1 // Copyright 2016 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 #ifndef MOJO_PUBLIC_CPP_BINDINGS_LIB_WTF_HASH_UTIL_H_
6 #define MOJO_PUBLIC_CPP_BINDINGS_LIB_WTF_HASH_UTIL_H_
7
8 #include <type_traits>
9
10 #include "mojo/public/cpp/bindings/lib/hash_util.h"
11 #include "mojo/public/cpp/bindings/struct_ptr.h"
12 #include "third_party/blink/renderer/platform/wtf/hash_functions.h"
13 #include "third_party/blink/renderer/platform/wtf/text/string_hash.h"
14 #include "third_party/blink/renderer/platform/wtf/text/wtf_string.h"
15
16 namespace mojo {
17 namespace internal {
18
19 template <typename T>
WTFHashCombine(size_t seed,const T & value)20 size_t WTFHashCombine(size_t seed, const T& value) {
21 // Based on proposal in:
22 // http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2005/n1756.pdf
23 //
24 // TODO(tibell): We'd like to use WTF::DefaultHash instead of std::hash, but
25 // there is no general template specialization of DefaultHash for enums
26 // and there can't be an instance for bool.
27 return seed ^ (std::hash<T>()(value) + (seed << 6) + (seed >> 2));
28 }
29
30 template <typename T, bool has_hash_method = HasHashMethod<T>::value>
31 struct WTFHashTraits;
32
33 template <typename T>
34 size_t WTFHash(size_t seed, const T& value);
35
36 template <typename T>
37 struct WTFHashTraits<T, true> {
38 static size_t Hash(size_t seed, const T& value) { return value.Hash(seed); }
39 };
40
41 template <typename T>
42 struct WTFHashTraits<T, false> {
43 static size_t Hash(size_t seed, const T& value) {
44 return WTFHashCombine(seed, value);
45 }
46 };
47
48 template <>
49 struct WTFHashTraits<WTF::String, false> {
50 static size_t Hash(size_t seed, const WTF::String& value) {
51 return HashCombine(seed, WTF::StringHash::GetHash(value));
52 }
53 };
54
55 template <typename T>
56 size_t WTFHash(size_t seed, const T& value) {
57 return WTFHashTraits<T>::Hash(seed, value);
58 }
59
60 template <typename T>
61 struct StructPtrHashFn {
62 static unsigned GetHash(const StructPtr<T>& value) {
63 return value.Hash(kHashSeed);
64 }
65 static bool Equal(const StructPtr<T>& left, const StructPtr<T>& right) {
66 return left.Equals(right);
67 }
68 static const bool safe_to_compare_to_empty_or_deleted = false;
69 };
70
71 template <typename T>
72 struct InlinedStructPtrHashFn {
73 static unsigned GetHash(const InlinedStructPtr<T>& value) {
74 return value.Hash(kHashSeed);
75 }
76 static bool Equal(const InlinedStructPtr<T>& left,
77 const InlinedStructPtr<T>& right) {
78 return left.Equals(right);
79 }
80 static const bool safe_to_compare_to_empty_or_deleted = false;
81 };
82
83 } // namespace internal
84 } // namespace mojo
85
86 namespace WTF {
87
88 template <typename T>
89 struct DefaultHash<mojo::StructPtr<T>> {
90 using Hash = mojo::internal::StructPtrHashFn<T>;
91 };
92
93 template <typename T>
94 struct HashTraits<mojo::StructPtr<T>>
95 : public GenericHashTraits<mojo::StructPtr<T>> {
96 static const bool kHasIsEmptyValueFunction = true;
97 static bool IsEmptyValue(const mojo::StructPtr<T>& value) {
98 return value.is_null();
99 }
100 static void ConstructDeletedValue(mojo::StructPtr<T>& slot, bool) {
101 mojo::internal::StructPtrWTFHelper<T>::ConstructDeletedValue(slot);
102 }
103 static bool IsDeletedValue(const mojo::StructPtr<T>& value) {
104 return mojo::internal::StructPtrWTFHelper<T>::IsHashTableDeletedValue(
105 value);
106 }
107 };
108
109 template <typename T>
110 struct DefaultHash<mojo::InlinedStructPtr<T>> {
111 using Hash = mojo::internal::InlinedStructPtrHashFn<T>;
112 };
113
114 template <typename T>
115 struct HashTraits<mojo::InlinedStructPtr<T>>
116 : public GenericHashTraits<mojo::InlinedStructPtr<T>> {
117 static const bool kHasIsEmptyValueFunction = true;
118 static bool IsEmptyValue(const mojo::InlinedStructPtr<T>& value) {
119 return value.is_null();
120 }
121 static void ConstructDeletedValue(mojo::InlinedStructPtr<T>& slot, bool) {
122 mojo::internal::InlinedStructPtrWTFHelper<T>::ConstructDeletedValue(slot);
123 }
124 static bool IsDeletedValue(const mojo::InlinedStructPtr<T>& value) {
125 return mojo::internal::InlinedStructPtrWTFHelper<
126 T>::IsHashTableDeletedValue(value);
127 }
128 };
129
130 } // namespace WTF
131
132 #endif // MOJO_PUBLIC_CPP_BINDINGS_LIB_WTF_HASH_UTIL_H_
133