SmallSet.h revision 89502f086901acf6210b711f01726863f8445469 
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  /// count - Return true if the element is in the set.
45  unsigned count(const T &V) const {
46    // Since the collection is small, just do a linear search.
47    for (iterator I = begin(), E = end(); I != E; ++I)
48      if (*I == V)
49        return 1;
50    return 0;
51  }
52
53  /// insert - Insert an element into the set if it isn't already there.
54  void insert(const T &V) {
55    if (count(V)) return;   // Don't reinsert if it already exists.
56    Vector.push_back(V);
57  }
58
59  void erase(const T &V) {
60    for (mutable_iterator I = Vector.begin(), E = Vector.end(); I != E; ++I)
61      if (*I == V) {
62        Vector.erase(I);
63        return;
64      }
65  }
66
67  void clear() {
68    Vector.clear();
69  }
70
71};
72
73
74} // end namespace llvm
75
76#endif
77