1//===- llvm/ADT/MapVector.h - Map w/ deterministic value order --*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8///
9/// \file
10/// This file implements a map that provides insertion order iteration. The
11/// interface is purposefully minimal. The key is assumed to be cheap to copy
12/// and 2 copies are kept, one for indexing in a DenseMap, one for iteration in
13/// a SmallVector.
14///
15//===----------------------------------------------------------------------===//
16
17#ifndef LLVM_ADT_MAPVECTOR_H
18#define LLVM_ADT_MAPVECTOR_H
19
20#include "llvm/ADT/DenseMap.h"
21#include "llvm/ADT/SmallVector.h"
22#include <cassert>
23#include <cstddef>
24#include <iterator>
25#include <type_traits>
26#include <utility>
27
28namespace llvm {
29
30/// This class implements a map that also provides access to all stored values
31/// in a deterministic order. The values are kept in a SmallVector<*, 0> and the
32/// mapping is done with DenseMap from Keys to indexes in that vector.
33template <typename KeyT, typename ValueT,
34 typename MapType = DenseMap<KeyT, unsigned>,
35 typename VectorType = SmallVector<std::pair<KeyT, ValueT>, 0>>
36class MapVector {
37 MapType Map;
38 VectorType Vector;
39
40 static_assert(
41 std::is_integral_v<typename MapType::mapped_type>,
42 "The mapped_type of the specified Map must be an integral type");
43
44public:
45 using key_type = KeyT;
46 using value_type = typename VectorType::value_type;
47 using size_type = typename VectorType::size_type;
48
49 using iterator = typename VectorType::iterator;
50 using const_iterator = typename VectorType::const_iterator;
51 using reverse_iterator = typename VectorType::reverse_iterator;
52 using const_reverse_iterator = typename VectorType::const_reverse_iterator;
53
54 /// Clear the MapVector and return the underlying vector.
55 VectorType takeVector() {
56 Map.clear();
57 return std::move(Vector);
58 }
59
60 size_type size() const { return Vector.size(); }
61
62 /// Grow the MapVector so that it can contain at least \p NumEntries items
63 /// before resizing again.
64 void reserve(size_type NumEntries) {
65 Map.reserve(NumEntries);
66 Vector.reserve(NumEntries);
67 }
68
69 iterator begin() { return Vector.begin(); }
70 const_iterator begin() const { return Vector.begin(); }
71 iterator end() { return Vector.end(); }
72 const_iterator end() const { return Vector.end(); }
73
74 reverse_iterator rbegin() { return Vector.rbegin(); }
75 const_reverse_iterator rbegin() const { return Vector.rbegin(); }
76 reverse_iterator rend() { return Vector.rend(); }
77 const_reverse_iterator rend() const { return Vector.rend(); }
78
79 bool empty() const {
80 return Vector.empty();
81 }
82
83 std::pair<KeyT, ValueT> &front() { return Vector.front(); }
84 const std::pair<KeyT, ValueT> &front() const { return Vector.front(); }
85 std::pair<KeyT, ValueT> &back() { return Vector.back(); }
86 const std::pair<KeyT, ValueT> &back() const { return Vector.back(); }
87
88 void clear() {
89 Map.clear();
90 Vector.clear();
91 }
92
93 void swap(MapVector &RHS) {
94 std::swap(Map, RHS.Map);
95 std::swap(Vector, RHS.Vector);
96 }
97
98 ValueT &operator[](const KeyT &Key) {
99 std::pair<KeyT, typename MapType::mapped_type> Pair = std::make_pair(Key, 0);
100 std::pair<typename MapType::iterator, bool> Result = Map.insert(Pair);
101 auto &I = Result.first->second;
102 if (Result.second) {
103 Vector.push_back(std::make_pair(Key, ValueT()));
104 I = Vector.size() - 1;
105 }
106 return Vector[I].second;
107 }
108
109 // Returns a copy of the value. Only allowed if ValueT is copyable.
