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 <cstddef>
15 #include <map>
16 #include <vector>
17 
18 namespace llvm {
19 
20 //===----------------------------------------------------------------------===//
21 /// UniqueVector - This class produces a sequential ID number (base 1) for each
22 /// unique entry that is added.  T is the type of entries in the vector. This
23 /// class should have an implementation of operator== and of operator<.
24 /// Entries can be fetched using operator[] with the entry ID.
25 template<class T> class UniqueVector {
26 public:
27   typedef typename std::vector<T> VectorType;
28   typedef typename VectorType::iterator iterator;
29   typedef typename VectorType::const_iterator const_iterator;
30 
31 private:
32   // Map - Used to handle the correspondence of entry to ID.
33   std::map<T, unsigned> Map;
34 
35   // Vector - ID ordered vector of entries. Entries can be indexed by ID - 1.
36   //
37   VectorType Vector;
38 
39 public:
40   /// insert - Append entry to the vector if it doesn't already exist.  Returns
41   /// the entry's index + 1 to be used as a unique ID.
insert(const T & Entry)42   unsigned insert(const T &Entry) {
43     // Check if the entry is already in the map.
44     unsigned &Val = Map[Entry];
45 
46     // See if entry exists, if so return prior ID.
47     if (Val) return Val;
48 
49     // Compute ID for entry.
50     Val = static_cast<unsigned>(Vector.size()) + 1;
51 
52     // Insert in vector.
53     Vector.push_back(Entry);
54     return Val;
55   }
56 
57   /// idFor - return the ID for an existing entry.  Returns 0 if the entry is
58   /// not found.
idFor(const T & Entry)59   unsigned idFor(const T &Entry) const {
60     // Search for entry in the map.
61     typename std::map<T, unsigned>::const_iterator MI = Map.find(Entry);
62 
63     // See if entry exists, if so return ID.
64     if (MI != Map.end()) return MI->second;
65 
66     // No luck.
67     return 0;
68   }
69 
70   /// operator[] - Returns a reference to the entry with the specified ID.
71   ///
72   const T &operator[](unsigned ID) const {
73     assert(ID-1 < size() && "ID is 0 or out of range!");
74     return Vector[ID - 1];
75   }
76 
77   /// \brief Return an iterator to the start of the vector.
begin()78   iterator begin() { return Vector.begin(); }
79 
80   /// \brief Return an iterator to the start of the vector.
begin()81   const_iterator begin() const { return Vector.begin(); }
82 
83   /// \brief Return an iterator to the end of the vector.
end()84   iterator end() { return Vector.end(); }
85 
86   /// \brief Return an iterator to the end of the vector.
end()87   const_iterator end() const { return Vector.end(); }
88 
89   /// size - Returns the number of entries in the vector.
90   ///
size()91   size_t size() const { return Vector.size(); }
92 
93   /// empty - Returns true if the vector is empty.
94   ///
empty()95   bool empty() const { return Vector.empty(); }
96 
97   /// reset - Clears all the entries.
98   ///
reset()99   void reset() {
100     Map.clear();
101     Vector.resize(0, 0);
102   }
103 };
104 
105 } // End of namespace llvm
106 
107 #endif // LLVM_ADT_UNIQUEVECTOR_H
108