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1 //===- BlotMapVector.h - A MapVector with the blot operation -*- 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 #include "llvm/ADT/DenseMap.h"
11 #include <vector>
12 #include <algorithm>
13 
14 namespace llvm {
15 /// \brief An associative container with fast insertion-order (deterministic)
16 /// iteration over its elements. Plus the special blot operation.
17 template <class KeyT, class ValueT> class BlotMapVector {
18   /// Map keys to indices in Vector.
19   typedef DenseMap<KeyT, size_t> MapTy;
20   MapTy Map;
21 
22   typedef std::vector<std::pair<KeyT, ValueT>> VectorTy;
23   /// Keys and values.
24   VectorTy Vector;
25 
26 public:
27   typedef typename VectorTy::iterator iterator;
28   typedef typename VectorTy::const_iterator const_iterator;
begin()29   iterator begin() { return Vector.begin(); }
end()30   iterator end() { return Vector.end(); }
begin()31   const_iterator begin() const { return Vector.begin(); }
end()32   const_iterator end() const { return Vector.end(); }
33 
34 #ifdef EXPENSIVE_CHECKS
~BlotMapVector()35   ~BlotMapVector() {
36     assert(Vector.size() >= Map.size()); // May differ due to blotting.
37     for (typename MapTy::const_iterator I = Map.begin(), E = Map.end(); I != E;
38          ++I) {
39       assert(I->second < Vector.size());
40       assert(Vector[I->second].first == I->first);
41     }
42     for (typename VectorTy::const_iterator I = Vector.begin(), E = Vector.end();
43          I != E; ++I)
44       assert(!I->first || (Map.count(I->first) &&
45                            Map[I->first] == size_t(I - Vector.begin())));
46   }
47 #endif
48 
49   ValueT &operator[](const KeyT &Arg) {
50     std::pair<typename MapTy::iterator, bool> Pair =
51         Map.insert(std::make_pair(Arg, size_t(0)));
52     if (Pair.second) {
53       size_t Num = Vector.size();
54       Pair.first->second = Num;
55       Vector.push_back(std::make_pair(Arg, ValueT()));
56       return Vector[Num].second;
57     }
58     return Vector[Pair.first->second].second;
59   }
60 
insert(const std::pair<KeyT,ValueT> & InsertPair)61   std::pair<iterator, bool> insert(const std::pair<KeyT, ValueT> &InsertPair) {
62     std::pair<typename MapTy::iterator, bool> Pair =
63         Map.insert(std::make_pair(InsertPair.first, size_t(0)));
64     if (Pair.second) {
65       size_t Num = Vector.size();
66       Pair.first->second = Num;
67       Vector.push_back(InsertPair);
68       return std::make_pair(Vector.begin() + Num, true);
69     }
70     return std::make_pair(Vector.begin() + Pair.first->second, false);
71   }
72 
find(const KeyT & Key)73   iterator find(const KeyT &Key) {
74     typename MapTy::iterator It = Map.find(Key);
75     if (It == Map.end())
76       return Vector.end();
77     return Vector.begin() + It->second;
78   }
79 
find(const KeyT & Key)80   const_iterator find(const KeyT &Key) const {
81     typename MapTy::const_iterator It = Map.find(Key);
82     if (It == Map.end())
83       return Vector.end();
84     return Vector.begin() + It->second;
85   }
86 
87   /// This is similar to erase, but instead of removing the element from the
88   /// vector, it just zeros out the key in the vector. This leaves iterators
89   /// intact, but clients must be prepared for zeroed-out keys when iterating.
blot(const KeyT & Key)90   void blot(const KeyT &Key) {
91     typename MapTy::iterator It = Map.find(Key);
92     if (It == Map.end())
93       return;
94     Vector[It->second].first = KeyT();
95     Map.erase(It);
96   }
97 
clear()98   void clear() {
99     Map.clear();
100     Vector.clear();
101   }
102 
empty()103   bool empty() const {
104     assert(Map.empty() == Vector.empty());
105     return Map.empty();
106   }
107 };
108 } //
109