kc3-lang/angle/src/common/FixedVector.h

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• Hash : 2d28e33f
  Author :
  Date : 2025-08-28T23:50:51
  

  Avoid some large copies in range-based for-loops
  
  Avoid copies as detected some time ago by a clang compiler plugin,
  typically this indicates a missing & in the range-based for-loop.
  
  -- For the vector initialize code, see https://godbolt.org/z/4PWseve5P
     as to why I think a copy-assign is more efficient than a copy-
     construct followed by a move-assign.
  
  Bug: b/415953694
  Change-Id: I2cf9f713277d811127834235507ee075c4a72956
  Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/6898417
  Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>
  Reviewed-by: Geoff Lang <geofflang@chromium.org>
  Commit-Queue: Geoff Lang <geofflang@chromium.org>
  Auto-Submit: Tom Sepez <tsepez@chromium.org>
  

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• src/common/FixedVector.h

• //
  // Copyright 2018 The ANGLE Project Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  //
  // FixedVector.h:
  //   A vector class with a maximum size and fixed storage.
  //
  
  #ifndef COMMON_FIXEDVECTOR_H_
  #define COMMON_FIXEDVECTOR_H_
  
  #include "common/debug.h"
  
  #include <algorithm>
  #include <array>
  #include <initializer_list>
  
  namespace angle
  {
  template <class T, size_t N, class Storage = std::array<T, N>>
  class FixedVector final
  {
    public:
      using value_type             = typename Storage::value_type;
      using size_type              = typename Storage::size_type;
      using reference              = typename Storage::reference;
      using const_reference        = typename Storage::const_reference;
      using pointer                = typename Storage::pointer;
      using const_pointer          = typename Storage::const_pointer;
      using iterator               = typename Storage::iterator;
      using const_iterator         = typename Storage::const_iterator;
      using reverse_iterator       = typename Storage::reverse_iterator;
      using const_reverse_iterator = typename Storage::const_reverse_iterator;
  
      FixedVector();
      FixedVector(size_type count, const value_type &value);
      FixedVector(size_type count);
  
      FixedVector(const FixedVector<T, N, Storage> &other);
      FixedVector(FixedVector<T, N, Storage> &&other);
      FixedVector(std::initializer_list<value_type> init);
  
      FixedVector<T, N, Storage> &operator=(const FixedVector<T, N, Storage> &other);
      FixedVector<T, N, Storage> &operator=(FixedVector<T, N, Storage> &&other);
      FixedVector<T, N, Storage> &operator=(std::initializer_list<value_type> init);
  
      // Makes class trivially destructible.
      ~FixedVector() = default;
  
      reference at(size_type pos);
      const_reference at(size_type pos) const;
  
      reference operator[](size_type pos);
      const_reference operator[](size_type pos) const;
  
      pointer data();
      const_pointer data() const;
  
      iterator begin();
      const_iterator begin() const;
  
      iterator end();
      const_iterator end() const;
  
      bool empty() const;
      size_type size() const;
      static constexpr size_type max_size();
  
      void clear();
  
      void push_back(const value_type &value);
      void push_back(value_type &&value);
  
      template <class... Args>
      void emplace_back(Args &&...args);
  
      void pop_back();
      reference back();
      const_reference back() const;
  
      void swap(FixedVector<T, N, Storage> &other);
  
      void resize(size_type count);
      void resize(size_type count, const value_type &value);
  
      bool full() const;
  
    private:
      void assign_from_initializer_list(std::initializer_list<value_type> init);
  
