1//===- llvm/ADT/SetVector.h - Set with insert order iteration ---*- 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 set that has insertion order iteration
11// characteristics. This is useful for keeping a set of things that need to be
12// visited later but in a deterministic order (insertion order). The interface
13// is purposefully minimal.
14//
15// This file defines SetVector and SmallSetVector, which performs no allocations
16// if the SetVector has less than a certain number of elements.
17//
18//===----------------------------------------------------------------------===//
19
20#ifndef LLVM_ADT_SETVECTOR_H
21#define LLVM_ADT_SETVECTOR_H
22
23#include "llvm/ADT/DenseSet.h"
24#include "llvm/ADT/SmallSet.h"
25#include <algorithm>
26#include <cassert>
27#include <vector>
28
29namespace llvm {
30
31/// \brief A vector that has set insertion semantics.
32///
33/// This adapter class provides a way to keep a set of things that also has the
34/// property of a deterministic iteration order. The order of iteration is the
35/// order of insertion.
36template <typename T, typename Vector = std::vector<T>,
37          typename Set = DenseSet<T>>
38class SetVector {
39public:
40  typedef T value_type;
41  typedef T key_type;
42  typedef T& reference;
43  typedef const T& const_reference;
44  typedef Set set_type;
45  typedef Vector vector_type;
46  typedef typename vector_type::const_iterator iterator;
47  typedef typename vector_type::const_iterator const_iterator;
48  typedef typename vector_type::const_reverse_iterator reverse_iterator;
49  typedef typename vector_type::const_reverse_iterator const_reverse_iterator;
50  typedef typename vector_type::size_type size_type;
51
52  /// \brief Construct an empty SetVector
53  SetVector() {}
54
55  /// \brief Initialize a SetVector with a range of elements
56  template<typename It>
57  SetVector(It Start, It End) {
58    insert(Start, End);
59  }
60
61  ArrayRef<T> getArrayRef() const { return vector_; }
62
63  /// \brief Determine if the SetVector is empty or not.
64  bool empty() const {
65    return vector_.empty();
66  }
67
68  /// \brief Determine the number of elements in the SetVector.
69  size_type size() const {
70    return vector_.size();
71  }
72
73  /// \brief Get an iterator to the beginning of the SetVector.
74  iterator begin() {
75    return vector_.begin();
76  }
77
78  /// \brief Get a const_iterator to the beginning of the SetVector.
79  const_iterator begin() const {
80    return vector_.begin();
81  }
82
83  /// \brief Get an iterator to the end of the SetVector.
84  iterator end() {
85    return vector_.end();
86  }
87
88  /// \brief Get a const_iterator to the end of the SetVector.
89  const_iterator end() const {
90    return vector_.end();
91  }
92
93  /// \brief Get an reverse_iterator to the end of the SetVector.
94  reverse_iterator rbegin() {
95    return vector_.rbegin();
96  }
97
98  /// \brief Get a const_reverse_iterator to the end of the SetVector.
99  const_reverse_iterator rbegin() const {
100    return vector_.rbegin();
101  }
102
103  /// \brief Get a reverse_iterator to the beginning of the SetVector.
104  reverse_iterator rend() {
105    return vector_.rend();
106  }
107
108  /// \brief Get a const_reverse_iterator to the beginning of the SetVector.
109  const_reverse_iterator rend() const {
110    return vector_.rend();
111  }
112
113  /// \brief Return the last element of the SetVector.
114  const T &back() const {
115    assert(!empty() && "Cannot call back() on empty SetVector!");
116    return vector_.back();
117  }
118
119  /// \brief Index into the SetVector.
120  const_reference operator[](size_type n) const {
121    assert(n < vector_.size() && "SetVector access out of range!");
122    return vector_[n];
123  }
124
125  /// \brief Insert a new element into the SetVector.
126  /// \returns true iff the element was inserted into the SetVector.
