hash_namespace.h

/*    Copyright 2013 10gen Inc.
 *
 *    Licensed under the Apache License, Version 2.0 (the "License");
 *    you may not use this file except in compliance with the License.
 *    You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing, software
 *    distributed under the License is distributed on an "AS IS" BASIS,
 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *    See the License for the specific language governing permissions and
 *    limitations under the License.
 */

#pragma once

// We need to drag in a C++ header so we can examine __GXX_EXPERIMENTAL_CXX0X__ or
// _LIBCPP_VERSION meaningfully. The <new> header is pretty lightweight, mostly unavoidable,
// and almost certain to bring in the standard library configuration macros.
#include <new>

// NOTE(acm): Before gcc-4.7, __cplusplus is always defined to be 1, so we can't reliably
// detect C++11 support by exclusively checking the value of __cplusplus.  Additionaly, libc++,
// whether in C++11 or C++03 mode, doesn't use TR1 and drops things into std instead.
#if __cplusplus >= 201103L || defined(__GXX_EXPERIMENTAL_CXX0X__) || defined(_LIBCPP_VERSION)

#include <functional>

#define MONGO_HASH_NAMESPACE_START namespace std {
#define MONGO_HASH_NAMESPACE_END }
#define MONGO_HASH_NAMESPACE std

#elif defined(_MSC_VER) && _MSC_VER >= 1500

#if _MSC_VER >= 1600 /* Visual Studio 2010+ */

#include <functional>

#define MONGO_HASH_NAMESPACE_START namespace std {
#define MONGO_HASH_NAMESPACE_END }
#define MONGO_HASH_NAMESPACE std

#else /* Older Visual Studio */

#include <tr1/functional>

#define MONGO_HASH_NAMESPACE_START \
    namespace std {                \
    namespace tr1 {
#define MONGO_HASH_NAMESPACE_END \
    }                            \
    }
#define MONGO_HASH_NAMESPACE std::tr1

#endif

#elif defined(__GNUC__)

#include <tr1/functional>

#define MONGO_HASH_NAMESPACE_START \
    namespace std {                \
    namespace tr1 {
#define MONGO_HASH_NAMESPACE_END \
    }                            \
    }
#define MONGO_HASH_NAMESPACE std::tr1

#else
#error "Cannot determine namespace for 'hash'"
#endif