1 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 // 5 6 // 7 // Deal with the differences between Microsoft and GNU implemenations 8 // of hash_map. Allows all platforms to use |base::hash_map| and 9 // |base::hash_set|. 10 // eg: 11 // base::hash_map<int> my_map; 12 // base::hash_set<int> my_set; 13 // 14 // NOTE: It is an explicit non-goal of this class to provide a generic hash 15 // function for pointers. If you want to hash a pointers to a particular class, 16 // please define the template specialization elsewhere (for example, in its 17 // header file) and keep it specific to just pointers to that class. This is 18 // because identity hashes are not desirable for all types that might show up 19 // in containers as pointers. 20 21 #ifndef BASE_HASH_TABLES_H_ 22 #define BASE_HASH_TABLES_H_ 23 #pragma once 24 25 #include "build/build_config.h" 26 27 #include "base/string16.h" 28 29 #if defined(COMPILER_MSVC) 30 #include <hash_map> 31 #include <hash_set> 32 namespace base { 33 using stdext::hash_map; 34 using stdext::hash_set; 35 } 36 #elif defined(COMPILER_GCC) 37 // This is a hack to disable the gcc 4.4 warning about hash_map and hash_set 38 // being deprecated. We can get rid of this when we upgrade to VS2008 and we 39 // can use <tr1/unordered_map> and <tr1/unordered_set>. 40 #ifdef __DEPRECATED 41 #define CHROME_OLD__DEPRECATED __DEPRECATED 42 #undef __DEPRECATED 43 #endif 44 45 #include <ext/hash_map> 46 #include <ext/hash_set> 47 #include <string> 48 49 #ifdef CHROME_OLD__DEPRECATED 50 #define __DEPRECATED CHROME_OLD__DEPRECATED 51 #undef CHROME_OLD__DEPRECATED 52 #endif 53 54 namespace base { 55 using __gnu_cxx::hash_map; 56 using __gnu_cxx::hash_set; 57 } // namespace base 58 59 namespace __gnu_cxx { 60 61 #ifndef ANDROID 62 // Already defined for android 63 64 // The GNU C++ library provides identity hash functions for many integral types, 65 // but not for |long long|. This hash function will truncate if |size_t| is 66 // narrower than |long long|. This is probably good enough for what we will 67 // use it for. 68 69 #define DEFINE_TRIVIAL_HASH(integral_type) \ 70 template<> \ 71 struct hash<integral_type> { \ 72 std::size_t operator()(integral_type value) const { \ 73 return static_cast<std::size_t>(value); \ 74 } \ 75 } 76 77 DEFINE_TRIVIAL_HASH(long long); 78 DEFINE_TRIVIAL_HASH(unsigned long long); 79 80 #undef DEFINE_TRIVIAL_HASH 81 #endif 82 83 // Implement string hash functions so that strings of various flavors can 84 // be used as keys in STL maps and sets. The hash algorithm comes from the 85 // GNU C++ library, in <tr1/functional>. It is duplicated here because GCC 86 // versions prior to 4.3.2 are unable to compile <tr1/functional> when RTTI 87 // is disabled, as it is in our build. 88 89 #define DEFINE_STRING_HASH(string_type) \ 90 template<> \ 91 struct hash<string_type> { \ 92 std::size_t operator()(const string_type& s) const { \ 93 std::size_t result = 0; \ 94 for (string_type::const_iterator i = s.begin(); i != s.end(); ++i) \ 95 result = (result * 131) + *i; \ 96 return result; \ 97 } \ 98 } 99 100 DEFINE_STRING_HASH(std::string); 101 DEFINE_STRING_HASH(std::wstring); 102 103 #if defined(WCHAR_T_IS_UTF32) 104 // If string16 and std::wstring are not the same type, provide a 105 // specialization for string16. 106 DEFINE_STRING_HASH(string16); 107 #endif // WCHAR_T_IS_UTF32 108 109 #undef DEFINE_STRING_HASH 110 111 } // namespace __gnu_cxx 112 113 #endif // COMPILER 114 115 #endif // BASE_HASH_TABLES_H_ 116