DenseMap.h revision 8018a665b2fa8250f12e079b19459c662cdd27f0 
1//===- llvm/ADT/DenseMap.h - A dense map implmentation ----------*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file was developed by the LLVM research group and is distributed under
6// the University of Illinois Open Source License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file implements a dense map. A dense map template takes two
11// types. The first is the mapped type and the second is a functor
12// that maps its argument to a size_t. On instantiation a "null" value
13// can be provided to be used as a "does not exist" indicator in the
14// map. A member function grow() is provided that given the value of
15// the maximally indexed key (the argument of the functor) makes sure
16// the map has enough space for it.
17//
18//===----------------------------------------------------------------------===//
19
20#ifndef LLVM_ADT_DENSEMAP_H
21#define LLVM_ADT_DENSEMAP_H
22
23#include <functional>
24#include <vector>
25#include <cassert>
26
27namespace llvm {
28
29  struct IdentityFunctor : std::unary_function<unsigned, unsigned> {
30    unsigned operator()(unsigned Index) const {
31      return Index;
32    }
33  };
34
35  template <typename T, typename ToIndexT = IdentityFunctor>
36  class DenseMap {
37    typedef typename ToIndexT::argument_type IndexT;
38    typedef std::vector<T> StorageT;
39    StorageT storage_;
40    T nullVal_;
41    ToIndexT toIndex_;
42
43  public:
44    DenseMap() : nullVal_(T()) { }
45
46    explicit DenseMap(const T& val) : nullVal_(val) { }
47
48    typename StorageT::reference operator[](IndexT n) {
49      assert(toIndex_(n) < storage_.size() && "index out of bounds!");
50      return storage_[toIndex_(n)];
51    }
52
53    typename StorageT::const_reference operator[](IndexT n) const {
54      assert(toIndex_(n) < storage_.size() && "index out of bounds!");
55      return storage_[toIndex_(n)];
56    }
57
58    void clear() {
59      storage_.clear();
60    }
61
62    void grow(IndexT n) {
63      unsigned NewSize = toIndex_(n) + 1;
64      if (NewSize > storage_.size())
65        storage_.resize(NewSize, nullVal_);
66    }
67
68    typename StorageT::size_type size() const {
69      return storage_.size();
70    }
71  };
72
73} // End llvm namespace
74
75#endif
76