簡介

queue是一種先入先出（FIFO）的資料結構，它有兩個出口，允許從底端加入元素，從頂端移除元素。 STL底層預設基于deque容器實作，可在建立是更改list：

queue< string, list<string> > str_queue; // 由list實作的queue

priority_queue是擁有權值的queue，其内部元素不是按照添加的順序排列，而是按照權值排列（權值預設為元素值），權值高的拍在前邊。 STL底層預設基于vector容器實作，可以在建立是更改為deque：

queue< string, list<string> > str_queue; // 由list實作的queue

特性

queue先入先出（FIFO）。 queue由于需要支援pop_front，是以不能有vector容器實作。 queue不提供周遊功能，沒有疊代器。 priority_queue權值高先出。 priority_queue支援随機通路功能，是以建立在vector或deque容器上。

常用操作

q.empty()	如果隊列為空，則傳回 true，否則傳回 false
q.size()	傳回隊列中元素的個數
q.pop()	删除隊首元素，但不傳回其值
q.front()	傳回隊首元素的值，但不删除該元素該操作隻适用于隊列
q.back()	傳回隊尾元素的值，但不删除該元素該操作隻适用于隊列
q.top()	傳回具有最高優先級的元素值，但不删除該素該操作隻适用于優先級隊列
q.push(item)	對于 queue，在隊尾壓入一個新元素，對于 priority_quue，在基于優先級的适當位置插入新元素

源碼（STL3.3）

/*
 *
 * 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.
 */

/* NOTE: This is an internal header file, included by other STL headers.
 *   You should not attempt to use it directly.
 */

#ifndef __SGI_STL_INTERNAL_QUEUE_H
#define __SGI_STL_INTERNAL_QUEUE_H

#include <sequence_concepts.h>

__STL_BEGIN_NAMESPACE

// Forward declarations of operators < and ==, needed for friend declaration.

template <class _Tp, 
          class _Sequence __STL_DEPENDENT_DEFAULT_TMPL(deque<_Tp>) >
class queue;

template <class _Tp, class _Seq>
inline bool operator==(const queue<_Tp, _Seq>&, const queue<_Tp, _Seq>&);

template <class _Tp, class _Seq>
inline bool operator<(const queue<_Tp, _Seq>&, const queue<_Tp, _Seq>&);


template <class _Tp, class _Sequence>
class queue {

  // requirements:

  __STL_CLASS_REQUIRES(_Tp, _Assignable);
  __STL_CLASS_REQUIRES(_Sequence, _FrontInsertionSequence);
  __STL_CLASS_REQUIRES(_Sequence, _BackInsertionSequence);
  typedef typename _Sequence::value_type _Sequence_value_type;
  __STL_CLASS_REQUIRES_SAME_TYPE(_Tp, _Sequence_value_type);


#ifdef __STL_MEMBER_TEMPLATES 
  template <class _Tp1, class _Seq1>
  friend bool operator== (const queue<_Tp1, _Seq1>&,
                          const queue<_Tp1, _Seq1>&);
  template <class _Tp1, class _Seq1>
  friend bool operator< (const queue<_Tp1, _Seq1>&,
                         const queue<_Tp1, _Seq1>&);
#else /* __STL_MEMBER_TEMPLATES */
  friend bool __STD_QUALIFIER
  operator== __STL_NULL_TMPL_ARGS (const queue&, const queue&);
  friend bool __STD_QUALIFIER
  operator<  __STL_NULL_TMPL_ARGS (const queue&, const queue&);
#endif /* __STL_MEMBER_TEMPLATES */

public:
  typedef typename _Sequence::value_type      value_type;
  typedef typename _Sequence::size_type       size_type;
  typedef          _Sequence                  container_type;

  typedef typename _Sequence::reference       reference;
  typedef typename _Sequence::const_reference const_reference;
protected:
  _Sequence c;
public:
  queue() : c() {}
  explicit queue(const _Sequence& __c) : c(__c) {}

  bool empty() const { return c.empty(); }
  size_type size() const { return c.size(); }
  reference front() { return c.front(); }
  const_reference front() const { return c.front(); }
  reference back() { return c.back(); }
  const_reference back() const { return c.back(); }
  void push(const value_type& __x) { c.push_back(__x); }
  void pop() { c.pop_front(); }
};

template <class _Tp, class _Sequence>
bool 
operator==(const queue<_Tp, _Sequence>& __x, const queue<_Tp, _Sequence>& __y)
{
  return __x.c == __y.c;
}

template <class _Tp, class _Sequence>
bool
operator<(const queue<_Tp, _Sequence>& __x, const queue<_Tp, _Sequence>& __y)
{
  return __x.c < __y.c;
}

