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