  @return  A reference to the data whose key is equivalent to @a __k, if
  515.        *           such a data is present in the %map.
  516.        *  @throw  std::out_of_range  If no such data is present.
  517.        */
  518.       mapped_type&
  519.       at(const key_type& __k)
  520.       {
  521.         iterator __i = lower_bound(__k);
  522.         if (__i == end() || key_comp()(__k, (*__i).first))
  523.           __throw_out_of_range(__N("map::at"));
  524.         return (*__i).second;
  525.       }
  526.  
  527.       const mapped_type&
  528.       at(const key_type& __k) const
  529.       {
  530.         const_iterator __i = lower_bound(__k);
  531.         if (__i == end() || key_comp()(__k, (*__i).first))
  532.           __throw_out_of_range(__N("map::at"));
  533.         return (*__i).second;
  534.       }
  535.  
  536.       // modifiers
  537. #if __cplusplus >= 201103L
  538.       /**
  539.        *  @brief Attempts to build and insert a std::pair into the %map.
  540.        *
  541.        *  @param __args  Arguments used to generate a new pair instance (see
  542.        *                std::piecewise_contruct for passing arguments to each
  543.        *                part of the pair constructor).
  544.        *
  545.        *  @return  A pair, of which the first element is an iterator that points
  546.        *           to the possibly inserted pair, and the second is a bool that
  547.        *           is true if the pair was actually inserted.
  548.        *
  549.        *  This function attempts to build and insert a (key, value) %pair into
  550.        *  the %map.
  551.        *  A %map relies on unique keys and thus a %pair is only inserted if its
  552.        *  first element (the key) is not already present in the %map.
  553.        *
  554.        *  Insertion requires logarithmic time.
  555.        */
  556.       template<typename... _Args>
  557.         std::pair<iterator, bool>
  558.         emplace(_Args&&... __args)
  559.         { return _M_t._M_emplace_unique(std::forward<_Args>(__args)...); }
  560.  
  561.       /**
  562.        *  @brief Attempts to build and insert a std::pair into the %map.
  563.        *
  564.        *  @param  __pos  An iterator that serves as a hint as to where the pair
  565.        *                should be inserted.
  566.        *  @param  __args  Arguments used to generate a new pair instance (see
  567.        *                 std::piecewise_contruct for passing arguments to each
  568.        *                 part of the pair constructor).
  569.        *  @return An iterator that points to the element with key of the
  570.        *          std::pair built from @a __args (may or may not be that
  571.        *          std::pair).
  572.        *
  573.        *  This function is not concerned about whether the insertion took place,
  574.        *  and thus does not return a boolean like the single-argument emplace()
  575.        *  does.
  576.        *  Note that the first parameter is only a hint and can potentially
  577.        *  improve the performance of the insertion process. A bad hint would
  578.        *  cause no gains in efficiency.
  579.        *
  580.        *  See
  581.        *  https://gcc.gnu.org/onlinedocs/libstdc++/manual/associative.html#containers.associative.insert_hints
  582.        *  for more on @a hinting.
  583.        *
  584.        *  Insertion requires logarithmic time (if the hint is not taken).
  585.        */
  586.       template<typename... _Args>
  587.         iterator
  588.         emplace_hint(const_iterator __pos, _Args&&... __args)
  589.         {
  590.           return _M_t._M_emplace_hint_unique(__pos,
  591.                                              std::forward<_Args>(__args)...);
  592.         }
  593. #endif
  594.  
  595.       /**
  596.        *  @brief Attempts to insert a std::pair into the %map.
  597.  
  598.        *  @param __x Pair to be inserted (see std::make_pair for easy
  599.        *             creation of pairs).
  600.        *
  601.        *  @return  A pair, of which the first element is an iterator that
  602.        *           points to the possibly inserted pair, and the second is
  603.        *           a bool that is true if the pair was actually inserted.
  604.        *
  605.        *  This function attempts to insert a (key, value) %pair into the %map.
  606.        *  A %map relies on unique keys and thus a %pair is only inserted if its
  607.        *  first element (the key) is not already present in the %map.
  608.        *
  609.        *  Insertion requires logarithmic time.
  610.        */
  611.       std::pair<iterator, bool>
  612.       insert(const value_type& __x)
  613.       { return _M_t._M_insert_unique(__x); }
  614.  
