+// Pair implementation -*- C++ -*-
+
+// Copyright (C) 2001, 2004 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
* 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.
+/** @file stl_pair.h
+ * This is an internal header file, included by other library headers.
+ * You should not attempt to use it directly.
*/
-#ifndef __SGI_STL_INTERNAL_PAIR_H
-#define __SGI_STL_INTERNAL_PAIR_H
+#ifndef _PAIR_H
+#define _PAIR_H 1
namespace std
{
-template <class _T1, class _T2>
-struct pair {
- typedef _T1 first_type;
- typedef _T2 second_type;
-
- _T1 first;
- _T2 second;
- pair() : first(_T1()), second(_T2()) {}
- pair(const _T1& __a, const _T2& __b) : first(__a), second(__b) {}
-
- template <class _U1, class _U2>
- pair(const pair<_U1, _U2>& __p) : first(__p.first), second(__p.second) {}
-};
-
-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);
-}
-
-template <class _T1, class _T2>
-inline bool operator!=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y) {
- return !(__x == __y);
-}
-
-template <class _T1, class _T2>
-inline bool operator>(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y) {
- return __y < __x;
-}
-
-template <class _T1, class _T2>
-inline bool operator<=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y) {
- return !(__y < __x);
-}
-
-template <class _T1, class _T2>
-inline bool operator>=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y) {
- return !(__x < __y);
-}
-
-template <class _T1, class _T2>
-#ifdef _GLIBCPP_RESOLVE_LIB_DEFECTS
-//181. make_pair() unintended behavior
-inline pair<_T1, _T2> make_pair(const _T1 __x, const _T2 __y)
-#else
-inline pair<_T1, _T2> make_pair(const _T1& __x, const _T2& __y)
-#endif
-{
- return pair<_T1, _T2>(__x, __y);
-}
+ /// pair holds two objects of arbitrary type.
+ template <class _T1, class _T2>
+ struct pair
+ {
+ typedef _T1 first_type; ///< @c first_type is the first bound type
+ typedef _T2 second_type; ///< @c second_type is the second bound type
+
+ _T1 first; ///< @c first is a copy of the first object
+ _T2 second; ///< @c second is a copy of the second object
+
+ // _GLIBCXX_RESOLVE_LIB_DEFECTS
+ // 265. std::pair::pair() effects overly restrictive
+ /** The default constructor creates @c first and @c second using their
+ * respective default constructors. */
+ pair()
+ : first(), second() {}
+
+ /** Two objects may be passed to a @c pair constructor to be copied. */
+ pair(const _T1& __a, const _T2& __b)
+ : first(__a), second(__b) {}
+
+ /** There is also a templated copy ctor for the @c pair class itself. */
+ template <class _U1, class _U2>
+ pair(const pair<_U1, _U2>& __p)
+ : first(__p.first), second(__p.second) {}
+ };
+
+ /// Two pairs of the same type are equal iff their members are equal.
+ 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; }
+
+ /// <http://gcc.gnu.org/onlinedocs/libstdc++/20_util/howto.html#pairlt>
+ 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); }
+
+ /// Uses @c operator== to find the result.
+ template <class _T1, class _T2>
+ inline bool
+ operator!=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
+ { return !(__x == __y); }
+
+ /// Uses @c operator< to find the result.
+ template <class _T1, class _T2>
+ inline bool
+ operator>(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
+ { return __y < __x; }
+
+ /// Uses @c operator< to find the result.
+ template <class _T1, class _T2>
+ inline bool
+ operator<=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
+ { return !(__y < __x); }
+
+ /// Uses @c operator< to find the result.
+ template <class _T1, class _T2>
+ inline bool
+ operator>=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
+ { return !(__x < __y); }
+
+ /**
+ * @brief A convenience wrapper for creating a pair from two objects.
+ * @param x The first object.
+ * @param y The second object.
+ * @return A newly-constructed pair<> object of the appropriate type.
+ *
+ * The standard requires that the objects be passed by reference-to-const,
+ * but LWG issue #181 says they should be passed by const value. We follow
+ * the LWG by default.
+ */
+ template <class _T1, class _T2>
+
+ // _GLIBCXX_RESOLVE_LIB_DEFECTS
+ // 181. make_pair() unintended behavior
+ inline pair<_T1, _T2>
+ make_pair(_T1 __x, _T2 __y)
+ { return pair<_T1, _T2>(__x, __y); }
} // namespace std
-#endif /* __SGI_STL_INTERNAL_PAIR_H */
+#endif /* _PAIR_H */
// Local Variables:
// mode:C++
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