json.cc

/*
 * Copyright (C) 2018 ScyllaDB
 */

/*
 * This file is part of Scylla.
 *
 * Scylla is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Scylla 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 Scylla.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "json.hh"

namespace seastar {
namespace json {

static inline bool is_control_char(char c) {
    return c >= 0 && c <= 0x1F;
}

static inline bool needs_escaping(const sstring& s) {
    return std::any_of(s.begin(), s.end(), [](char c) {return is_control_char(c) || c == '"' || c == '\\';});
}

sstring value_to_quoted_string(const sstring& value) {
    if (!needs_escaping(value)) {
        return sprint("\"%s\"", value);
    }
    std::ostringstream oss;
    oss << std::hex << std::uppercase << std::setfill('0');
    oss.put('"');
    for (char c : value) {
        switch (c) {
        case '"':
            oss.put('\\').put('"');
            break;
        case '\\':
            oss.put('\\').put('\\');
            break;
        case '\b':
            oss.put('\\').put('b');
            break;
        case '\f':
            oss.put('\\').put('f');
            break;
        case '\n':
            oss.put('\\').put('n');
            break;
        case '\r':
            oss.put('\\').put('r');
            break;
        case '\t':
            oss.put('\\').put('t');
            break;
        default:
            if (is_control_char(c)) {
                oss.put('\\').put('u') << std::setw(4) << static_cast<int>(c);
            } else {
                oss.put(c);
            }
            break;
        }
    }
    oss.put('"');
    return oss.str();
}

}

}