  615. #if __cplusplus >= 201103L
  616.       template<typename _Pair, typename = typename
  617.                std::enable_if<std::is_constructible<value_type,
  618.                                                     _Pair&&>::value>::type>
  619.         std::pair<iterator, bool>
  620.         insert(_Pair&& __x)
  621.         { return _M_t._M_insert_unique(std::forward<_Pair>(__x)); }
  622. #endif
  623.  
  624. #if __cplusplus >= 201103L
  625.       /**
  626.        *  @brief Attempts to insert a list of std::pairs into the %map.
  627.        *  @param  __list  A std::initializer_list<value_type> of pairs to be
  628.        *                  inserted.
  629.        *
  630.        *  Complexity similar to that of the range constructor.
  631.        */
  632.       void
  633.       insert(std::initializer_list<value_type> __list)
  634.       { insert(__list.begin(), __list.end()); }
  635. #endif
  636.  
  637.       /**
  638.        *  @brief Attempts to insert a std::pair into the %map.
  639.        *  @param  __position  An iterator that serves as a hint as to where the
  640.        *                    pair should be inserted.
  641.        *  @param  __x  Pair to be inserted (see std::make_pair for easy creation
  642.        *               of pairs).
  643.        *  @return An iterator that points to the element with key of
  644.        *           @a __x (may or may not be the %pair passed in).
  645.        *
  646.  
  647.        *  This function is not concerned about whether the insertion
  648.        *  took place, and thus does not return a boolean like the
  649.        *  single-argument insert() does.  Note that the first
  650.        *  parameter is only a hint and can potentially improve the
  651.        *  performance of the insertion process.  A bad hint would
  652.        *  cause no gains in efficiency.
  653.        *
  654.        *  See
  655.        *  https://gcc.gnu.org/onlinedocs/libstdc++/manual/associative.html#containers.associative.insert_hints
  656.        *  for more on @a hinting.
  657.        *
  658.        *  Insertion requires logarithmic time (if the hint is not taken).
  659.        */
  660.       iterator
  661. #if __cplusplus >= 201103L
  662.       insert(const_iterator __position, const value_type& __x)
  663. #else
  664.       insert(iterator __position, const value_type& __x)
  665. #endif
  666.       { return _M_t._M_insert_unique_(__position, __x); }
  667.  
  668. #if __cplusplus >= 201103L
  669.       template<typename _Pair, typename = typename
  670.                std::enable_if<std::is_constructible<value_type,
  671.                                                     _Pair&&>::value>::type>
  672.         iterator
  673.         insert(const_iterator __position, _Pair&& __x)
  674.         { return _M_t._M_insert_unique_(__position,
  675.                                         std::forward<_Pair>(__x)); }
  676. #endif
  677.  
  678.       /**
  679.        *  @brief Template function that attempts to insert a range of elements.
  680.        *  @param  __first  Iterator pointing to the start of the range to be
  681.        *                   inserted.
  682.        *  @param  __last  Iterator pointing to the end of the range.
  683.        *
  684.        *  Complexity similar to that of the range constructor.
  685.        */
  686.       template<typename _InputIterator>
  687.         void
  688.         insert(_InputIterator __first, _InputIterator __last)
  689.         { _M_t._M_insert_unique(__first, __last); }
  690.  
  691. #if __cplusplus >= 201103L
  692.       // _GLIBCXX_RESOLVE_LIB_DEFECTS
  693.       // DR 130. Associative erase should return an iterator.
  694.       /**
  695.        *  @brief Erases an element from a %map.
  696.        *  @param  __position  An iterator pointing to the element to be erased.
  697.        *  @return An iterator pointing to the element immediately following
  698.        *          @a position prior to the element being erased. If no such
  699.        *          element exists, end() is returned.
  700.        *
  701.        *  This function erases an element, pointed to by the given
  702.        *  iterator, from a %map.  Note that this function only erases
  703.        *  the element, and that if the element is itself a pointer,
  704.        *  the pointed-to memory is not touched in any way.  Managing
  705.        *  the pointer is the user's responsibility.
  706.        */
  707.       iterator
  708.       erase(const_iterator __position)
  709.       { return _M_t.erase(__position); }
  710.  
  711.       // LWG 2059
  712.       _GLIBCXX_ABI_TAG_CXX11
  713.       iterator
  714.       erase(iterator __position)
  715.       { return _M_t.erase(__position); }
  716. #else
  717.       /**
  718.        *  @brief Erases an element from a %map.
  719.        *  @param  __position  An iterator pointing to the element to be erased.
