string_inplace.hpp

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/*
 * This file is part of OpenTTD.
 * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
 * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <https://www.gnu.org/licenses/old-licenses/gpl-2.0>.
 */

 
#ifndef STRING_INPLACE_HPP
#define STRING_INPLACE_HPP
 
#include "string_builder.hpp"
#include "string_consumer.hpp"

class InPlaceBuilder final : public BaseStringBuilder {
  std::span<char> dest; 
  size_type position = 0; 
  const StringConsumer &consumer; 
 
  friend class InPlaceReplacement;

  explicit InPlaceBuilder(std::span<char> dest, const StringConsumer &consumer) : dest(dest), consumer(consumer) {}

  InPlaceBuilder(const InPlaceBuilder &src, const StringConsumer &consumer) : dest(src.dest), position(src.position), consumer(consumer) {}

  void AssignBuffer(const InPlaceBuilder &src) { this->dest = src.dest; this->position = src.position; }
public:
  InPlaceBuilder(const InPlaceBuilder &) = delete;
  InPlaceBuilder& operator=(const InPlaceBuilder &) = delete;

  [[nodiscard]] bool AnyBytesWritten() const noexcept { return this->position != 0; }
  [[nodiscard]] size_type GetBytesWritten() const noexcept { return this->position; }
  [[nodiscard]] std::string_view GetWrittenData() const noexcept { return {this->dest.data(), this->position}; }
 
  [[nodiscard]] bool AnyBytesUnused() const noexcept;
  [[nodiscard]] size_type GetBytesUnused() const noexcept;
 
  void PutBuffer(std::span<const char> str) override;

  class back_insert_iterator {
    InPlaceBuilder *parent = nullptr; 
  public:
    using value_type = void; 
    using difference_type = void; 
    using iterator_category = std::output_iterator_tag; 
    using pointer = void; 
    using reference = void; 

    back_insert_iterator(InPlaceBuilder &parent) : parent(&parent) {}
 
    back_insert_iterator &operator++() { return *this; }
    back_insert_iterator operator++(int) { return *this; }
    back_insert_iterator &operator*() { return *this; }
 
    back_insert_iterator &operator=(char value)
    {
      this->parent->PutChar(value);
      return *this;
    }
  };

  back_insert_iterator back_inserter()
  {
    return back_insert_iterator(*this);
  }
};

class InPlaceReplacement {
public:
  StringConsumer consumer; 
  InPlaceBuilder builder; 
 
public:
  InPlaceReplacement(std::span<char> buffer);
  InPlaceReplacement(const InPlaceReplacement &src);
  InPlaceReplacement& operator=(const InPlaceReplacement &src);
};
 
#endif /* STRING_INPLACE_HPP */