#ifdef __STL_FUNCTION_TMPL_PARTIAL_ORDER

template <class _Tp, class _Sequence>
bool
operator!=(const queue<_Tp, _Sequence>& __x, const queue<_Tp, _Sequence>& __y)
{
  return !(__x == __y);
}

template <class _Tp, class _Sequence>
bool 
operator>(const queue<_Tp, _Sequence>& __x, const queue<_Tp, _Sequence>& __y)
{
  return __y < __x;
}

template <class _Tp, class _Sequence>
bool 
operator<=(const queue<_Tp, _Sequence>& __x, const queue<_Tp, _Sequence>& __y)
{
  return !(__y < __x);
}

template <class _Tp, class _Sequence>
bool 
operator>=(const queue<_Tp, _Sequence>& __x, const queue<_Tp, _Sequence>& __y)
{
  return !(__x < __y);
}

#endif /* __STL_FUNCTION_TMPL_PARTIAL_ORDER */

template <class _Tp, 
          class _Sequence __STL_DEPENDENT_DEFAULT_TMPL(vector<_Tp>),
          class _Compare
          __STL_DEPENDENT_DEFAULT_TMPL(less<typename _Sequence::value_type>) >
class priority_queue {

  // requirements:

  __STL_CLASS_REQUIRES(_Tp, _Assignable);
  __STL_CLASS_REQUIRES(_Sequence, _Sequence);
  __STL_CLASS_REQUIRES(_Sequence, _RandomAccessContainer);
  typedef typename _Sequence::value_type _Sequence_value_type;
  __STL_CLASS_REQUIRES_SAME_TYPE(_Tp, _Sequence_value_type);
  __STL_CLASS_BINARY_FUNCTION_CHECK(_Compare, bool, _Tp, _Tp);

public:
  typedef typename _Sequence::value_type      value_type;
  typedef typename _Sequence::size_type       size_type;
  typedef          _Sequence                  container_type;

  typedef typename _Sequence::reference       reference;
  typedef typename _Sequence::const_reference const_reference;
protected:
  _Sequence c;
  _Compare comp;
public:
  priority_queue() : c() {}
  explicit priority_queue(const _Compare& __x) :  c(), comp(__x) {}
  priority_queue(const _Compare& __x, const _Sequence& __s) 
    : c(__s), comp(__x) 
    { make_heap(c.begin(), c.end(), comp); }

#ifdef __STL_MEMBER_TEMPLATES
  template <class _InputIterator>
  priority_queue(_InputIterator __first, _InputIterator __last) 
    : c(__first, __last) { make_heap(c.begin(), c.end(), comp); }

  template <class _InputIterator>
  priority_queue(_InputIterator __first, 
                 _InputIterator __last, const _Compare& __x)
    : c(__first, __last), comp(__x) 
    { make_heap(c.begin(), c.end(), comp); }

  template <class _InputIterator>
  priority_queue(_InputIterator __first, _InputIterator __last,
                 const _Compare& __x, const _Sequence& __s)
  : c(__s), comp(__x)
  { 
    c.insert(c.end(), __first, __last);
    make_heap(c.begin(), c.end(), comp);
  }

#else /* __STL_MEMBER_TEMPLATES */
  priority_queue(const value_type* __first, const value_type* __last) 
    : c(__first, __last) { make_heap(c.begin(), c.end(), comp); }

  priority_queue(const value_type* __first, const value_type* __last, 
                 const _Compare& __x) 
    : c(__first, __last), comp(__x)
    { make_heap(c.begin(), c.end(), comp); }

  priority_queue(const value_type* __first, const value_type* __last, 
                 const _Compare& __x, const _Sequence& __c)
    : c(__c), comp(__x) 
  { 
    c.insert(c.end(), __first, __last);
    make_heap(c.begin(), c.end(), comp);
  }
#endif /* __STL_MEMBER_TEMPLATES */

  bool empty() const { return c.empty(); }
  size_type size() const { return c.size(); }
  const_reference top() const { return c.front(); }
  void push(const value_type& __x) {
    __STL_TRY {
      c.push_back(__x); 
      push_heap(c.begin(), c.end(), comp);
    }
    __STL_UNWIND(c.clear());
  }
  void pop() {
    __STL_TRY {
      pop_heap(c.begin(), c.end(), comp);
      c.pop_back();
    }
    __STL_UNWIND(c.clear());
  }
};

// no equality is provided

__STL_END_NAMESPACE

#endif /* __SGI_STL_INTERNAL_QUEUE_H */

// Local Variables:
// mode:C++
// End:

STL學習--queue priority_queue簡介特性常用操作源碼（STL3.3）

簡介

特性

常用操作

源碼（STL3.3）

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