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"""This module is used to find files used by run-webkit-tests and
perftestrunner. It exposes one public function - find() - which takes
an optional list of paths, optional set of skipped directories and optional
filter callback.

If a list is passed in, the returned list of files is constrained to those
found under the paths passed in. i.e. calling find(["LayoutTests/fast"])
will only return files under that directory.

If a set of skipped directories is passed in, the function will filter out
the files lying in these directories i.e. find(["LayoutTests"], set(["fast"]))
will return everything except files in fast subfolder.

If a callback is passed in, it will be called for the each file and the file
will be included into the result if the callback returns True.
The callback has to take three arguments: filesystem, dirname and filename.
"""

import itertools


def find(filesystem, base_dir, paths=None, skipped_directories=None, file_filter=None, directory_sort_key=None):
    """Finds the set of tests under a given list of sub-paths.

    Args:
      paths: a list of path expressions relative to base_dir
          to search. Glob patterns are ok, as are path expressions with
          forward slashes on Windows. If paths is empty, we look at
          everything under the base_dir.
    """

    paths = paths or ['*']
    skipped_directories = skipped_directories or set(['.svn', '_svn'])
    return _normalized_find(filesystem, _normalize(
        filesystem, base_dir, paths), skipped_directories, file_filter, directory_sort_key)


def _normalize(filesystem, base_dir, paths):
    return [filesystem.normpath(filesystem.join(base_dir, path)) for path in paths]


def _normalized_find(filesystem, paths, skipped_directories, file_filter, directory_sort_key):
    """Finds the set of tests under the list of paths.

    Args:
      paths: a list of absolute path expressions to search.
          Glob patterns are ok.
    """

    paths_to_walk = itertools.chain(*(filesystem.glob(path) for path in paths))

    def sort_by_directory_key(files_list):
        if directory_sort_key:
            files_list.sort(key=directory_sort_key)
        return files_list

    all_files = itertools.chain(*(sort_by_directory_key(filesystem.files_under(path, skipped_directories, file_filter))
                                  for path in paths_to_walk))
    return all_files