  720.        *
  721.        *  This function erases an element, pointed to by the given
  722.        *  iterator, from a %map.  Note that this function only erases
  723.        *  the element, and that if the element is itself a pointer,
  724.        *  the pointed-to memory is not touched in any way.  Managing
  725.        *  the pointer is the user's responsibility.
  726.        */
  727.       void
  728.       erase(iterator __position)
  729.       { _M_t.erase(__position); }
  730. #endif
  731.  
  732.       /**
  733.        *  @brief Erases elements according to the provided key.
  734.        *  @param  __x  Key of element to be erased.
  735.        *  @return  The number of elements erased.
  736.        *
  737.        *  This function erases all the elements located by the given key from
  738.        *  a %map.
  739.        *  Note that this function only erases the element, and that if
  740.        *  the element is itself a pointer, the pointed-to memory is not touched
  741.        *  in any way.  Managing the pointer is the user's responsibility.
  742.        */
  743.       size_type
  744.       erase(const key_type& __x)
  745.       { return _M_t.erase(__x); }
  746.  
  747. #if __cplusplus >= 201103L
  748.       // _GLIBCXX_RESOLVE_LIB_DEFECTS
  749.       // DR 130. Associative erase should return an iterator.
  750.       /**
  751.        *  @brief Erases a [first,last) range of elements from a %map.
  752.        *  @param  __first  Iterator pointing to the start of the range to be
  753.        *                   erased.
  754.        *  @param __last Iterator pointing to the end of the range to
  755.        *                be erased.
  756.        *  @return The iterator @a __last.
  757.        *
  758.        *  This function erases a sequence of elements from a %map.
  759.        *  Note that this function only erases the element, and that if
  760.        *  the element is itself a pointer, the pointed-to memory is not touched
  761.        *  in any way.  Managing the pointer is the user's responsibility.
  762.        */
  763.       iterator
  764.       erase(const_iterator __first, const_iterator __last)
  765.       { return _M_t.erase(__first, __last); }
  766. #else
  767.       /**
  768.        *  @brief Erases a [__first,__last) range of elements from a %map.
  769.        *  @param  __first  Iterator pointing to the start of the range to be
  770.        *                   erased.
  771.        *  @param __last Iterator pointing to the end of the range to
  772.        *                be erased.
  773.        *
  774.        *  This function erases a sequence of elements from a %map.
  775.        *  Note that this function only erases the element, and that if
  776.        *  the element is itself a pointer, the pointed-to memory is not touched
  777.        *  in any way.  Managing the pointer is the user's responsibility.
  778.        */
  779.       void
  780.       erase(iterator __first, iterator __last)
  781.       { _M_t.erase(__first, __last); }
  782. #endif
  783.  
  784.       /**
  785.        *  @brief  Swaps data with another %map.
  786.        *  @param  __x  A %map of the same element and allocator types.
  787.        *
  788.        *  This exchanges the elements between two maps in constant
  789.        *  time.  (It is only swapping a pointer, an integer, and an
  790.        *  instance of the @c Compare type (which itself is often
  791.        *  stateless and empty), so it should be quite fast.)  Note
  792.        *  that the global std::swap() function is specialized such
  793.        *  that std::swap(m1,m2) will feed to this function.
  794.        */
  795.       void
  796.       swap(map& __x)
  797. #if __cplusplus >= 201103L
  798.       noexcept(_Alloc_traits::_S_nothrow_swap())
  799. #endif
  800.       { _M_t.swap(__x._M_t); }
  801.  
  802.       /**
  803.        *  Erases all elements in a %map.  Note that this function only
  804.        *  erases the elements, and that if the elements themselves are
  805.        *  pointers, the pointed-to memory is not touched in any way.
  806.        *  Managing the pointer is the user's responsibility.
  807.        */
  808.       void
  809.       clear() _GLIBCXX_NOEXCEPT
  810.       { _M_t.clear(); }
  811.  
  812.       // observers
  813.       /**
  814.        *  Returns the key comparison object out of which the %map was
  815.        *  constructed.
  816.        */
  817.       key_compare
  818.       key_comp() const
  819.       { return _M_t.key_comp(); }
  820.  
  821.       /**
  822.        *  Returns a value comparison object, built from the key comparison
  823.        *  object out of which the %map was constructed.
  824.        */
  825.       value_compare
  826.       value_comp() const
  827.       { return value_compare(_M_t.key_comp()); }
  828.  