      Storage mStorage;
      size_type mSize = 0;
  };
  
  template <class T, size_t N, class Storage>
  bool operator==(const FixedVector<T, N, Storage> &a, const FixedVector<T, N, Storage> &b)
  {
      return a.size() == b.size() && std::equal(a.begin(), a.end(), b.begin());
  }
  
  template <class T, size_t N, class Storage>
  bool operator!=(const FixedVector<T, N, Storage> &a, const FixedVector<T, N, Storage> &b)
  {
      return !(a == b);
  }
  
  template <class T, size_t N, class Storage>
  FixedVector<T, N, Storage>::FixedVector() = default;
  
  template <class T, size_t N, class Storage>
  FixedVector<T, N, Storage>::FixedVector(size_type count, const value_type &value) : mSize(count)
  {
      ASSERT(count <= N);
      std::fill(mStorage.begin(), mStorage.begin() + count, value);
  }
  
  template <class T, size_t N, class Storage>
  FixedVector<T, N, Storage>::FixedVector(size_type count) : mSize(count)
  {
      ASSERT(count <= N);
  }
  
  template <class T, size_t N, class Storage>
  FixedVector<T, N, Storage>::FixedVector(const FixedVector<T, N, Storage> &other) = default;
  
  template <class T, size_t N, class Storage>
  FixedVector<T, N, Storage>::FixedVector(FixedVector<T, N, Storage> &&other)
      : mStorage(std::move(other.mStorage)), mSize(other.mSize)
  {
      other.mSize = 0;
  }
  
  template <class T, size_t N, class Storage>
  FixedVector<T, N, Storage>::FixedVector(std::initializer_list<value_type> init)
  {
      ASSERT(init.size() <= N);
      assign_from_initializer_list(init);
  }
  
  template <class T, size_t N, class Storage>
  FixedVector<T, N, Storage> &FixedVector<T, N, Storage>::operator=(
      const FixedVector<T, N, Storage> &other) = default;
  
  template <class T, size_t N, class Storage>
  FixedVector<T, N, Storage> &FixedVector<T, N, Storage>::operator=(
      FixedVector<T, N, Storage> &&other)
  {
      mStorage    = std::move(other.mStorage);
      mSize       = other.mSize;
      other.mSize = 0;
      return *this;
  }
  
  template <class T, size_t N, class Storage>
  FixedVector<T, N, Storage> &FixedVector<T, N, Storage>::operator=(
      std::initializer_list<value_type> init)
  {
      clear();
      ASSERT(init.size() <= N);
      assign_from_initializer_list(init);
      return *this;
  }
  
  template <class T, size_t N, class Storage>
  typename FixedVector<T, N, Storage>::reference FixedVector<T, N, Storage>::at(size_type pos)
  {
      ASSERT(pos < mSize);
      return mStorage.at(pos);
  }
  
  template <class T, size_t N, class Storage>
  typename FixedVector<T, N, Storage>::const_reference FixedVector<T, N, Storage>::at(
      size_type pos) const
  {
      ASSERT(pos < mSize);
      return mStorage.at(pos);
  }
  
  template <class T, size_t N, class Storage>
  typename FixedVector<T, N, Storage>::reference FixedVector<T, N, Storage>::operator[](size_type pos)
  {
      ASSERT(pos < mSize);
      return mStorage[pos];
  }
  
  template <class T, size_t N, class Storage>
  typename FixedVector<T, N, Storage>::const_reference FixedVector<T, N, Storage>::operator[](
      size_type pos) const
  {
      ASSERT(pos < mSize);
      return mStorage[pos];
  }
  
  template <class T, size_t N, class Storage>
  typename FixedVector<T, N, Storage>::const_pointer angle::FixedVector<T, N, Storage>::data() const
  {
      return mStorage.data();
  }
  
  template <class T, size_t N, class Storage>
  typename FixedVector<T, N, Storage>::pointer angle::FixedVector<T, N, Storage>::data()
  {
      return mStorage.data();
  }
  
  template <class T, size_t N, class Storage>
  typename FixedVector<T, N, Storage>::iterator FixedVector<T, N, Storage>::begin()
  {
      return mStorage.begin();
  }
  
  template <class T, size_t N, class Storage>
  typename FixedVector<T, N, Storage>::const_iterator FixedVector<T, N, Storage>::begin() const
  {
      return mStorage.begin();
  }
  
