src/JmesPath/Utils.php
public static function type($arg)
    {
        $type = gettype($arg);
        if (isset(self::$typeMap[$type])) {
            return self::$typeMap[$type];
        } elseif ($type === 'array') {
            if (empty($arg)) {
                return 'array';
            }
            reset($arg);
            return key($arg) === 0 ? 'array' : 'object';
        } elseif ($arg instanceof \stdClass) {
            return 'object';
        } elseif ($arg instanceof JmesPathableObjectInterface) {
            return 'object';
        } elseif ($arg instanceof \Closure) {
            return 'expression';
        } elseif ($arg instanceof \ArrayAccess
            && $arg instanceof \Countable
        ) {
            return count($arg) == 0 || $arg->offsetExists(0)
                ? 'array'
                : 'object';
        } elseif (method_exists($arg, '__toString')) {
            return 'string';
        }

        throw new \InvalidArgumentException(
            'Unable to determine JMESPath type from ' . get_class($arg)
        );
    }
public static function type($arg)
    {
        $type = gettype($arg);
        if (isset(self::$typeMap[$type])) {
            return self::$typeMap[$type];
        } elseif ($type === 'array') {
            if (empty($arg)) {
                return 'array';
            }
            reset($arg);
            return key($arg) === 0 ? 'array' : 'object';
        } elseif ($arg instanceof \stdClass) {
            return 'object';
        } elseif ($arg instanceof JmesPathableObjectInterface) {
            return 'object';
        } elseif ($arg instanceof \Closure) {
            return 'expression';
        } elseif ($arg instanceof \ArrayAccess
            && $arg instanceof \Countable
        ) {
            return count($arg) == 0 || $arg->offsetExists(0)
                ? 'array'
                : 'object';
        } elseif (method_exists($arg, '__toString')) {
            return 'string';
        }

        throw new \InvalidArgumentException(
            'Unable to determine JMESPath type from ' . get_class($arg)
        );
    }
Gets the JMESPath type equivalent of a PHP variable.

@param mixed $arg PHP variable
@return string Returns the JSON data type
@throws \InvalidArgumentException when an unknown type is given.