  829.       // [23.3.1.3] map operations
  830.  
  831.       //@{
  832.       /**
  833.        *  @brief Tries to locate an element in a %map.
  834.        *  @param  __x  Key of (key, value) %pair to be located.
  835.        *  @return  Iterator pointing to sought-after element, or end() if not
  836.        *           found.
  837.        *
  838.        *  This function takes a key and tries to locate the element with which
  839.        *  the key matches.  If successful the function returns an iterator
  840.        *  pointing to the sought after %pair.  If unsuccessful it returns the
  841.        *  past-the-end ( @c end() ) iterator.
  842.        */
  843.  
  844.       iterator
  845.       find(const key_type& __x)
  846.       { return _M_t.find(__x); }
  847.  
  848. #if __cplusplus > 201103L
  849.       template<typename _Kt>
  850.         auto
  851.         find(const _Kt& __x) -> decltype(_M_t._M_find_tr(__x))
  852.         { return _M_t._M_find_tr(__x); }
  853. #endif
  854.       //@}
  855.  
  856.       //@{
  857.       /**
  858.        *  @brief Tries to locate an element in a %map.
  859.        *  @param  __x  Key of (key, value) %pair to be located.
  860.        *  @return  Read-only (constant) iterator pointing to sought-after
  861.        *           element, or end() if not found.
  862.        *
  863.        *  This function takes a key and tries to locate the element with which
  864.        *  the key matches.  If successful the function returns a constant
  865.        *  iterator pointing to the sought after %pair. If unsuccessful it
  866.        *  returns the past-the-end ( @c end() ) iterator.
  867.        */
  868.  
  869.       const_iterator
  870.       find(const key_type& __x) const
  871.       { return _M_t.find(__x); }
  872.  
  873. #if __cplusplus > 201103L
  874.       template<typename _Kt>
  875.         auto
  876.         find(const _Kt& __x) const -> decltype(_M_t._M_find_tr(__x))
  877.         { return _M_t._M_find_tr(__x); }
  878. #endif
  879.       //@}
  880.  
  881.       //@{
  882.       /**
  883.        *  @brief  Finds the number of elements with given key.
  884.        *  @param  __x  Key of (key, value) pairs to be located.
  885.        *  @return  Number of elements with specified key.
  886.        *
  887.        *  This function only makes sense for multimaps; for map the result will
  888.        *  either be 0 (not present) or 1 (present).
  889.        */
  890.       size_type
  891.       count(const key_type& __x) const
  892.       { return _M_t.find(__x) == _M_t.end() ? 0 : 1; }
  893.  
  894. #if __cplusplus > 201103L
  895.       template<typename _Kt>
  896.         auto
  897.         count(const _Kt& __x) const -> decltype(_M_t._M_count_tr(__x))
  898.         { return _M_t._M_find_tr(__x) == _M_t.end() ? 0 : 1; }
  899. #endif
  900.       //@}
  901.  
  902.       //@{
  903.       /**
  904.        *  @brief Finds the beginning of a subsequence matching given key.
  905.        *  @param  __x  Key of (key, value) pair to be located.
  906.        *  @return  Iterator pointing to first element equal to or greater
  907.        *           than key, or end().
  908.        *
  909.        *  This function returns the first element of a subsequence of elements
  910.        *  that matches the given key.  If unsuccessful it returns an iterator
  911.        *  pointing to the first element that has a greater value than given key
  912.        *  or end() if no such element exists.
  913.        */
  914.       iterator
  915.       lower_bound(const key_type& __x)
  916.       { return _M_t.lower_bound(__x); }
  917.  
  918. #if __cplusplus > 201103L
  919.       template<typename _Kt>
  920.         auto
  921.         lower_bound(const _Kt& __x)
  922.         -> decltype(_M_t._M_lower_bound_tr(__x))
  923.         { return _M_t._M_lower_bound_tr(__x); }
  924. #endif
  925.       //@}
  926.  
  927.       //@{
  928.       /**
  929.        *  @brief Finds the beginning of a subsequence matching given key.
  930.        *  @param  __x  Key of (key, value) pair to be located.
  931.        *  @return  Read-only (constant) iterator pointing to first element
  932.        *           equal to or greater than key, or end().
  933.        *
  934.        *  This function returns the first element of a subsequence of elements
  935.        *  that matches the given key.  If unsuccessful it returns an iterator
  936.        *  pointing to the first element that has a greater value than given key
  937.        *  or end() if no such element exists.
