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