SmallSet.h revision 182907645c9c2da22dba78255f0c8541f5d9f50d 
1//===- llvm/ADT/SmallSet.h - 'Normally small' sets --------------*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file was developed by Chris Lattner and is distributed under
6// the University of Illinois Open Source License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file defines the SmallSet class.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_ADT_SMALLSET_H
15#define LLVM_ADT_SMALLSET_H
16
17#include "llvm/ADT/SmallVector.h"
18
19namespace llvm {
20
21/// SmallSet - This maintains a set of unique values, optimizing for the case
22/// when the set is small (less than N).  In this case, the set can be
23/// maintained with no mallocs.
24///
25/// Note that this set does not guarantee that the elements in the set will be
26/// ordered.
27template <typename T, unsigned N>
28class SmallSet {
29  SmallVector<T, N> Vector;
30  typedef typename SmallVector<T, N>::iterator mutable_iterator;
31public:
32  SmallSet() {}
33
34  // Support iteration.
35  typedef typename SmallVector<T, N>::const_iterator iterator;
36  typedef typename SmallVector<T, N>::const_iterator const_iterator;
37
38  iterator begin() const { return Vector.begin(); }
39  iterator end() const { return Vector.end(); }
40
41  bool empty() const { return Vector.empty(); }
42  unsigned size() const { return Vector.size(); }
43
44  iterator find(const T &V) const {
45    for (iterator I = begin(), E = end(); I != E; ++I)
46      if (*I == V)
47        return I;
48    return end();
49  }
50
51  /// count - Return true if the element is in the set.
52  unsigned count(const T &V) const {
53    // Since the collection is small, just do a linear search.
54    return find(V) != end();
55  }
56
57  /// insert - Insert an element into the set if it isn't already there.
58  std::pair<iterator,bool> insert(const T &V) {
59    iterator I = find(V);
60    if (I == end())    // Don't reinsert if it already exists.
61      return std::make_pair(I, false);
62    Vector.push_back(V);
63    return std::make_pair(end()-1, true);
64  }
65
66  void erase(const T &V) {
67    for (mutable_iterator I = Vector.begin(), E = Vector.end(); I != E; ++I)
68      if (*I == V) {
69        Vector.erase(I);
70        return;
71      }
72  }
73
74  void clear() {
75    Vector.clear();
76  }
77
78};
79
80
81} // end namespace llvm
82
83#endif
84