127  bool insert(const value_type &X) {
128    bool result = set_.insert(X).second;
129    if (result)
130      vector_.push_back(X);
131    return result;
132  }
133
134  /// \brief Insert a range of elements into the SetVector.
135  template<typename It>
136  void insert(It Start, It End) {
137    for (; Start != End; ++Start)
138      if (set_.insert(*Start).second)
139        vector_.push_back(*Start);
140  }
141
142  /// \brief Remove an item from the set vector.
143  bool remove(const value_type& X) {
144    if (set_.erase(X)) {
145      typename vector_type::iterator I =
146        std::find(vector_.begin(), vector_.end(), X);
147      assert(I != vector_.end() && "Corrupted SetVector instances!");
148      vector_.erase(I);
149      return true;
150    }
151    return false;
152  }
153
154  /// \brief Remove items from the set vector based on a predicate function.
155  ///
156  /// This is intended to be equivalent to the following code, if we could
157  /// write it:
158  ///
159  /// \code
160  ///   V.erase(std::remove_if(V.begin(), V.end(), P), V.end());
161  /// \endcode
162  ///
163  /// However, SetVector doesn't expose non-const iterators, making any
164  /// algorithm like remove_if impossible to use.
165  ///
166  /// \returns true if any element is removed.
167  template <typename UnaryPredicate>
168  bool remove_if(UnaryPredicate P) {
169    typename vector_type::iterator I
170      = std::remove_if(vector_.begin(), vector_.end(),
171                       TestAndEraseFromSet<UnaryPredicate>(P, set_));
172    if (I == vector_.end())
173      return false;
174    vector_.erase(I, vector_.end());
175    return true;
176  }
177
178  /// \brief Count the number of elements of a given key in the SetVector.
179  /// \returns 0 if the element is not in the SetVector, 1 if it is.
180  size_type count(const key_type &key) const {
181    return set_.count(key);
182  }
183
184  /// \brief Completely clear the SetVector
185  void clear() {
186    set_.clear();
187    vector_.clear();
188  }
189
190  /// \brief Remove the last element of the SetVector.
191  void pop_back() {
192    assert(!empty() && "Cannot remove an element from an empty SetVector!");
193    set_.erase(back());
194    vector_.pop_back();
195  }
196
197  T LLVM_ATTRIBUTE_UNUSED_RESULT pop_back_val() {
198    T Ret = back();
199    pop_back();
200    return Ret;
201  }
202
203  bool operator==(const SetVector &that) const {
204    return vector_ == that.vector_;
205  }
206
207  bool operator!=(const SetVector &that) const {
208    return vector_ != that.vector_;
209  }
210
211private:
212  /// \brief A wrapper predicate designed for use with std::remove_if.
213  ///
214  /// This predicate wraps a predicate suitable for use with std::remove_if to
215  /// call set_.erase(x) on each element which is slated for removal.
216  template <typename UnaryPredicate>
217  class TestAndEraseFromSet {
218    UnaryPredicate P;
219    set_type &set_;
220
221  public:
222    TestAndEraseFromSet(UnaryPredicate P, set_type &set_) : P(P), set_(set_) {}
223
224    template <typename ArgumentT>
225    bool operator()(const ArgumentT &Arg) {
226      if (P(Arg)) {
227        set_.erase(Arg);
228        return true;
229      }
230      return false;
231    }
232  };
233
234  set_type set_;         ///< The set.
235  vector_type vector_;   ///< The vector.
236};
237
238/// \brief A SetVector that performs no allocations if smaller than
239/// a certain size.
240template <typename T, unsigned N>
241class SmallSetVector : public SetVector<T, SmallVector<T, N>, SmallSet<T, N> > {
242public:
243  SmallSetVector() {}
244
245  /// \brief Initialize a SmallSetVector with a range of elements
246  template<typename It>
247  SmallSetVector(It Start, It End) {
248    this->insert(Start, End);
249  }
250};
251
252} // End llvm namespace
253
254// vim: sw=2 ai
255#endif
256