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MapVector.h
1 //===- llvm/ADT/MapVector.h - Map w/ deterministic value order --*- C++ -*-===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
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 std::vector.
14 //
15 //===----------------------------------------------------------------------===//
16 
17 #ifndef WPIUTIL_WPI_MAPVECTOR_H
18 #define WPIUTIL_WPI_MAPVECTOR_H
19 
20 #include "wpi/DenseMap.h"
21 #include "wpi/SmallVector.h"
22 #include <algorithm>
23 #include <cassert>
24 #include <cstddef>
25 #include <iterator>
26 #include <type_traits>
27 #include <utility>
28 #include <vector>
29 
30 namespace wpi {
31 
35 template<typename KeyT, typename ValueT,
36  typename MapType = DenseMap<KeyT, unsigned>,
37  typename VectorType = std::vector<std::pair<KeyT, ValueT>>>
38 class MapVector {
39  MapType Map;
40  VectorType Vector;
41 
42  static_assert(
43  std::is_integral<typename MapType::mapped_type>::value,
44  "The mapped_type of the specified Map must be an integral type");
45 
46 public:
47  using value_type = typename VectorType::value_type;
48  using size_type = typename VectorType::size_type;
49 
50  using iterator = typename VectorType::iterator;
51  using const_iterator = typename VectorType::const_iterator;
52  using reverse_iterator = typename VectorType::reverse_iterator;
53  using const_reverse_iterator = typename VectorType::const_reverse_iterator;
54 
56  VectorType takeVector() {
57  Map.clear();
58  return std::move(Vector);
59  }
60 
61  size_type size() const { return Vector.size(); }
62 
65  void reserve(size_type NumEntries) {
66  Map.reserve(NumEntries);
67  Vector.reserve(NumEntries);
68  }
69 
70  iterator begin() { return Vector.begin(); }
71  const_iterator begin() const { return Vector.begin(); }
72  iterator end() { return Vector.end(); }
73  const_iterator end() const { return Vector.end(); }
74 
75  reverse_iterator rbegin() { return Vector.rbegin(); }
76  const_reverse_iterator rbegin() const { return Vector.rbegin(); }
77  reverse_iterator rend() { return Vector.rend(); }
78  const_reverse_iterator rend() const { return Vector.rend(); }
79 
80  bool empty() const {
81  return Vector.empty();
82  }
83 
84  std::pair<KeyT, ValueT> &front() { return Vector.front(); }
85  const std::pair<KeyT, ValueT> &front() const { return Vector.front(); }
86  std::pair<KeyT, ValueT> &back() { return Vector.back(); }
87  const std::pair<KeyT, ValueT> &back() const { return Vector.back(); }
88 
89  void clear() {
90  Map.clear();
91  Vector.clear();
92  }
93 
94  void swap(MapVector &RHS) {
95  std::swap(Map, RHS.Map);
96  std::swap(Vector, RHS.Vector);
97  }
98 
99  ValueT &operator[](const KeyT &Key) {
100  std::pair<KeyT, typename MapType::mapped_type> Pair = std::make_pair(Key, 0);
101  std::pair<typename MapType::iterator, bool> Result = Map.insert(Pair);
102  auto &I = Result.first->second;
103  if (Result.second) {
104  Vector.push_back(std::make_pair(Key, ValueT()));
105  I = Vector.size() - 1;
106  }
107  return Vector[I].second;
108  }
109 
110  // Returns a copy of the value. Only allowed if ValueT is copyable.
111  ValueT lookup(const KeyT &Key) const {
112  static_assert(std::is_copy_constructible<ValueT>::value,
113  "Cannot call lookup() if ValueT is not copyable.");
114  typename MapType::const_iterator Pos = Map.find(Key);
115  return Pos == Map.end()? ValueT() : Vector[Pos->second].second;
116  }
117 
118  std::pair<iterator, bool> insert(const std::pair<KeyT, ValueT> &KV) {
119  std::pair<KeyT, typename MapType::mapped_type> Pair = std::make_pair(KV.first, 0);
120  std::pair<typename MapType::iterator, bool> Result = Map.insert(Pair);
121  auto &I = Result.first->second;
122  if (Result.second) {
123  Vector.push_back(std::make_pair(KV.first, KV.second));
124  I = Vector.size() - 1;
125  return std::make_pair(std::prev(end()), true);
126  }
127  return std::make_pair(begin() + I, false);
128  }
129 
130  std::pair<iterator, bool> insert(std::pair<KeyT, ValueT> &&KV) {
131  // Copy KV.first into the map, then move it into the vector.
