add PackURI.relative_ref

Steve Canny · Steve Canny · commit 042c313359d1 · 2013-08-05T15:08:40.000-07:00
diff --git a/opc/packuri.py b/opc/packuri.py
@@ -72,6 +72,20 @@ def membername(self):
         """
         return self[1:]
 
+    def relative_ref(self, baseURI):
+        """
+        Return string containing relative reference to package item from
+        *baseURI*. E.g. PackURI('/ppt/slideLayouts/slideLayout1.xml') would
+        return '../slideLayouts/slideLayout1.xml' for baseURI '/ppt/slides'.
+        """
+        # workaround for posixpath bug in 2.6, doesn't generate correct
+        # relative path when *start* (second) parameter is root ('/')
+        if baseURI == '/':
+            relpath = self[1:]
+        else:
+            relpath = posixpath.relpath(self, baseURI)
+        return relpath
+
     @property
     def rels_uri(self):
         """
diff --git a/tests/test_packuri.py b/tests/test_packuri.py
@@ -66,6 +66,18 @@ def it_can_calculate_membername(self):
         for pack_uri, expected_membername in self.cases(expected_values):
             assert pack_uri.membername == expected_membername
 
+    def it_can_calculate_relative_ref_value(self):
+        cases = (
+            ('/', '/ppt/presentation.xml', 'ppt/presentation.xml'),
+            ('/ppt', '/ppt/slideMasters/slideMaster1.xml',
+             'slideMasters/slideMaster1.xml'),
+            ('/ppt/slides', '/ppt/slideLayouts/slideLayout1.xml',
+             '../slideLayouts/slideLayout1.xml'),
+        )
+        for baseURI, uri_str, expected_relative_ref in cases:
+            pack_uri = PackURI(uri_str)
+            assert pack_uri.relative_ref(baseURI) == expected_relative_ref
+
     def it_can_calculate_rels_uri(self):
         expected_values = (
             '/_rels/.rels',
