from django.template.loader import BaseLoader

class Loader(BaseLoader):

    is_usable = True

    def get_template_sources(self, template_name, template_dirs=None):

        """

        Returns the absolute paths to "template_name", when appended to each

        directory in "template_dirs". Any paths that don't lie inside one of the

        template dirs are excluded from the result set, for security reasons.

        """

        if not template_dirs:

            template_dirs = settings.TEMPLATE_DIRS

        for template_dir in template_dirs:

            try:

                yield safe_join(template_dir, template_name)

            except UnicodeDecodeError:

                # The template dir name was a bytestring that wasn't valid UTF-8.

                raise

            except ValueError:

                # The joined path was located outside of this particular

                # template_dir (it might be inside another one, so this isn't

                # fatal).

                pass

    def load_template_source(self, template_name, template_dirs=None):

        tried = []

        for filepath in self.get_template_sources(template_name, template_dirs):

            try:

                file = open(filepath)

                try:

                    return (file.read().decode(settings.FILE_CHARSET), filepath)

                finally:

                    file.close()

            except IOError:

                tried.append(filepath)

        if tried:

            error_msg = "Tried %s" % tried

        else:

            error_msg = "Your TEMPLATE_DIRS setting is empty. Change it to point to at least one template directory."

        raise TemplateDoesNotExist(error_msg)

    load_template_source.is_usable = True

_loader = Loader()

    # For backwards compatibility

    import warnings

    warnings.warn(

        "'django.template.loaders.filesystem.load_template_source' is deprecated; use 'django.template.loaders.filesystem.Loader' instead.",

        PendingDeprecationWarning

    )

    return _loader.load_template_source(template_name, template_dirs)