132  std::pair<KeyT, typename MapType::mapped_type> Pair = std::make_pair(KV.first, 0);
133  std::pair<typename MapType::iterator, bool> Result = Map.insert(Pair);
134  auto &I = Result.first->second;
135  if (Result.second) {
136  Vector.push_back(std::move(KV));
137  I = Vector.size() - 1;
138  return std::make_pair(std::prev(end()), true);
139  }
140  return std::make_pair(begin() + I, false);
141  }
142 
143  size_type count(const KeyT &Key) const {
144  typename MapType::const_iterator Pos = Map.find(Key);
145  return Pos == Map.end()? 0 : 1;
146  }
147 
148  iterator find(const KeyT &Key) {
149  typename MapType::const_iterator Pos = Map.find(Key);
150  return Pos == Map.end()? Vector.end() :
151  (Vector.begin() + Pos->second);
152  }
153 
154  const_iterator find(const KeyT &Key) const {
155  typename MapType::const_iterator Pos = Map.find(Key);
156  return Pos == Map.end()? Vector.end() :
157  (Vector.begin() + Pos->second);
158  }
159 
161  void pop_back() {
162  typename MapType::iterator Pos = Map.find(Vector.back().first);
163  Map.erase(Pos);
164  Vector.pop_back();
165  }
166 
174  typename VectorType::iterator erase(typename VectorType::iterator Iterator) {
175  Map.erase(Iterator->first);
176  auto Next = Vector.erase(Iterator);
177  if (Next == Vector.end())
178  return Next;
179 
180  // Update indices in the map.
181  size_t Index = Next - Vector.begin();
182  for (auto &I : Map) {
183  assert(I.second != Index && "Index was already erased!");
184  if (I.second > Index)
185  --I.second;
186  }
187  return Next;
188  }
189 
193  size_type erase(const KeyT &Key) {
194  auto Iterator = find(Key);
195  if (Iterator == end())
196  return 0;
197  erase(Iterator);
198  return 1;
199  }
200 
205  template <class Predicate> void remove_if(Predicate Pred);
206 };
207 
208 template <typename KeyT, typename ValueT, typename MapType, typename VectorType>
209 template <class Function>
211  auto O = Vector.begin();
212  for (auto I = O, E = Vector.end(); I != E; ++I) {
213  if (Pred(*I)) {
214  // Erase from the map.
215  Map.erase(I->first);
216  continue;
217  }
218 
219  if (I != O) {
220  // Move the value and update the index in the map.
221  *O = std::move(*I);
222  Map[O->first] = O - Vector.begin();
223  }
224  ++O;
225  }
226  // Erase trailing entries in the vector.
227  Vector.erase(O, Vector.end());
228 }
229 
232 template <typename KeyT, typename ValueT, unsigned N>
234  : MapVector<KeyT, ValueT, SmallDenseMap<KeyT, unsigned, N>,
235  SmallVector<std::pair<KeyT, ValueT>, N>> {
236 };
237 
238 } // end namespace wpi
239 
240 #endif // LLVM_ADT_MAPVECTOR_H
friend reverse_iterator rbegin(StringRef path, Style style)
Get reverse begin iterator over path.
friend reverse_iterator rend(StringRef path)
Get reverse end iterator over path.
This class implements a map that also provides access to all stored values in a deterministic order...
Definition: MapVector.h:38
WPILib C++ utilities (wpiutil) namespace.
Definition: SmallString.h:21
friend const_iterator end(StringRef path)
Get end iterator over path.
friend const_iterator begin(StringRef path, Style style)
Get begin iterator over path.
auto find(R &&Range, const T &Val) -> decltype(adl_begin(Range))
Provide wrappers to std::find which take ranges instead of having to pass begin/end explicitly...
Definition: STLExtras.h:896
auto size(R &&Range, typename std::enable_if< std::is_same< typename std::iterator_traits< decltype(Range.begin())>::iterator_category, std::random_access_iterator_tag >::value, void >::type *=nullptr) -> decltype(std::distance(Range.begin(), Range.end()))
Get the size of a range.
Definition: STLExtras.h:999
A MapVector that performs no allocations if smaller than a certain size.
Definition: MapVector.h:233
auto count(R &&Range, const E &Element) -> typename std::iterator_traits< decltype(adl_begin(Range))>::difference_type
Wrapper function around std::count to count the number of times an element Element occurs in the give...
Definition: STLExtras.h:941
auto remove_if(R &&Range, UnaryPredicate P) -> decltype(adl_begin(Range))
Provide wrappers to std::remove_if which take ranges instead of having to pass begin/end explicitly...
Definition: STLExtras.h:915