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 {
25private:
26  // Map - Used to handle the correspondence of entry to ID.
27  std::map<T, unsigned> Map;
28
29  // Vector - ID ordered vector of entries. Entries can be indexed by ID - 1.
30  //
31  std::vector<T> Vector;
32
33public:
34  /// insert - Append entry to the vector if it doesn't already exist.  Returns
35  /// the entry's index + 1 to be used as a unique ID.
36  unsigned insert(const T &Entry) {
37    // Check if the entry is already in the map.
38    unsigned &Val = Map[Entry];
39
40    // See if entry exists, if so return prior ID.
41    if (Val) return Val;
42
43    // Compute ID for entry.
44    Val = static_cast<unsigned>(Vector.size()) + 1;
45
46    // Insert in vector.
47    Vector.push_back(Entry);
48    return Val;
49  }
50
51  /// idFor - return the ID for an existing entry.  Returns 0 if the entry is
52  /// not found.
53  unsigned idFor(const T &Entry) const {
54    // Search for entry in the map.
55    typename std::map<T, unsigned>::const_iterator MI = Map.find(Entry);
56
57    // See if entry exists, if so return ID.
58    if (MI != Map.end()) return MI->second;
59
60    // No luck.
61    return 0;
62  }
63
64  /// operator[] - Returns a reference to the entry with the specified ID.
65  ///
66  const T &operator[](unsigned ID) const {
67    assert(ID-1 < size() && "ID is 0 or out of range!");
68    return Vector[ID - 1];
69  }
70
71  /// size - Returns the number of entries in the vector.
72  ///
73  size_t size() const { return Vector.size(); }
74
75  /// empty - Returns true if the vector is empty.
76  ///
77  bool empty() const { return Vector.empty(); }
78
79  /// reset - Clears all the entries.
80  ///
81  void reset() {
82    Map.clear();
83    Vector.resize(0, 0);
84  }
85};
86
87} // End of namespace llvm
88
89#endif // LLVM_ADT_UNIQUEVECTOR_H
90