stl_map.h

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// Map implementation -*- C++ -*-

// Copyright (C) 2001, 2002 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 2, or (at your option)
// any later version.

// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License along
// with this library; see the file COPYING.  If not, write to the Free
// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
// USA.

// As a special exception, you may use this file as part of a free software
// library without restriction.  Specifically, if other files instantiate
// templates or use macros or inline functions from this file, or you compile
// this file and link it with other files to produce an executable, this
// file does not by itself cause the resulting executable to be covered by
// the GNU General Public License.  This exception does not however
// invalidate any other reasons why the executable file might be covered by
// the GNU General Public License.

/*
 *
 * Copyright (c) 1994
 * Hewlett-Packard Company
 *
 * Permission to use, copy, modify, distribute and sell this software
 * and its documentation for any purpose is hereby granted without fee,
 * provided that the above copyright notice appear in all copies and
 * that both that copyright notice and this permission notice appear
 * in supporting documentation.  Hewlett-Packard Company makes no
 * representations about the suitability of this software for any
 * purpose.  It is provided "as is" without express or implied warranty.
 *
 *
 * Copyright (c) 1996,1997
 * Silicon Graphics Computer Systems, Inc.
 *
 * Permission to use, copy, modify, distribute and sell this software
 * and its documentation for any purpose is hereby granted without fee,
 * provided that the above copyright notice appear in all copies and
 * that both that copyright notice and this permission notice appear
 * in supporting documentation.  Silicon Graphics makes no
 * representations about the suitability of this software for any
 * purpose.  It is provided "as is" without express or implied warranty.
 */

/** @file stl_map.h
 *  This is an internal header file, included by other library headers.
 *  You should not attempt to use it directly.
 */

#ifndef __GLIBCPP_INTERNAL_MAP_H
#define __GLIBCPP_INTERNAL_MAP_H

#include <bits/concept_check.h>

namespace std
{
  /**
   *  @brief A standard container made up of (key,value) pairs, which can be
   *  retrieved based on a key, in logarithmic time.
   *
   *  @ingroup Containers
   *  @ingroup Assoc_containers
   *
   *  Meets the requirements of a <a href="tables.html#65">container</a>, a
   *  <a href="tables.html#66">reversible container</a>, and an
   *  <a href="tables.html#69">associative container</a> (using unique keys).
   *  For a @c map<Key,T> the key_type is Key, the mapped_type is T, and the
   *  value_type is std::pair<const Key,T>.
   *
   *  Maps support bidirectional iterators.
   *
   *  @if maint
   *  The private tree data is declared exactly the same way for map and
   *  multimap; the distinction is made entirely in how the tree functions are
   *  called (*_unique versus *_equal, same as the standard).
   *  @endif
  */
  template <typename _Key, typename _Tp, typename _Compare = less<_Key>,
            typename _Alloc = allocator<pair<const _Key, _Tp> > >
    class map
  {
    // concept requirements
    __glibcpp_class_requires(_Tp, _SGIAssignableConcept)
    __glibcpp_class_requires4(_Compare, bool, _Key, _Key, _BinaryFunctionConcept)
  
  public:
    typedef _Key                                          key_type;
    typedef _Tp                                           mapped_type;
    typedef pair<const _Key, _Tp>                         value_type;
    typedef _Compare                                      key_compare;
  
    class value_compare
      : public binary_function<value_type, value_type, bool>
      {
        friend class map<_Key,_Tp,_Compare,_Alloc>;
      protected:
        _Compare comp;
        value_compare(_Compare __c) : comp(__c) {}
      public:
        bool operator()(const value_type& __x, const value_type& __y) const
        { return comp(__x.first, __y.first); }
      };
  
  private:
    /// @if maint  This turns a red-black tree into a [multi]map.  @endif
    typedef _Rb_tree<key_type, value_type,
                     _Select1st<value_type>, key_compare, _Alloc> _Rep_type;
    /// @if maint  The actual tree structure.  @endif
    _Rep_type _M_t;
  
  public:
    // many of these are specified differently in ISO, but the following are
    // "functionally equivalent"
    typedef typename _Rep_type::allocator_type            allocator_type;
    typedef typename _Rep_type::reference                 reference;
    typedef typename _Rep_type::const_reference           const_reference;
    typedef typename _Rep_type::iterator                  iterator;
    typedef typename _Rep_type::const_iterator            const_iterator;
    typedef typename _Rep_type::size_type                 size_type;
    typedef typename _Rep_type::difference_type           difference_type;
    typedef typename _Rep_type::pointer                   pointer;
    typedef typename _Rep_type::const_pointer             const_pointer;
    typedef typename _Rep_type::reverse_iterator          reverse_iterator;
    typedef typename _Rep_type::const_reverse_iterator    const_reverse_iterator;
  
  
    // [23.3.1.1] construct/copy/destroy
    // (get_allocator() is normally listed in this section, but seems to have
    // been accidentally omitted in the printed standard)
    /**
     *  @brief  Default constructor creates no elements.
    */
    map() : _M_t(_Compare(), allocator_type()) { }
  
    // for some reason this was made a separate function
    /**
     *  @brief  Default constructor creates no elements.
    */
    explicit
    map(const _Compare& __comp, const allocator_type& __a = allocator_type())
      : _M_t(__comp, __a) { }
  
    /**
     *  @brief  Map copy constructor.
     *  @param  x  A %map of identical element and allocator types.
     *
     *  The newly-created %map uses a copy of the allocation object used
     *  by @a x.
    */
    map(const map& __x)
      : _M_t(__x._M_t) { }
  
