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