projectn.h

来自「C++ Standard Library, A Tutorial and Ref」· C头文件 代码 · 共 34 行

/*
 *
 * 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.
 *
 */

#ifndef PROJECTN_H
#define PROJECTN_H

#include <function.h>

template <class T, class U>
struct select1st : public unary_function<T, U> {
    const U& operator()(const T& x) const { return x.first; }
};

template <class T, class U>
struct ident : public unary_function<T, U> {
    const U& operator()(const T& x) const { return x; }
};

#endif