Rely on more_itertools for unique_everseen for Python 2 compatibility.

CHANGES.rst

@@ -1,9 +1,12 @@
-v0.5.3
+v0.6.0
 ======
 
 #12: When adding implicit dirs, ensure that ancestral directories
 are added and that duplicates are excluded.
 
+The library now relies on
+`more_itertools <https://pypi.org/project/more_itertools>`_.
+
 v0.5.2
 ======
 

setup.cfg

@@ -22,6 +22,7 @@ packages = find:
 include_package_data = true
 python_requires = >=2.7
 install_requires =
+	more_itertools
 setup_requires = setuptools_scm >= 1.15.0
 
 [options.extras_require]

zipp.py

@@ -9,25 +9,9 @@
 import functools
 import itertools
 
-__metaclass__ = type
-
+import more_itertools
 
-def _unique_everseen(iterable, key=None):
-    "List unique elements, preserving order. Remember all elements ever seen."
-    # unique_everseen('AAAABBBCCDAABBB') --> A B C D
-    # unique_everseen('ABBCcAD', str.lower) --> A B C D
-    seen = set()
-    seen_add = seen.add
-    if key is None:
-        for element in itertools.filterfalse(seen.__contains__, iterable):
-            seen_add(element)
-            yield element
-    else:
-        for element in iterable:
-            k = key(element)
-            if k not in seen:
-                seen_add(k)
-                yield element
+__metaclass__ = type
 
 
 def _parents(path):
@@ -211,7 +195,7 @@ def joinpath(self, add):
 
     @staticmethod
     def _implied_dirs(names):
-        return _unique_everseen(
+        return more_itertools.unique_everseen(
             parent + "/"
             for name in names
             for parent in _parents(name)