  938.        */
  939.       const_iterator
  940.       lower_bound(const key_type& __x) const
  941.       { return _M_t.lower_bound(__x); }
  942.  
  943. #if __cplusplus > 201103L
  944.       template<typename _Kt>
  945.         auto
  946.         lower_bound(const _Kt& __x) const
  947.         -> decltype(_M_t._M_lower_bound_tr(__x))
  948.         { return _M_t._M_lower_bound_tr(__x); }
  949. #endif
  950.       //@}
  951.  
  952.       //@{
  953.       /**
  954.        *  @brief Finds the end of a subsequence matching given key.
  955.        *  @param  __x  Key of (key, value) pair to be located.
  956.        *  @return Iterator pointing to the first element
  957.        *          greater than key, or end().
  958.        */
  959.       iterator
  960.       upper_bound(const key_type& __x)
  961.       { return _M_t.upper_bound(__x); }
  962.  
  963. #if __cplusplus > 201103L
  964.       template<typename _Kt>
  965.         auto
  966.         upper_bound(const _Kt& __x)
  967.         -> decltype(_M_t._M_upper_bound_tr(__x))
  968.         { return _M_t._M_upper_bound_tr(__x); }
  969. #endif
  970.       //@}
  971.  
  972.       //@{
  973.       /**
  974.        *  @brief Finds the end of a subsequence matching given key.
  975.        *  @param  __x  Key of (key, value) pair to be located.
  976.        *  @return  Read-only (constant) iterator pointing to first iterator
  977.        *           greater than key, or end().
  978.        */
  979.       const_iterator
  980.       upper_bound(const key_type& __x) const
  981.       { return _M_t.upper_bound(__x); }
  982.  
  983. #if __cplusplus > 201103L
  984.       template<typename _Kt>
  985.         auto
  986.         upper_bound(const _Kt& __x) const
  987.         -> decltype(_M_t._M_upper_bound_tr(__x))
  988.         { return _M_t._M_upper_bound_tr(__x); }
  989. #endif
  990.       //@}
  991.  
  992.       //@{
  993.       /**
  994.        *  @brief Finds a subsequence matching given key.
  995.        *  @param  __x  Key of (key, value) pairs to be located.
  996.        *  @return  Pair of iterators that possibly points to the subsequence
  997.        *           matching given key.
  998.        *
  999.        *  This function is equivalent to
  1000.        *  @code
  1001.        *    std::make_pair(c.lower_bound(val),
  1002.        *                   c.upper_bound(val))
  1003.        *  @endcode
  1004.        *  (but is faster than making the calls separately).
  1005.        *
  1006.        *  This function probably only makes sense for multimaps.
  1007.        */
  1008.       std::pair<iterator, iterator>
  1009.       equal_range(const key_type& __x)
  1010.       { return _M_t.equal_range(__x); }
  1011.  
  1012. #if __cplusplus > 201103L
  1013.       template<typename _Kt>
  1014.         auto
  1015.         equal_range(const _Kt& __x)
  1016.         -> decltype(_M_t._M_equal_range_tr(__x))
  1017.         { return _M_t._M_equal_range_tr(__x); }
  1018. #endif
  1019.       //@}
  1020.  
  1021.       //@{
  1022.       /**
  1023.        *  @brief Finds a subsequence matching given key.
  1024.        *  @param  __x  Key of (key, value) pairs to be located.
  1025.        *  @return  Pair of read-only (constant) iterators that possibly points
  1026.        *           to the subsequence matching given key.
  1027.        *
  1028.        *  This function is equivalent to
  1029.        *  @code
  1030.        *    std::make_pair(c.lower_bound(val),
  1031.        *                   c.upper_bound(val))
  1032.        *  @endcode
  1033.        *  (but is faster than making the calls separately).
  1034.        *
  1035.        *  This function probably only makes sense for multimaps.
  1036.        */
  1037.       std::pair<const_iterator, const_iterator>
  1038.       equal_range(const key_type& __x) const
  1039.       { return _M_t.equal_range(__x); }
  1040.  
  1041. #if __cplusplus > 201103L
  1042.       template<typename _Kt>
  1043.         auto
  1044.         equal_range(const _Kt& __x) const
  1045.         -> decltype(_M_t._M_equal_range_tr(__x))
  1046.         { return _M_t._M_equal_range_tr(__x); }
  1047. #endif
  1048.       //@}
  1049.  
