Find files.

        Returns:
            list: the list of matching files.

def matching_files(self):
        """
        Find files.

        Returns:
            list: the list of matching files.
        """
        matching = []
        matcher = self.file_path_regex
        pieces = self.file_path_regex.pattern.split(sep)
        partial_matchers = list(map(re.compile, (
            sep.join(pieces[:i + 1]) for i in range(len(pieces)))))

        for root, dirs, files in walk(self.top_dir, topdown=True):
            for i in reversed(range(len(dirs))):
                dirname = relpath(join(root, dirs[i]), self.top_dir)
                dirlevel = dirname.count(sep)
                if not partial_matchers[dirlevel].match(dirname):
                    del dirs[i]

            for filename in files:
                if matcher.match(filename):
                    matching.append(abspath(join(root, filename)))

        return matching