110 ValueT lookup(const KeyT &Key) const {
111 static_assert(std::is_copy_constructible_v<ValueT>,
112 "Cannot call lookup() if ValueT is not copyable.");
113 typename MapType::const_iterator Pos = Map.find(Key);
114 return Pos == Map.end()? ValueT() : Vector[Pos->second].second;
115 }
116
117 template <typename... Ts>
118 std::pair<iterator, bool> try_emplace(const KeyT &Key, Ts &&...Args) {
119 auto [It, Inserted] = Map.insert(std::make_pair(Key, 0));
120 if (Inserted) {
121 It->second = Vector.size();
122 Vector.emplace_back(std::piecewise_construct, std::forward_as_tuple(Key),
123 std::forward_as_tuple(std::forward<Ts>(Args)...));
124 return std::make_pair(std::prev(end()), true);
125 }
126 return std::make_pair(begin() + It->second, false);
127 }
128 template <typename... Ts>
129 std::pair<iterator, bool> try_emplace(KeyT &&Key, Ts &&...Args) {
130 auto [It, Inserted] = Map.insert(std::make_pair(Key, 0));
131 if (Inserted) {
132 It->second = Vector.size();
133 Vector.emplace_back(std::piecewise_construct,
134 std::forward_as_tuple(std::move(Key)),
135 std::forward_as_tuple(std::forward<Ts>(Args)...));
136 return std::make_pair(std::prev(end()), true);
137 }
138 return std::make_pair(begin() + It->second, false);
139 }
140
141 std::pair<iterator, bool> insert(const std::pair<KeyT, ValueT> &KV) {
142 return try_emplace(KV.first, KV.second);
143 }
144 std::pair<iterator, bool> insert(std::pair<KeyT, ValueT> &&KV) {
145 return try_emplace(std::move(KV.first), std::move(KV.second));
146 }
147
148 template <typename V>
149 std::pair<iterator, bool> insert_or_assign(const KeyT &Key, V &&Val) {
150 auto Ret = try_emplace(Key, std::forward<V>(Val));
151 if (!Ret.second)
152 Ret.first->second = std::forward<V>(Val);
153 return Ret;
154 }
155 template <typename V>
156 std::pair<iterator, bool> insert_or_assign(KeyT &&Key, V &&Val) {
157 auto Ret = try_emplace(std::move(Key), std::forward<V>(Val));
158 if (!Ret.second)
159 Ret.first->second = std::forward<V>(Val);
160 return Ret;
161 }
162
163 bool contains(const KeyT &Key) const { return Map.find(Key) != Map.end(); }
164
165 size_type count(const KeyT &Key) const { return contains(Key) ? 1 : 0; }
166
167 iterator find(const KeyT &Key) {
168 typename MapType::const_iterator Pos = Map.find(Key);
169 return Pos == Map.end()? Vector.end() :
170 (Vector.begin() + Pos->second);
171 }
172
173 const_iterator find(const KeyT &Key) const {
174 typename MapType::const_iterator Pos = Map.find(Key);
175 return Pos == Map.end()? Vector.end() :
176 (Vector.begin() + Pos->second);
177 }
178
179 /// Remove the last element from the vector.
180 void pop_back() {
181 typename MapType::iterator Pos = Map.find(Vector.back().first);
182 Map.erase(Pos);
183 Vector.pop_back();
184 }
185
186 /// Remove the element given by Iterator.
187 ///
188 /// Returns an iterator to the element following the one which was removed,
189 /// which may be end().
190 ///
191 /// \note This is a deceivingly expensive operation (linear time). It's
192 /// usually better to use \a remove_if() if possible.
193 typename VectorType::iterator erase(typename VectorType::iterator Iterator) {
194 Map.erase(Iterator->first);
195 auto Next = Vector.erase(Iterator);
196 if (Next == Vector.end())
197 return Next;
198
199 // Update indices in the map.
200 size_t Index = Next - Vector.begin();
201 for (auto &I : Map) {
202 assert(I.second != Index && "Index was already erased!");
203 if (I.second > Index)
204 --I.second;
205 }
206 return Next;
207 }
208
209 /// Remove all elements with the key value Key.
210 ///
211 /// Returns the number of elements removed.
212 size_type erase(const KeyT &Key) {
213 auto Iterator = find(Key);
214 if (Iterator == end())
215 return 0;
216 erase(Iterator);
217 return 1;
218 }
219
220 /// Remove the elements that match the predicate.
221 ///
222 /// Erase all elements that match \c Pred in a single pass. Takes linear
223 /// time.
224 template <class Predicate> void remove_if(Predicate Pred);
225};
226
227template <typename KeyT, typename ValueT, typename MapType, typename VectorType>
228template <class Function>
229void MapVector<KeyT, ValueT, MapType, VectorType>::remove_if(Function Pred) {
230 auto O = Vector.begin();
231 for (auto I = O, E = Vector.end(); I != E; ++I) {
232 if (Pred(*I)) {
233 // Erase from the map.
234 Map.erase(I->first);
235 continue;
236 }
237
238 if (I != O) {
239 // Move the value and update the index in the map.
240 *O = std::move(*I);
241 Map[O->first] = O - Vector.begin();
242 }
243 ++O;
244 }
245 // Erase trailing entries in the vector.
246 Vector.erase(O, Vector.end());
247}
248
249/// A MapVector that performs no allocations if smaller than a certain
250/// size.
251template <typename KeyT, typename ValueT, unsigned N>
252struct SmallMapVector
253 : MapVector<KeyT, ValueT, SmallDenseMap<KeyT, unsigned, N>,
254 SmallVector<std::pair<KeyT, ValueT>, N>> {
255};
256
257} // end namespace llvm
258
259#endif // LLVM_ADT_MAPVECTOR_H
260

source code of include/llvm-20/llvm/ADT/MapVector.h