  1050.       template<typename _K1, typename _T1, typename _C1, typename _A1>
  1051.         friend bool
  1052.         operator==(const map<_K1, _T1, _C1, _A1>&,
  1053.                    const map<_K1, _T1, _C1, _A1>&);
  1054.  
  1055.       template<typename _K1, typename _T1, typename _C1, typename _A1>
  1056.         friend bool
  1057.         operator<(const map<_K1, _T1, _C1, _A1>&,
  1058.                   const map<_K1, _T1, _C1, _A1>&);
  1059.     };
  1060.  
  1061.   /**
  1062.    *  @brief  Map equality comparison.
  1063.    *  @param  __x  A %map.
  1064.    *  @param  __y  A %map of the same type as @a x.
  1065.    *  @return  True iff the size and elements of the maps are equal.
  1066.    *
  1067.    *  This is an equivalence relation.  It is linear in the size of the
  1068.    *  maps.  Maps are considered equivalent if their sizes are equal,
  1069.    *  and if corresponding elements compare equal.
  1070.   */
  1071.   template<typename _Key, typename _Tp, typename _Compare, typename _Alloc>
  1072.     inline bool
  1073.     operator==(const map<_Key, _Tp, _Compare, _Alloc>& __x,
  1074.                const map<_Key, _Tp, _Compare, _Alloc>& __y)
  1075.     { return __x._M_t == __y._M_t; }
  1076.  
  1077.   /**
  1078.    *  @brief  Map ordering relation.
  1079.    *  @param  __x  A %map.
  1080.    *  @param  __y  A %map of the same type as @a x.
  1081.    *  @return  True iff @a x is lexicographically less than @a y.
  1082.    *
  1083.    *  This is a total ordering relation.  It is linear in the size of the
  1084.    *  maps.  The elements must be comparable with @c <.
  1085.    *
  1086.    *  See std::lexicographical_compare() for how the determination is made.
  1087.   */
  1088.   template<typename _Key, typename _Tp, typename _Compare, typename _Alloc>
  1089.     inline bool
  1090.     operator<(const map<_Key, _Tp, _Compare, _Alloc>& __x,
  1091.               const map<_Key, _Tp, _Compare, _Alloc>& __y)
  1092.     { return __x._M_t < __y._M_t; }
  1093.  
  1094.   /// Based on operator==
  1095.   template<typename _Key, typename _Tp, typename _Compare, typename _Alloc>
  1096.     inline bool
  1097.     operator!=(const map<_Key, _Tp, _Compare, _Alloc>& __x,
  1098.                const map<_Key, _Tp, _Compare, _Alloc>& __y)
  1099.     { return !(__x == __y); }
  1100.  
  1101.   /// Based on operator<
  1102.   template<typename _Key, typename _Tp, typename _Compare, typename _Alloc>
  1103.     inline bool
  1104.     operator>(const map<_Key, _Tp, _Compare, _Alloc>& __x,
  1105.               const map<_Key, _Tp, _Compare, _Alloc>& __y)
  1106.     { return __y < __x; }
  1107.  
  1108.   /// Based on operator<
  1109.   template<typename _Key, typename _Tp, typename _Compare, typename _Alloc>
  1110.     inline bool
  1111.     operator<=(const map<_Key, _Tp, _Compare, _Alloc>& __x,
  1112.                const map<_Key, _Tp, _Compare, _Alloc>& __y)
  1113.     { return !(__y < __x); }
  1114.  
  1115.   /// Based on operator<
  1116.   template<typename _Key, typename _Tp, typename _Compare, typename _Alloc>
  1117.     inline bool
  1118.     operator>=(const map<_Key, _Tp, _Compare, _Alloc>& __x,
  1119.                const map<_Key, _Tp, _Compare, _Alloc>& __y)
  1120.     { return !(__x < __y); }
  1121.  
  1122.   /// See std::map::swap().
  1123.   template<typename _Key, typename _Tp, typename _Compare, typename _Alloc>
  1124.     inline void
  1125.     swap(map<_Key, _Tp, _Compare, _Alloc>& __x,
  1126.          map<_Key, _Tp, _Compare, _Alloc>& __y)
  1127.     { __x.swap(__y); }
  1128.  
  1129. _GLIBCXX_END_NAMESPACE_CONTAINER
  1130. } // namespace std
  1131.  
  1132. #endif /* _STL_MAP_H */
  1133.