1//===- llvm/ADT/IndexedMap.h - An index map implementation ------*- 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// This file implements an indexed map. The index 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_INDEXEDMAP_H
21#define LLVM_ADT_INDEXEDMAP_H
22
23#include "llvm/ADT/SmallVector.h"
24#include "llvm/ADT/STLExtras.h"
25#include <cassert>
26
27namespace llvm {
28
29template <typename T, typename ToIndexT = identity<unsigned>>
30  class IndexedMap {
31    using IndexT = typename ToIndexT::argument_type;
32    // Prefer SmallVector with zero inline storage over std::vector. IndexedMaps
33    // can grow very large and SmallVector grows more efficiently as long as T
34    // is trivially copyable.
35    using StorageT = SmallVector<T, 0>;
36
37    StorageT storage_;
38    T nullVal_;
39    ToIndexT toIndex_;
40
41  public:
42    IndexedMap() : nullVal_(T()) {}
43
44    explicit IndexedMap(const T& val) : nullVal_(val) {}
45
46    typename StorageT::reference operator[](IndexT n) {
47      assert(toIndex_(n) < storage_.size() && "index out of bounds!");
48      return storage_[toIndex_(n)];
49    }
50
51    typename StorageT::const_reference operator[](IndexT n) const {
52      assert(toIndex_(n) < storage_.size() && "index out of bounds!");
53      return storage_[toIndex_(n)];
54    }
55
56    void reserve(typename StorageT::size_type s) {
57      storage_.reserve(s);
58    }
59
60    void resize(typename StorageT::size_type s) {
61      storage_.resize(s, nullVal_);
62    }
63
64    void clear() {
65      storage_.clear();
66    }
67
68    void grow(IndexT n) {
69      unsigned NewSize = toIndex_(n) + 1;
70      if (NewSize > storage_.size())
71        resize(NewSize);
72    }
73
74    bool inBounds(IndexT n) const {
75      return toIndex_(n) < storage_.size();
76    }
77
78    typename StorageT::size_type size() const {
79      return storage_.size();
80    }
81  };
82
83} // end namespace llvm
84
85#endif // LLVM_ADT_INDEXEDMAP_H
86