1//===- llvm/ADT/IndexedMap.h - An index map implementation ------*- 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// This file implements an indexed map. The index map template takes two
10// types. The first is the mapped type and the second is a functor
11// that maps its argument to a size_t. On instantiation a "null" value
12// can be provided to be used as a "does not exist" indicator in the
13// map. A member function grow() is provided that given the value of
14// the maximally indexed key (the argument of the functor) makes sure
15// the map has enough space for it.
16//
17//===----------------------------------------------------------------------===//
18
19#ifndef LLVM_ADT_INDEXEDMAP_H
20#define LLVM_ADT_INDEXEDMAP_H
21
22#include "llvm/ADT/SmallVector.h"
23#include "llvm/ADT/STLExtras.h"
24#include <cassert>
25
26namespace llvm {
27
28template <typename T, typename ToIndexT = identity<unsigned>>
29  class IndexedMap {
30    using IndexT = typename ToIndexT::argument_type;
31    // Prefer SmallVector with zero inline storage over std::vector. IndexedMaps
32    // can grow very large and SmallVector grows more efficiently as long as T
33    // is trivially copyable.
34    using StorageT = SmallVector<T, 0>;
35
36    StorageT storage_;
37    T nullVal_;
38    ToIndexT toIndex_;
39
40  public:
41    IndexedMap() : nullVal_(T()) {}
42
43    explicit IndexedMap(const T& val) : nullVal_(val) {}
44
45    typename StorageT::reference operator[](IndexT n) {
46      assert(toIndex_(n) < storage_.size() && "index out of bounds!");
47      return storage_[toIndex_(n)];
48    }
49
50    typename StorageT::const_reference operator[](IndexT n) const {
51      assert(toIndex_(n) < storage_.size() && "index out of bounds!");
52      return storage_[toIndex_(n)];
53    }
54
55    void reserve(typename StorageT::size_type s) {
56      storage_.reserve(s);
57    }
58
59    void resize(typename StorageT::size_type s) {
60      storage_.resize(s, nullVal_);
61    }
62
63    void clear() {
64      storage_.clear();
65    }
66
67    void grow(IndexT n) {
68      unsigned NewSize = toIndex_(n) + 1;
69      if (NewSize > storage_.size())
70        resize(NewSize);
71    }
72
73    bool inBounds(IndexT n) const {
74      return toIndex_(n) < storage_.size();
75    }
76
77    typename StorageT::size_type size() const {
78      return storage_.size();
79    }
80  };
81
82} // end namespace llvm
83
84#endif // LLVM_ADT_INDEXEDMAP_H
85