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> 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