  template <class T, size_t N, class Storage>
  typename FixedVector<T, N, Storage>::iterator FixedVector<T, N, Storage>::end()
  {
      return mStorage.begin() + mSize;
  }
  
  template <class T, size_t N, class Storage>
  typename FixedVector<T, N, Storage>::const_iterator FixedVector<T, N, Storage>::end() const
  {
      return mStorage.begin() + mSize;
  }
  
  template <class T, size_t N, class Storage>
  bool FixedVector<T, N, Storage>::empty() const
  {
      return mSize == 0;
  }
  
  template <class T, size_t N, class Storage>
  typename FixedVector<T, N, Storage>::size_type FixedVector<T, N, Storage>::size() const
  {
      return mSize;
  }
  
  template <class T, size_t N, class Storage>
  constexpr typename FixedVector<T, N, Storage>::size_type FixedVector<T, N, Storage>::max_size()
  {
      return N;
  }
  
  template <class T, size_t N, class Storage>
  void FixedVector<T, N, Storage>::clear()
  {
      resize(0);
  }
  
  template <class T, size_t N, class Storage>
  void FixedVector<T, N, Storage>::push_back(const value_type &value)
  {
      ASSERT(mSize < N);
      mStorage[mSize] = value;
      mSize++;
  }
  
  template <class T, size_t N, class Storage>
  void FixedVector<T, N, Storage>::push_back(value_type &&value)
  {
      ASSERT(mSize < N);
      mStorage[mSize] = std::move(value);
      mSize++;
  }
  
  template <class T, size_t N, class Storage>
  template <class... Args>
  void FixedVector<T, N, Storage>::emplace_back(Args &&...args)
  {
      ASSERT(mSize < N);
      new (&mStorage[mSize]) T{std::forward<Args>(args)...};
      mSize++;
  }
  
  template <class T, size_t N, class Storage>
  void FixedVector<T, N, Storage>::pop_back()
  {
      ASSERT(mSize > 0);
      mSize--;
  }
  
  template <class T, size_t N, class Storage>
  typename FixedVector<T, N, Storage>::reference FixedVector<T, N, Storage>::back()
  {
      ASSERT(mSize > 0);
      return mStorage[mSize - 1];
  }
  
  template <class T, size_t N, class Storage>
  typename FixedVector<T, N, Storage>::const_reference FixedVector<T, N, Storage>::back() const
  {
      ASSERT(mSize > 0);
      return mStorage[mSize - 1];
  }
  
  template <class T, size_t N, class Storage>
  void FixedVector<T, N, Storage>::swap(FixedVector<T, N, Storage> &other)
  {
      std::swap(mSize, other.mSize);
      std::swap(mStorage, other.mStorage);
  }
  
  template <class T, size_t N, class Storage>
  void FixedVector<T, N, Storage>::resize(size_type count)
  {
      ASSERT(count <= N);
      while (mSize > count)
      {
          mSize--;
          mStorage[mSize] = value_type();
      }
      while (mSize < count)
      {
          mStorage[mSize] = value_type();
          mSize++;
      }
  }
  
  template <class T, size_t N, class Storage>
  void FixedVector<T, N, Storage>::resize(size_type count, const value_type &value)
  {
      ASSERT(count <= N);
      while (mSize > count)
      {
          mSize--;
          mStorage[mSize] = value_type();
      }
      while (mSize < count)
      {
          mStorage[mSize] = value;
          mSize++;
      }
  }
  
  template <class T, size_t N, class Storage>
  void FixedVector<T, N, Storage>::assign_from_initializer_list(
      std::initializer_list<value_type> init)
  {
      for (const auto &element : init)
      {
          mStorage[mSize] = element;
          mSize++;
      }
  }
  
  template <class T, size_t N, class Storage>
  bool FixedVector<T, N, Storage>::full() const
  {
      return (mSize == N);
  }
  }  // namespace angle
  
  #endif  // COMMON_FIXEDVECTOR_H_
  

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