85 lines
2.6 KiB
C++
85 lines
2.6 KiB
C++
//===- llvm/ADT/IndexedMap.h - An index map implementation ------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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///
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/// \file
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/// This file implements an indexed map. The index map template takes two
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/// types. The first is the mapped type and the second is a functor
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/// that maps its argument to a size_t. On instantiation a "null" value
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/// can be provided to be used as a "does not exist" indicator in the
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/// map. A member function grow() is provided that given the value of
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/// the maximally indexed key (the argument of the functor) makes sure
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/// the map has enough space for it.
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///
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_ADT_INDEXEDMAP_H
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#define LLVM_ADT_INDEXEDMAP_H
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#include "llvm/ADT/STLExtras.h"
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#include "llvm/ADT/SmallVector.h"
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#include <cassert>
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namespace llvm {
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namespace detail {
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template <class Ty> struct IdentityIndex {
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using argument_type = Ty;
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Ty &operator()(Ty &self) const { return self; }
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const Ty &operator()(const Ty &self) const { return self; }
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};
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} // namespace detail
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template <typename T, typename ToIndexT = detail::IdentityIndex<unsigned>>
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class IndexedMap {
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using IndexT = typename ToIndexT::argument_type;
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// Prefer SmallVector with zero inline storage over std::vector. IndexedMaps
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// can grow very large and SmallVector grows more efficiently as long as T
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// is trivially copyable.
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using StorageT = SmallVector<T, 0>;
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StorageT Storage;
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T NullVal = T();
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ToIndexT ToIndex;
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public:
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IndexedMap() = default;
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explicit IndexedMap(const T &Val) : NullVal(Val) {}
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typename StorageT::reference operator[](IndexT N) {
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assert(ToIndex(N) < Storage.size() && "index out of bounds!");
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return Storage[ToIndex(N)];
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}
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typename StorageT::const_reference operator[](IndexT N) const {
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assert(ToIndex(N) < Storage.size() && "index out of bounds!");
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return Storage[ToIndex(N)];
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}
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void reserve(typename StorageT::size_type S) { Storage.reserve(S); }
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void resize(typename StorageT::size_type S) { Storage.resize(S, NullVal); }
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void clear() { Storage.clear(); }
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void grow(IndexT N) {
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unsigned NewSize = ToIndex(N) + 1;
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if (NewSize > Storage.size())
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resize(NewSize);
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}
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bool inBounds(IndexT N) const { return ToIndex(N) < Storage.size(); }
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typename StorageT::size_type size() const { return Storage.size(); }
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};
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} // namespace llvm
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#endif // LLVM_ADT_INDEXEDMAP_H
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