json_like_out.hpp

// Copyright Takatoshi Kondo 2022
//
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
 
#if !defined(ASYNC_MQTT_UTIL_JSON_LIKE_OUT_HPP)
#define ASYNC_MQTT_UTIL_JSON_LIKE_OUT_HPP
 
#include <ostream>
#include <iomanip>
 
#include <async_mqtt/buffer.hpp>
 
namespace async_mqtt {
 
struct json_like_out_t {
    json_like_out_t(buffer const& buf): buf{buf} {}
 
    buffer const& buf;
};
 
inline std::ostream& operator<<(std::ostream& o, json_like_out_t const& v) {
    for (char c : v.buf) {
        switch (c) {
        case '\\':
            o << "\\\\";
            break;
        case '"':
            o << "\\\"";
            break;
        case '/':
            o << "\\/";
            break;
        case '\b':
            o << "\\b";
            break;
        case '\f':
            o << "\\f";
            break;
        case '\n':
            o << "\\n";
            break;
        case '\r':
            o << "\\r";
            break;
        case '\t':
            o << "\\t";
            break;
        default: {
            unsigned int code = static_cast<unsigned int>(c);
            if (code < 0x20 || code >= 0x7f) {
                std::ios::fmtflags flags(o.flags());
                o << "\\u" << std::hex << std::setw(4) << std::setfill('0') << (code & 0xff);
                o.flags(flags);
            }
            else {
                o << c;
            }
        } break;
        }
    }
    return o;
}
 
inline json_like_out_t json_like_out(buffer const& buf) {
    return json_like_out_t{buf};
}
 
} // namespace async_mqtt
 
#endif // ASYNC_MQTT_UTIL_JSON_LIKE_OUT_HPP