1 // Copyright 2018 The Abseil Authors. 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // https://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 15 #ifndef ABSL_CONTAINER_INTERNAL_RAW_HASH_MAP_H_ 16 #define ABSL_CONTAINER_INTERNAL_RAW_HASH_MAP_H_ 17 18 #include <tuple> 19 #include <type_traits> 20 #include <utility> 21 22 #include "absl/base/internal/throw_delegate.h" 23 #include "absl/container/internal/container_memory.h" 24 #include "absl/container/internal/raw_hash_set.h" // IWYU pragma: export 25 26 namespace absl { 27 ABSL_NAMESPACE_BEGIN 28 namespace container_internal { 29 30 template <class Policy, class Hash, class Eq, class Alloc> 31 class raw_hash_map : public raw_hash_set<Policy, Hash, Eq, Alloc> { 32 // P is Policy. It's passed as a template argument to support maps that have 33 // incomplete types as values, as in unordered_map<K, IncompleteType>. 34 // MappedReference<> may be a non-reference type. 35 template <class P> 36 using MappedReference = decltype(P::value( 37 std::addressof(std::declval<typename raw_hash_map::reference>()))); 38 39 // MappedConstReference<> may be a non-reference type. 40 template <class P> 41 using MappedConstReference = decltype(P::value( 42 std::addressof(std::declval<typename raw_hash_map::const_reference>()))); 43 44 using KeyArgImpl = 45 KeyArg<IsTransparent<Eq>::value && IsTransparent<Hash>::value>; 46 47 public: 48 using key_type = typename Policy::key_type; 49 using mapped_type = typename Policy::mapped_type; 50 template <class K> 51 using key_arg = typename KeyArgImpl::template type<K, key_type>; 52 53 static_assert(!std::is_reference<key_type>::value, ""); 54 // TODO(alkis): remove this assertion and verify that reference mapped_type is 55 // supported. 56 static_assert(!std::is_reference<mapped_type>::value, ""); 57 58 using iterator = typename raw_hash_map::raw_hash_set::iterator; 59 using const_iterator = typename raw_hash_map::raw_hash_set::const_iterator; 60 raw_hash_map()61 raw_hash_map() {} 62 using raw_hash_map::raw_hash_set::raw_hash_set; 63 64 // The last two template parameters ensure that both arguments are rvalues 65 // (lvalue arguments are handled by the overloads below). This is necessary 66 // for supporting bitfield arguments. 67 // 68 // union { int n : 1; }; 69 // flat_hash_map<int, int> m; 70 // m.insert_or_assign(n, n); 71 template <class K = key_type, class V = mapped_type, K* = nullptr, 72 V* = nullptr> insert_or_assign(key_arg<K> && k,V && v)73 std::pair<iterator, bool> insert_or_assign(key_arg<K>&& k, V&& v) { 74 return insert_or_assign_impl(std::forward<K>(k), std::forward<V>(v)); 75 } 76 77 template <class K = key_type, class V = mapped_type, K* = nullptr> insert_or_assign(key_arg<K> && k,const V & v)78 std::pair<iterator, bool> insert_or_assign(key_arg<K>&& k, const V& v) { 79 return insert_or_assign_impl(std::forward<K>(k), v); 80 } 81 82 template <class K = key_type, class V = mapped_type, V* = nullptr> insert_or_assign(const key_arg<K> & k,V && v)83 std::pair<iterator, bool> insert_or_assign(const key_arg<K>& k, V&& v) { 84 return insert_or_assign_impl(k, std::forward<V>(v)); 85 } 86 87 template <class K = key_type, class V = mapped_type> insert_or_assign(const key_arg<K> & k,const V & v)88 std::pair<iterator, bool> insert_or_assign(const key_arg<K>& k, const V& v) { 89 return insert_or_assign_impl(k, v); 90 } 91 92 template <class K = key_type, class V = mapped_type, K* = nullptr, 93 V* = nullptr> insert_or_assign(const_iterator,key_arg<K> && k,V && v)94 iterator insert_or_assign(const_iterator, key_arg<K>&& k, V&& v) { 95 return insert_or_assign(std::forward<K>(k), std::forward<V>(v)).first; 96 } 97 98 template <class K = key_type, class V = mapped_type, K* = nullptr> insert_or_assign(const_iterator,key_arg<K> && k,const V & v)99 iterator insert_or_assign(const_iterator, key_arg<K>&& k, const V& v) { 100 return insert_or_assign(std::forward<K>(k), v).first; 101 } 102 103 template <class K = key_type, class V = mapped_type, V* = nullptr> insert_or_assign(const_iterator,const