BLI_vector_list.hh

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/* SPDX-FileCopyrightText: 2023 Blender Authors
 *
 * SPDX-License-Identifier: GPL-2.0-or-later */
 
#pragma once
 
#include <algorithm>
 
#include "BLI_vector.hh"
 
namespace blender {

template<typename T, int64_t CapacityStart = 32, int64_t CapacitySoftLimit = 4096>
class VectorList {
 public:
  using UsedVector = Vector<T, 0>;
 
 private:
  Vector<UsedVector> vectors_;
 
 public:
  VectorList()
  {
    this->append_vector();
  }
 
  void append(const T &value)
  {
    this->append_as(value);
  }
 
  void append(T &&value)
  {
    this->append_as(std::move(value));
  }
 
  template<typename ForwardT> void append_as(ForwardT &&value)
  {
    UsedVector &vector = this->ensure_space_for_one();
    vector.append_unchecked_as(std::forward<ForwardT>(value));
  }
 
  UsedVector *begin()
  {
    return vectors_.begin();
  }
 
  UsedVector *end()
  {
    return vectors_.end();
  }
 
  const UsedVector *begin() const
  {
    return vectors_.begin();
  }
 
  const UsedVector *end() const
  {
    return vectors_.end();
  }
 
  T &last()
  {
    return vectors_.last().last();
  }
 
  int64_t size() const
  {
    int64_t result = 0;
    for (const UsedVector &vector : *this) {
      result += vector.size();
    }
    return result;
  }
 
 private:
  UsedVector &ensure_space_for_one()
  {
    UsedVector &vector = vectors_.last();
    if (LIKELY(!vector.is_at_capacity())) {
      return vector;
    }
    this->append_vector();
    return vectors_.last();
  }
 
  void append_vector()
  {
    const int64_t new_vector_capacity = this->get_next_vector_capacity();
    vectors_.append({});
    vectors_.last().reserve(new_vector_capacity);
  }
 
  int64_t get_next_vector_capacity()
  {
    if (vectors_.is_empty()) {
      return CapacityStart;
    }
    return std::min(vectors_.last().capacity() * 2, CapacitySoftLimit);
  }
};
 
}  // namespace blender