1//===-- llvm/ADT/UniqueVector.h ---------------------------------*- 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#ifndef LLVM_ADT_UNIQUEVECTOR_H
11#define LLVM_ADT_UNIQUEVECTOR_H
12
13#include <cassert>
14#include <map>
15#include <vector>
16
17namespace llvm {
18
19//===----------------------------------------------------------------------===//
20/// UniqueVector - This class produces a sequential ID number (base 1) for each
21/// unique entry that is added.  T is the type of entries in the vector. This
22/// class should have an implementation of operator== and of operator<.
23/// Entries can be fetched using operator[] with the entry ID.
24template<class T> class UniqueVector {
25public:
26  typedef typename std::vector<T> VectorType;
27  typedef typename VectorType::iterator iterator;
28  typedef typename VectorType::const_iterator const_iterator;
29
30private:
31  // Map - Used to handle the correspondence of entry to ID.
32  std::map<T, unsigned> Map;
33
34  // Vector - ID ordered vector of entries. Entries can be indexed by ID - 1.
35  //
36  VectorType Vector;
37
38public:
39  /// insert - Append entry to the vector if it doesn't already exist.  Returns
40  /// the entry's index + 1 to be used as a unique ID.
41  unsigned insert(const T &Entry) {
42    // Check if the entry is already in the map.
43    unsigned &Val = Map[Entry];
44
45    // See if entry exists, if so return prior ID.
46    if (Val) return Val;
47
48    // Compute ID for entry.
49    Val = static_cast<unsigned>(Vector.size()) + 1;
50
51    // Insert in vector.
52    Vector.push_back(Entry);
53    return Val;
54  }
55
56  /// idFor - return the ID for an existing entry.  Returns 0 if the entry is
57  /// not found.
58  unsigned idFor(const T &Entry) const {
59    // Search for entry in the map.
60    typename std::map<T, unsigned>::const_iterator MI = Map.find(Entry);
61
62    // See if entry exists, if so return ID.
63    if (MI != Map.end()) return MI->second;
64
65    // No luck.
66    return 0;
67  }
68
69  /// operator[] - Returns a reference to the entry with the specified ID.
70  ///
71  const T &operator[](unsigned ID) const {
72    assert(ID-1 < size() && "ID is 0 or out of range!");
73    return Vector[ID - 1];
74  }
75
76  /// \brief Return an iterator to the start of the vector.
77  iterator begin() { return Vector.begin(); }
78
79  /// \brief Return an iterator to the start of the vector.
80  const_iterator begin() const { return Vector.begin(); }
81
82  /// \brief Return an iterator to the end of the vector.
83  iterator end() { return Vector.end(); }
84
85  /// \brief Return an iterator to the end of the vector.
86  const_iterator end() const { return Vector.end(); }
87
88  /// size - Returns the number of entries in the vector.
89  ///
90  size_t size() const { return Vector.size(); }
91
92  /// empty - Returns true if the vector is empty.
93  ///
94  bool empty() const { return Vector.empty(); }
95
96  /// reset - Clears all the entries.
97  ///
98  void reset() {
99    Map.clear();
100    Vector.resize(0, 0);
101  }
102};
103
104} // End of namespace llvm
105
106#endif // LLVM_ADT_UNIQUEVECTOR_H
107