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(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