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   using VectorType = typename std::vector<T>;
28   using iterator = typename VectorType::iterator;
29   using const_iterator = typename VectorType::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   VectorType Vector;
37 
38 public:
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.
insert(const T & Entry)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.
idFor(const T & Entry)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   const T &operator[](unsigned ID) const {
71     assert(ID-1 < size() && "ID is 0 or out of range!");
72     return Vector[ID - 1];
73   }
74 
75   /// Return an iterator to the start of the vector.
begin()76   iterator begin() { return Vector.begin(); }
77 
78   /// Return an iterator to the start of the vector.
begin()79   const_iterator begin() const { return Vector.begin(); }
80 
81   /// Return an iterator to the end of the vector.
end()82   iterator end() { return Vector.end(); }
83 
84   /// Return an iterator to the end of the vector.
end()85   const_iterator end() const { return Vector.end(); }
86 
87   /// size - Returns the number of entries in the vector.
size()88   size_t size() const { return Vector.size(); }
89 
90   /// empty - Returns true if the vector is empty.
empty()91   bool empty() const { return Vector.empty(); }
92 
93   /// reset - Clears all the entries.
reset()94   void reset() {
95     Map.clear();
96     Vector.resize(0, 0);
97   }
98 };
99 
100 } // end namespace llvm
101 
102 #endif // LLVM_ADT_UNIQUEVECTOR_H
103