Class yii\helpers\Json

                public static function decode($json, $asArray = true)
{
    if (is_array($json)) {
        throw new InvalidArgumentException('Invalid JSON data.');
    } elseif ($json === null || $json === '') {
        return null;
    }
    $decode = json_decode((string) $json, $asArray);
    static::handleJsonError(json_last_error());
    return $decode;
}

            

                public static function encode($value, $options = 320)
{
    $expressions = [];
    $value = static::processData($value, $expressions, uniqid('', true));
    set_error_handler(function () {
        static::handleJsonError(JSON_ERROR_SYNTAX);
    }, E_WARNING);
    if (static::$prettyPrint === true) {
        $options |= JSON_PRETTY_PRINT;
    } elseif (static::$prettyPrint === false) {
        $options &= ~JSON_PRETTY_PRINT;
    }
    $json = json_encode($value, $options);
    restore_error_handler();
    static::handleJsonError(json_last_error());
    return $expressions === [] ? $json : strtr($json, $expressions);
}

            

                public static function errorSummary($models, $options = [])
{
    $showAllErrors = ArrayHelper::remove($options, 'showAllErrors', false);
    $lines = self::collectErrors($models, $showAllErrors);
    return static::encode($lines);
}

            

                protected static function handleJsonError($lastError)
{
    if ($lastError === JSON_ERROR_NONE) {
        return;
    }
    if (PHP_VERSION_ID >= 50500) {
        throw new InvalidArgumentException(json_last_error_msg(), $lastError);
    }
    foreach (static::$jsonErrorMessages as $const => $message) {
        if (defined($const) && constant($const) === $lastError) {
            throw new InvalidArgumentException($message, $lastError);
        }
    }
    throw new InvalidArgumentException('Unknown JSON encoding/decoding error.');
}

            

                public static function htmlEncode($value)
{
    return static::encode($value, JSON_UNESCAPED_UNICODE | JSON_HEX_QUOT | JSON_HEX_TAG | JSON_HEX_AMP | JSON_HEX_APOS);
}

            

                protected static function processData($data, &$expressions, $expPrefix)
{
    $revertToObject = false;
    if (is_object($data)) {
        if ($data instanceof JsExpression) {
            $token = "!{[$expPrefix=" . count($expressions) . ']}!';
            $expressions['"' . $token . '"'] = $data->expression;
            return $token;
        }
        if ($data instanceof \JsonSerializable) {
            return static::processData($data->jsonSerialize(), $expressions, $expPrefix);
        }
        if ($data instanceof \DateTimeInterface) {
            return static::processData((array)$data, $expressions, $expPrefix);
        }
        if ($data instanceof Arrayable) {
            $data = $data->toArray();
        } elseif ($data instanceof \Generator) {
            $_data = [];
            foreach ($data as $name => $value) {
                $_data[$name] = static::processData($value, $expressions, $expPrefix);
            }
            $data = $_data;
        } elseif ($data instanceof \SimpleXMLElement) {
            $data = (array) $data;
            // Avoid empty elements to be returned as array.
            // Not breaking BC because empty array was always cast to stdClass before.
            $revertToObject = true;
        } else {
            /*
             * $data type is changed to array here and its elements will be processed further
             * We must cast $data back to object later to keep intended dictionary type in JSON.
             * Revert is only done when keepObjectType flag is provided to avoid breaking BC
             */
            $revertToObject = static::$keepObjectType;
            $result = [];
            foreach ($data as $name => $value) {
                $result[$name] = $value;
            }
            $data = $result;
            // Avoid empty objects to be returned as array (would break BC without keepObjectType flag)
            if ($data === []) {
                $revertToObject = true;
            }
        }
    }
    if (is_array($data)) {
        foreach ($data as $key => $value) {
            if (is_array($value) || is_object($value)) {
                $data[$key] = static::processData($value, $expressions, $expPrefix);
            }
        }
    }
    return $revertToObject ? (object) $data : $data;
}