src/PropertyAccessor.php
public function getValue($object, $path)
    {
        $paths = (array) preg_split('#(\[((?>[^\[\]]+)|(?R))*\])#i', $path, -1, PREG_SPLIT_NO_EMPTY | PREG_SPLIT_DELIM_CAPTURE);

        for ($i = 0; $i < count($paths); ++$i) {
            $path = trim((string) $paths[$i], '.');
            if ('[' == substr($path, 0, 1)) {
                ++$i;
            }
            if (preg_match('#[^a-z0-9\.\]\[]+#i', $path)) {
                $expression = trim($path, '[]');
                $object = $this->filter($object, $expression);
            } else {
                $object = $this->accessor->getValue($object, $path);
            }

            if (null === $object) {
                break;
            }
        }

        return $object;
    }
public function getValue($object, $path)
    {
        $paths = (array) preg_split('#(\[((?>[^\[\]]+)|(?R))*\])#i', $path, -1, PREG_SPLIT_NO_EMPTY | PREG_SPLIT_DELIM_CAPTURE);

        for ($i = 0; $i < count($paths); ++$i) {
            $path = trim((string) $paths[$i], '.');
            if ('[' == substr($path, 0, 1)) {
                ++$i;
            }
            if (preg_match('#[^a-z0-9\.\]\[]+#i', $path)) {
                $expression = trim($path, '[]');
                $object = $this->filter($object, $expression);
            } else {
                $object = $this->accessor->getValue($object, $path);
            }

            if (null === $object) {
                break;
            }
        }

        return $object;
    }
Returns the value at the given path.

@param mixed  $object
@param string $path

@return mixed