key_arg<K> & k,V && v)104 iterator insert_or_assign(const_iterator, const key_arg<K>& k, V&& v) { 105 return insert_or_assign(k, std::forward<V>(v)).first; 106 } 107 108 template <class K = key_type, class V = mapped_type> insert_or_assign(const_iterator,const key_arg<K> & k,const V & v)109 iterator insert_or_assign(const_iterator, const key_arg<K>& k, const V& v) { 110 return insert_or_assign(k, v).first; 111 } 112 113 // All `try_emplace()` overloads make the same guarantees regarding rvalue 114 // arguments as `std::unordered_map::try_emplace()`, namely that these 115 // functions will not move from rvalue arguments if insertions do not happen. 116 template <class K = key_type, class... Args, 117 typename std::enable_if< 118 !std::is_convertible<K, const_iterator>::value, int>::type = 0, 119 K* = nullptr> try_emplace(key_arg<K> && k,Args &&...args)120 std::pair<iterator, bool> try_emplace(key_arg<K>&& k, Args&&... args) { 121 return try_emplace_impl(std::forward<K>(k), std::forward<Args>(args)...); 122 } 123 124 template <class K = key_type, class... Args, 125 typename std::enable_if< 126 !std::is_convertible<K, const_iterator>::value, int>::type = 0> try_emplace(const key_arg<K> & k,Args &&...args)127 std::pair<iterator, bool> try_emplace(const key_arg<K>& k, Args&&... args) { 128 return try_emplace_impl(k, std::forward<Args>(args)...); 129 } 130 131 template <class K = key_type, class... Args, K* = nullptr> try_emplace(const_iterator,key_arg<K> && k,Args &&...args)132 iterator try_emplace(const_iterator, key_arg<K>&& k, Args&&... args) { 133 return try_emplace(std::forward<K>(k), std::forward<Args>(args)...).first; 134 } 135 136 template <class K = key_type, class... Args> try_emplace(const_iterator,const key_arg<K> & k,Args &&...args)137 iterator try_emplace(const_iterator, const key_arg<K>& k, Args&&... args) { 138 return try_emplace(k, std::forward<Args>(args)...).first; 139 } 140 141 template <class K = key_type, class P = Policy> at(const key_arg<K> & key)142 MappedReference<P> at(const key_arg<K>& key) { 143 auto it = this->find(key); 144 if (it == this->end()) { 145 base_internal::ThrowStdOutOfRange( 146 "absl::container_internal::raw_hash_map<>::at"); 147 } 148 return Policy::value(&*it); 149 } 150 151 template <class K = key_type, class P = Policy> at(const key_arg<K> & key)152 MappedConstReference<P> at(const key_arg<K>& key) const { 153 auto it = this->find(key); 154 if (it == this->end()) { 155 base_internal::ThrowStdOutOfRange( 156 "absl::container_internal::raw_hash_map<>::at"); 157 } 158 return Policy::value(&*it); 159 } 160 161 template <class K = key_type, class P = Policy, K* = nullptr> 162 MappedReference<P> operator[](key_arg<K>&& key) { 163 return Policy::value(&*try_emplace(std::forward<K>(key)).first); 164 } 165 166 template <class K = key_type, class P = Policy> 167 MappedReference<P> operator[](const key_arg<K>& key) { 168 return Policy::value(&*try_emplace(key).first); 169 } 170 171 private: 172 template <class K, class V> insert_or_assign_impl(K && k,V && v)173 std::pair<iterator, bool> insert_or_assign_impl(K&& k, V&& v) { 174 auto res = this->find_or_prepare_insert(k); 175 if (res.second) 176 this->emplace_at(res.first, std::forward<K>(k), std::forward<V>(v)); 177 else 178 Policy::value(&*this->iterator_at(res.first)) = std::forward<V>(v); 179 return {this->iterator_at(res.first), res.second}; 180 } 181 182 template <class K = key_type, class... Args> try_emplace_impl(K && k,Args &&...args)183 std::pair<iterator, bool> try_emplace_impl(K&& k, Args&&... args) { 184 auto res = this->find_or_prepare_insert(k); 185 if (res.second) 186 this->emplace_at(res.first, std::piecewise_construct, 187 std::forward_as_tuple(std::forward<K>(k)), 188 std::forward_as_tuple(std::forward<Args>(args)...)); 189 return {this->iterator_at(res.first), res.second}; 190 } 191 }; 192 193 } // namespace container_internal 194 ABSL_NAMESPACE_END 195 } // namespace absl 196 197 #endif // ABSL_CONTAINER_INTERNAL_RAW_HASH_MAP_H_ 198