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 :
15 : #ifndef BASE_HASH_TABLES_H_
16 : #define BASE_HASH_TABLES_H_
17 :
18 : #include "build/build_config.h"
19 :
20 : #include "base/string16.h"
21 :
22 : #if defined(COMPILER_MSVC) || (defined(ANDROID) && defined(_STLP_STD_NAME))
23 : #include <hash_map>
24 : #include <hash_set>
25 : namespace base {
26 : #ifdef ANDROID
27 : using _STLP_STD_NAME::hash_map;
28 : using _STLP_STD_NAME::hash_set;
29 : #else
30 : using stdext::hash_map;
31 : using stdext::hash_set;
32 : #endif
33 : }
34 : #elif defined(COMPILER_GCC)
35 : // This is a hack to disable the gcc 4.4 warning about hash_map and hash_set
36 : // being deprecated. We can get rid of this when we upgrade to VS2008 and we
37 : // can use <tr1/unordered_map> and <tr1/unordered_set>.
38 : #ifdef __DEPRECATED
39 : #define CHROME_OLD__DEPRECATED __DEPRECATED
40 : #undef __DEPRECATED
41 : #endif
42 :
43 : #include <ext/hash_map>
44 : #include <ext/hash_set>
45 : #include <string>
46 :
47 : #ifdef CHROME_OLD__DEPRECATED
48 : #define __DEPRECATED CHROME_OLD__DEPRECATED
49 : #undef CHROME_OLD__DEPRECATED
50 : #endif
51 :
52 : namespace base {
53 : using __gnu_cxx::hash_map;
54 : using __gnu_cxx::hash_set;
55 : } // namespace base
56 :
57 : namespace __gnu_cxx {
58 :
59 : // The GNU C++ library provides identiy hash functions for many integral types,
60 : // but not for |long long|. This hash function will truncate if |size_t| is
61 : // narrower than |long long|. This is probably good enough for what we will
62 : // use it for.
63 :
64 : #define DEFINE_TRIVIAL_HASH(integral_type) \
65 : template<> \
66 : struct hash<integral_type> { \
67 : std::size_t operator()(integral_type value) const { \
68 : return static_cast<std::size_t>(value); \
69 : } \
70 : }
71 :
72 : DEFINE_TRIVIAL_HASH(long long);
73 : DEFINE_TRIVIAL_HASH(unsigned long long);
74 :
75 : #undef DEFINE_TRIVIAL_HASH
76 :
77 : // Implement string hash functions so that strings of various flavors can
78 : // be used as keys in STL maps and sets. The hash algorithm comes from the
79 : // GNU C++ library, in <tr1/functional>. It is duplicated here because GCC
80 : // versions prior to 4.3.2 are unable to compile <tr1/functional> when RTTI
81 : // is disabled, as it is in our build.
82 :
83 : #define DEFINE_STRING_HASH(string_type) \
84 : template<> \
85 : struct hash<string_type> { \
86 : std::size_t operator()(const string_type& s) const { \
87 : std::size_t result = 0; \
88 : for (string_type::const_iterator i = s.begin(); i != s.end(); ++i) \
89 : result = (result * 131) + *i; \
90 : return result; \
91 : } \
92 : }
93 :
94 0 : DEFINE_STRING_HASH(std::string);
95 : DEFINE_STRING_HASH(std::wstring);
96 :
97 : #if defined(WCHAR_T_IS_UTF32)
98 : // If string16 and std::wstring are not the same type, provide a
99 : // specialization for string16.
100 : DEFINE_STRING_HASH(string16);
101 : #endif // WCHAR_T_IS_UTF32
102 :
103 : #undef DEFINE_STRING_HASH
104 :
105 : } // namespace __gnu_cxx
106 :
107 : #endif // COMPILER
108 :
109 : #endif // BASE_HASH_TABLES_H_
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