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/// \file
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 "llvm/ADT/identity.h"
26#include <cassert>
27
28namespace llvm {
29
30template <typename T, typename ToIndexT = identity<unsigned>>
31 class IndexedMap {
32 using IndexT = typename ToIndexT::argument_type;
33 // Prefer SmallVector with zero inline storage over std::vector. IndexedMaps
34 // can grow very large and SmallVector grows more efficiently as long as T
35 // is trivially copyable.
36 using StorageT = SmallVector<T, 0>;
37
38 StorageT storage_;
39 T nullVal_;
40 ToIndexT toIndex_;
41
42 public:
43 IndexedMap() : nullVal_(T()) {}
44
45 explicit IndexedMap(const T& val) : nullVal_(val) {}
46
47 typename StorageT::reference operator[](IndexT n) {
48 assert(toIndex_(n) < storage_.size() && "index out of bounds!");
49 return storage_[toIndex_(n)];
50 }
51
52 typename StorageT::const_reference operator[](IndexT n) const {
53 assert(toIndex_(n) < storage_.size() && "index out of bounds!");
54 return storage_[toIndex_(n)];
55 }
56
57 void reserve(typename StorageT::size_type s) {
58 storage_.reserve(s);
59 }
60
61 void resize(typename StorageT::size_type s) {
62 storage_.resize(s, nullVal_);
63 }
64
65 void clear() {
66 storage_.clear();
67 }
68
69 void grow(IndexT n) {
70 unsigned NewSize = toIndex_(n) + 1;
71 if (NewSize > storage_.size())
72 resize(s: NewSize);
73 }
74
75 bool inBounds(IndexT n) const {
76 return toIndex_(n) < storage_.size();
77 }
78
79 typename StorageT::size_type size() const {
80 return storage_.size();
81 }
82 };
83
84} // end namespace llvm
85
86#endif // LLVM_ADT_INDEXEDMAP_H
87

source code of llvm/include/llvm/ADT/IndexedMap.h