class Escaper

class Escaper {
    // Characters that would cause a dumped string to require double quoting.
    public const REGEX_CHARACTER_TO_ESCAPE = "[\\x00-\\x1f]||…| |
|
";
    // Mapping arrays for escaping a double quoted string. The backslash is
    // first to ensure proper escaping because str_replace operates iteratively
    // on the input arrays. This ordering of the characters avoids the use of strtr,
    // which performs more slowly.
    private const ESCAPEES = [
        '\\',
        '\\\\',
        '\\"',
        '"',
        "\x00",
        "\x01",
        "\x02",
        "\x03",
        "\x04",
        "\x05",
        "\x06",
        "\x07",
        "\x08",
        "\t",
        "\n",
        "\v",
        "\f",
        "\r",
        "\x0e",
        "\x0f",
        "\x10",
        "\x11",
        "\x12",
        "\x13",
        "\x14",
        "\x15",
        "\x16",
        "\x17",
        "\x18",
        "\x19",
        "\x1a",
        "\x1b",
        "\x1c",
        "\x1d",
        "\x1e",
        "\x1f",
        "",
        "…",
        " ",
        "
",
        "
",
    ];
    private const ESCAPED = [
        '\\\\',
        '\\"',
        '\\\\',
        '\\"',
        '\\0',
        '\\x01',
        '\\x02',
        '\\x03',
        '\\x04',
        '\\x05',
        '\\x06',
        '\\a',
        '\\b',
        '\\t',
        '\\n',
        '\\v',
        '\\f',
        '\\r',
        '\\x0e',
        '\\x0f',
        '\\x10',
        '\\x11',
        '\\x12',
        '\\x13',
        '\\x14',
        '\\x15',
        '\\x16',
        '\\x17',
        '\\x18',
        '\\x19',
        '\\x1a',
        '\\e',
        '\\x1c',
        '\\x1d',
        '\\x1e',
        '\\x1f',
        '\\x7f',
        '\\N',
        '\\_',
        '\\L',
        '\\P',
    ];
    
    /**
     * Determines if a PHP value would require double quoting in YAML.
     *
     * @param string $value A PHP value
     */
    public static function requiresDoubleQuoting(string $value) : bool {
        return 0 < preg_match('/' . self::REGEX_CHARACTER_TO_ESCAPE . '/u', $value);
    }
    
    /**
     * Escapes and surrounds a PHP value with double quotes.
     *
     * @param string $value A PHP value
     */
    public static function escapeWithDoubleQuotes(string $value) : string {
        return \sprintf('"%s"', str_replace(self::ESCAPEES, self::ESCAPED, $value));
    }
    
    /**
     * Determines if a PHP value would require single quoting in YAML.
     *
     * @param string $value A PHP value
     */
    public static function requiresSingleQuoting(string $value) : bool {
        // Determines if a PHP value is entirely composed of a value that would
        // require single quoting in YAML.
        if (\in_array(strtolower($value), [
            'null',
            '~',
            'true',
            'false',
            'y',
            'n',
            'yes',
            'no',
            'on',
            'off',
        ])) {
            return true;
        }
        // Determines if the PHP value contains any single characters that would
        // cause it to require single quoting in YAML.
        return 0 < preg_match('/[\\s\'"\\:\\{\\}\\[\\],&\\*\\#\\?] | \\A[\\-?|<>=!%@`\\p{Zs}]/xu', $value);
    }
    
    /**
     * Escapes and surrounds a PHP value with single quotes.
     *
     * @param string $value A PHP value
     */
    public static function escapeWithSingleQuotes(string $value) : string {
        return \sprintf("'%s'", str_replace('\'', '\'\'', $value));
    }

}