『STLソース剖析』---stl_pair.hノートを読む
pairはSTLのテンプレートタイプで、2つの要素を格納することができ、「対グループ」とも呼ばれます.mapではすでに使用されていますが、pairは実はstruct構造で、2つのpublicの要素が保存されており、いくつかの演算子が再ロードされており、メンバー関数はなく、ソースコードは簡単です.
G++ 2.91.57，cygnus\cygwin-b20\include\g++\stl_pair.h
/*
*
* 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_PAIR_H
#define __SGI_STL_INTERNAL_PAIR_H
__STL_BEGIN_NAMESPACE
template <class T1, class T2>
struct pair {
typedef T1 first_type;
typedef T2 second_type;
// ， struct public
T1 first; // ， public
T2 second; // ， public
//
// pair
pair() : first(T1()), second(T2()) {}
pair(const T1& a, const T2& b) : first(a), second(b) {}
#ifdef __STL_MEMBER_TEMPLATES
// pair pair， ， 。
template <class U1, class U2>
pair(const pair<U1, U2>& p) : first(p.first), second(p.second) {}
#endif
};
// pair ， 。
template <class T1, class T2>
inline bool operator==(const pair<T1, T2>& x, const pair<T1, T2>& y) {
return x.first == y.first && x.second == y.second;
}
template <class T1, class T2>
inline bool operator<(const pair<T1, T2>& x, const pair<T1, T2>& y) {
return x.first < y.first || (!(y.first < x.first) && x.second < y.second);
// x y ， ，x y
// x y ， x y。
}
// ， pair
template <class T1, class T2>
inline pair<T1, T2> make_pair(const T1& x, const T2& y) {
return pair<T1, T2>(x, y);
}
__STL_END_NAMESPACE
#endif /* __SGI_STL_INTERNAL_PAIR_H */
// Local Variables:
// mode:C++
// End: