+
+@six.python_2_unicode_compatible
+class WLURI(object):
+ """Represents a WL URI. Extracts slug from it."""
+ slug = None
+
+ example = 'http://wolnelektury.pl/katalog/lektura/template/'
+ _re_wl_uri = re.compile(r'http://(www\.)?wolnelektury.pl/katalog/lektur[ay]/'
+ '(?P<slug>[-a-z0-9]+)/?$')
+
+ def __init__(self, uri):
+ uri = six.text_type(uri)
+ self.uri = uri
+ self.slug = uri.rstrip('/').rsplit('/', 1)[-1]
+
+ @classmethod
+ def strict(cls, uri):
+ match = cls._re_wl_uri.match(uri)
+ if not match:
+ raise ValidationError(u'Invalid URI (%s). Should match: %s' % (
+ uri, cls._re_wl_uri.pattern))
+ return cls(uri)
+
+ @classmethod
+ def from_slug(cls, slug):
+ """Contructs an URI from slug.
+
+ >>> print(WLURI.from_slug('a-slug').uri)
+ http://wolnelektury.pl/katalog/lektura/a-slug/
+
+ """
+ uri = 'http://wolnelektury.pl/katalog/lektura/%s/' % slug
+ return cls(uri)
+
+ def __str__(self):
+ return self.uri
+
+ def __eq__(self, other):
+ return self.slug == other.slug
+
+
+class DocProvider(object):
+ """Base class for a repository of XML files.
+
+ Used for generating joined files, like EPUBs.
+ """
+
+ def by_slug(self, slug):
+ """Should return a file-like object with a WL document XML."""
+ raise NotImplementedError
+
+ def by_uri(self, uri, wluri=WLURI):
+ """Should return a file-like object with a WL document XML."""
+ wluri = wluri(uri)
+ return self.by_slug(wluri.slug)
+
+
+class DirDocProvider(DocProvider):
+ """ Serve docs from a directory of files in form <slug>.xml """
+
+ def __init__(self, dir_):
+ self.dir = dir_
+ self.files = {}
+
+ def by_slug(self, slug):
+ fname = slug + '.xml'
+ return open(os.path.join(self.dir, fname), 'rb')
+
+
+from . import dcparser