2 * Copyright 2016 Facebook, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
16 // Copyright 2013-present Facebook. All Rights Reserved.
17 // @author: Pavlo Kushnir (pavlo)
21 #include <initializer_list>
23 #include <unordered_map>
24 #include <folly/Range.h>
25 #include <folly/experimental/StringKeyedCommon.h>
30 * Wrapper class for unordered_map<string, Value> that can
31 * perform lookup operations with StringPiece, not only string.
33 * It uses kind of hack: string pointed by StringPiece is copied when
34 * StringPiece is inserted into map
36 template <class Value,
37 class Hash = StringPieceHash,
38 class Eq = std::equal_to<StringPiece>,
39 class Alloc = std::allocator<std::pair<const StringPiece, Value>>>
40 class StringKeyedUnorderedMap
41 : private std::unordered_map<StringPiece, Value, Hash, Eq, Alloc> {
43 using Base = std::unordered_map<StringPiece, Value, Hash, Eq, Alloc>;
46 typedef typename Base::key_type key_type;
47 typedef typename Base::mapped_type mapped_type;
48 typedef typename Base::value_type value_type;
49 typedef typename Base::hasher hasher;
50 typedef typename Base::key_equal key_equal;
51 typedef typename Base::allocator_type allocator_type;
52 typedef typename Base::reference reference;
53 typedef typename Base::const_reference const_reference;
54 typedef typename Base::pointer pointer;
55 typedef typename Base::const_pointer const_pointer;
56 typedef typename Base::iterator iterator;
57 typedef typename Base::const_iterator const_iterator;
58 typedef typename Base::size_type size_type;
59 typedef typename Base::difference_type difference_type;
61 explicit StringKeyedUnorderedMap() = default;
63 explicit StringKeyedUnorderedMap(
65 const hasher& hf = hasher(),
66 const key_equal& eql = key_equal(),
67 const allocator_type& alloc = allocator_type())
68 : Base(n, hf, eql, alloc) {
71 explicit StringKeyedUnorderedMap(const allocator_type& a)
75 template <class InputIterator>
76 StringKeyedUnorderedMap(InputIterator b, InputIterator e) {
78 // insert() will carry the duplication
79 emplace(b->first, b->second);
83 template <class InputIterator>
84 StringKeyedUnorderedMap(
85 InputIterator b, InputIterator e,
87 const hasher& hf = hasher(),
88 const key_equal& eql = key_equal(),
89 const allocator_type& alloc = allocator_type())
90 : Base(n, hf, eql, alloc) {
92 // insert() will carry the duplication
93 emplace(b->first, b->second);
97 StringKeyedUnorderedMap(const StringKeyedUnorderedMap& rhs)
98 : StringKeyedUnorderedMap(rhs.begin(), rhs.end(),
102 rhs.get_allocator()) {
105 StringKeyedUnorderedMap(StringKeyedUnorderedMap&& rhs) noexcept
106 : StringKeyedUnorderedMap(std::move(rhs), rhs.get_allocator()) {
109 StringKeyedUnorderedMap(StringKeyedUnorderedMap&& other,
110 const allocator_type& /* a */) noexcept
111 : Base(std::move(other) /*, a*/ /* not supported by gcc */) {}
113 StringKeyedUnorderedMap(std::initializer_list<value_type> il)
114 : StringKeyedUnorderedMap(il.begin(), il.end()) {
117 StringKeyedUnorderedMap(
118 std::initializer_list<value_type> il,
120 const hasher& hf = hasher(),
121 const key_equal& eql = key_equal(),
122 const allocator_type& alloc = allocator_type())
123 : StringKeyedUnorderedMap(il.begin(), il.end(), n, hf, eql, alloc) {
126 StringKeyedUnorderedMap& operator=(const StringKeyedUnorderedMap& other) & {
127 if (this == &other) {
130 return *this = StringKeyedUnorderedMap(other);
133 StringKeyedUnorderedMap&
134 operator=(StringKeyedUnorderedMap&& other) & noexcept {
135 assert(this != &other);
137 Base::operator=(std::move(other));
143 using Base::max_size;
149 bool operator==(const StringKeyedUnorderedMap& rhs) {
150 const Base& lhs = *this;
154 // No need for copy/move overload as StringPiece is small struct.
155 mapped_type& operator[](StringPiece key) {
160 // operator[] will create new (key, value) pair
161 // we need to allocate memory for key
162 return Base::operator[](stringPieceDup(key, get_allocator()));
169 template <class... Args>
170 std::pair<iterator, bool> emplace(StringPiece key, Args&&... args) {
175 return Base::emplace(stringPieceDup(key, get_allocator()),
176 std::forward<Args>(args)...);
179 std::pair<iterator, bool> insert(value_type val) {
180 auto it = find(val.first);
184 auto valCopy = std::make_pair(stringPieceDup(val.first, get_allocator()),
185 std::move(val.second));
186 return Base::insert(valCopy);
189 iterator erase(const_iterator position) {
190 auto key = position->first;
191 auto result = Base::erase(position);
192 stringPieceDel(key, get_allocator());
196 size_type erase(StringPiece key) {
205 void clear() noexcept {
206 for (auto& it : *this) {
207 stringPieceDel(it.first, get_allocator());
213 using Base::hash_function;
215 using Base::get_allocator;
216 using Base::bucket_count;
217 using Base::max_bucket_count;
218 using Base::bucket_size;
221 ~StringKeyedUnorderedMap() {
222 // Here we assume that unordered_map doesn't use keys in destructor
223 for (auto& it : *this) {
224 stringPieceDel(it.first, get_allocator());