json_writer.hpp

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// SPDX-FileCopyrightText: 2006-2026 Knut Reinert & Freie Universität Berlin
// SPDX-FileCopyrightText: 2016-2026 Knut Reinert & MPI für molekulare Genetik
// SPDX-License-Identifier: BSD-3-Clause
 
#pragma once
 
#include <concepts>
#include <cstdint>
#include <iosfwd>
#include <string>
#include <string_view>
#include <vector>
 
namespace raptor
{
 
std::string json_quote(std::string_view const value);
 
std::string shortest_double(double const value);
 
class json_writer
{
public:
    json_writer() = delete;
    json_writer(json_writer const &) = delete;             // Would write to the same stream with a diverging state.
    json_writer & operator=(json_writer const &) = delete; // Would write to the same stream with a diverging state.
    json_writer(json_writer &&) = default;
    json_writer & operator=(json_writer &&) = delete; // reference member
    ~json_writer() = default;
 
    explicit json_writer(std::ostream & stream) : stream{stream}
    {}
 
    json_writer & key(std::string_view const name);
 
    json_writer & begin_object(bool const inline_elements = false);
    json_writer & end_object();
    json_writer & begin_array(bool const inline_elements = false);
    json_writer & end_array();
 
    json_writer & string(std::string_view const value);
    json_writer & boolean(bool const value);
    json_writer & null();
 
    template <std::unsigned_integral number_t>
    json_writer & number(number_t const value)
    {
        return write_unsigned(static_cast<uint64_t>(value));
    }
 
    template <std::floating_point number_t>
    json_writer & number(number_t const value)
    {
        return write_double(static_cast<double>(value));
    }
 
private:
    struct container
    {
        bool is_object{};
        bool inline_elements{};
        bool has_elements{};
    };
 
    std::ostream & stream;
    std::vector<container> open_containers{};
    bool has_key{false};
 
    void prepare_value();
    void write_separator(container & parent);
    void open(bool const is_object, bool const inline_elements);
    void close(bool const is_object);
    void indent(size_t const level);
    json_writer & write_unsigned(uint64_t const value);
    json_writer & write_double(double const value);
};
 
} // namespace raptor