    /**
     *  @brief  Builds a %map from a range.
     *  @param  first  An input iterator.
     *  @param  last  An input iterator.
     *
     *  Create a %map consisting of copies of the elements from [first,last).
     *  This is linear in N if the range is already sorted, and NlogN
     *  otherwise (where N is distance(first,last)).
    */
    template <typename _InputIterator>
      map(_InputIterator __first, _InputIterator __last)
      : _M_t(_Compare(), allocator_type())
      { _M_t.insert_unique(__first, __last); }
  
    /**
     *  @brief  Builds a %map from a range.
     *  @param  first  An input iterator.
     *  @param  last  An input iterator.
     *  @param  comp  A comparison functor.
     *  @param  a  An allocator object.
     *
     *  Create a %map consisting of copies of the elements from [first,last).
     *  This is linear in N if the range is already sorted, and NlogN
     *  otherwise (where N is distance(first,last)).
    */
    template <typename _InputIterator>
      map(_InputIterator __first, _InputIterator __last,
          const _Compare& __comp, const allocator_type& __a = allocator_type())
      : _M_t(__comp, __a)
      { _M_t.insert_unique(__first, __last); }
  
    // FIXME There is no dtor declared, but we should have something generated
    // by Doxygen.  I don't know what tags to add to this paragraph to make
    // that happen:
    /**
     *  The dtor only erases the elements, and note that if the elements
     *  themselves are pointers, the pointed-to memory is not touched in any
     *  way.  Managing the pointer is the user's responsibilty.
    */
  
    /**
     *  @brief  Map assignment operator.
     *  @param  x  A %map of identical element and allocator types.
     *
     *  All the elements of @a x are copied, but unlike the copy constructor,
     *  the allocator object is not copied.
    */
    map&
    operator=(const map& __x)
    {
      _M_t = __x._M_t;
      return *this;
    }
  
    /// Get a copy of the memory allocation object.
    allocator_type
    get_allocator() const { return _M_t.get_allocator(); }
  
    // iterators
    /**
     *  Returns a read/write iterator that points to the first pair in the %map.
     *  Iteration is done in ascending order according to the keys.
    */
    iterator
    begin() { return _M_t.begin(); }
  
    /**
     *  Returns a read-only (constant) iterator that points to the first pair
     *  in the %map.  Iteration is done in ascending order according to the
     *  keys.
    */
    const_iterator
    begin() const { return _M_t.begin(); }
  
    /**
     *  Returns a read/write iterator that points one past the last pair in the
     *  %map.  Iteration is done in ascending order according to the keys.
    */
    iterator
    end() { return _M_t.end(); }
  
    /**
     *  Returns a read-only (constant) iterator that points one past the last
     *  pair in the %map.  Iteration is done in ascending order according to the
     *  keys.
    */
    const_iterator
    end() const { return _M_t.end(); }
  
    /**
     *  Returns a read/write reverse iterator that points to the last pair in
     *  the %map.  Iteration is done in descending order according to the keys.
    */
    reverse_iterator
    rbegin() { return _M_t.rbegin(); }
  
    /**
     *  Returns a read-only (constant) reverse iterator that points to the last
     *  pair in the %map.  Iteration is done in descending order according to
     *  the keys.
    */
    const_reverse_iterator
    rbegin() const { return _M_t.rbegin(); }
  
    /**
     *  Returns a read/write reverse iterator that points to one before the
     *  first pair in the %map.  Iteration is done in descending order according
     *  to the keys.
    */
    reverse_iterator
    rend() { return _M_t.rend(); }
  
    /**
     *  Returns a read-only (constant) reverse iterator that points to one
     *  before the first pair in the %map.  Iteration is done in descending
     *  order according to the keys.
    */
    const_reverse_iterator
    rend() const { return _M_t.rend(); }
  
    // capacity
    /** Returns true if the %map is empty.  (Thus begin() would equal end().) */
    bool
    empty() const { return _M_t.empty(); }
  
    /** Returns the size of the %map.  */
    size_type
    size() const { return _M_t.size(); }
  
    /** Returns the maximum size of the %map.  */
    size_type
    max_size() const { return _M_t.max_size(); }
  
    // [23.3.1.2] element access
    /**
     *  @brief  Subscript ( @c [] ) access to %map data.
     *  @param  k  The key for which data should be retrieved.
     *  @return  A reference to the data of the (key,data) %pair.
     *
     *  Allows for easy lookup with the subscript ( @c [] ) operator.  Returns
     *  data associated with the key specified in subscript.  If the key does
     *  not exist, a pair with that key is created using default values, which
     *  is then returned.
     *
     *  Lookup requires logarithmic time.
    */
    mapped_type&
    operator[](const key_type& __k)
    {
      // concept requirements
      __glibcpp_function_requires(_DefaultConstructibleConcept<mapped_type>)
  
      iterator __i = lower_bound(__k);
      // __i->first is greater than or equivalent to __k.
      if (__i == end() || key_comp()(__k, (*__i).first))
        __i = insert(__i, value_type(__k, mapped_type()));
      return (*__i).second;
    }
  
    // modifiers
    /**
     *  @brief Attempts to insert a std::pair into the %map.
     *  @param  x  Pair to be inserted (see std::make_pair for easy creation of
     *             pairs).
     *  @return  A pair, of which the first element is an iterator that points
     *           to the possibly inserted pair, and the second is a bool that
     *           is true if the pair was actually inserted.
     *