1//===- llvm/ADT/UniqueVector.h ----------------------------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#ifndef LLVM_ADT_UNIQUEVECTOR_H
10#define LLVM_ADT_UNIQUEVECTOR_H
11
12#include <cassert>
13#include <cstddef>
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 using VectorType = typename std::vector<T>;
27 using iterator = typename VectorType::iterator;
28 using const_iterator = typename VectorType::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 VectorType Vector;
36
37public:
38 /// insert - Append entry to the vector if it doesn't already exist. Returns
39 /// the entry's index + 1 to be used as a unique ID.
40 unsigned insert(const T &Entry) {
41 // Check if the entry is already in the map.
42 unsigned &Val = Map[Entry];
43
44 // See if entry exists, if so return prior ID.
45 if (Val) return Val;
46
47 // Compute ID for entry.
48 Val = static_cast<unsigned>(Vector.size()) + 1;
49
50 // Insert in vector.
51 Vector.push_back(Entry);
52 return Val;
53 }
54
55 /// idFor - return the ID for an existing entry. Returns 0 if the entry is
56 /// not found.
57 unsigned idFor(const T &Entry) const {
58 // Search for entry in the map.
59 typename std::map<T, unsigned>::const_iterator MI = Map.find(Entry);
60
61 // See if entry exists, if so return ID.
62 if (MI != Map.end()) return MI->second;
63
64 // No luck.
65 return 0;
66 }
67
68 /// operator[] - Returns a reference to the entry with the specified ID.
69 const T &operator[](unsigned ID) const {
70 assert(ID-1 < size() && "ID is 0 or out of range!");
71 return Vector[ID - 1];
72 }
73
74 /// Return an iterator to the start of the vector.
75 iterator begin() { return Vector.begin(); }
76
77 /// Return an iterator to the start of the vector.
78 const_iterator begin() const { return Vector.begin(); }
79
80 /// Return an iterator to the end of the vector.
81 iterator end() { return Vector.end(); }
82
83 /// Return an iterator to the end of the vector.
84 const_iterator end() const { return Vector.end(); }
85
86 /// size - Returns the number of entries in the vector.
87 size_t size() const { return Vector.size(); }
88
89 /// empty - Returns true if the vector is empty.
90 bool empty() const { return Vector.empty(); }
91
92 /// reset - Clears all the entries.
93 void reset() {
94 Map.clear();
95 Vector.resize(0, 0);
96 }
97};
98
99} // end namespace llvm
100
101#endif // LLVM_ADT_UNIQUEVECTOR_H
102