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