Add helper function find_path_attr

test/test_utils.py

@@ -4,6 +4,7 @@
 
 import sys
 import unittest
+import xml.etree.ElementTree
 
 # Allow direct execution
 import os
@@ -16,6 +17,7 @@ from youtube_dl.utils import unescapeHTML
 from youtube_dl.utils import orderedSet
 from youtube_dl.utils import DateRange
 from youtube_dl.utils import unified_strdate
+from youtube_dl.utils import find_xpath_attr
 
 if sys.version_info < (3, 0):
     _compat_str = lambda b: b.decode('unicode-escape')
@@ -112,5 +114,18 @@ class TestUtil(unittest.TestCase):
         self.assertEqual(unified_strdate('Dec 14, 2012'), '20121214')
         self.assertEqual(unified_strdate('2012/10/11 01:56:38 +0000'), '20121011')
 
+    def test_find_xpath_attr(self):
+        testxml = u'''<root>
+            <node/>
+            <node x="a"/>
+            <node x="a" y="c" />
+            <node x="b" y="d" />
+        </root>'''
+        doc = xml.etree.ElementTree.fromstring(testxml)
+
+        self.assertEqual(find_xpath_attr(doc, './/fourohfour', 'n', 'v'), None)
+        self.assertEqual(find_xpath_attr(doc, './/node', 'x', 'a'), doc[1])
+        self.assertEqual(find_xpath_attr(doc, './/node', 'y', 'c'), doc[2])
+
 if __name__ == '__main__':
     unittest.main()

youtube_dl/utils.py

@@ -198,6 +198,20 @@ else:
         with open(fn, 'w', encoding='utf-8') as f:
             json.dump(obj, f)
 
+if sys.version_info >= (2,7):
+    def find_xpath_attr(node, xpath, key, val):
+        """ Find the xpath xpath[@key=val] """
+        assert re.match(r'^[a-z]+$', key)
+        assert re.match(r'^[a-z]*$', val)
+        expr = xpath + u"[@%s='%s']" % (key, val)
+        return node.find(expr)
+else:
+    def find_xpath_attr(node, xpath, key, val):
+        for f in node.findall(xpath):
+            if f.attrib.get(key) == val:
+                return f
+        return None
+
 def htmlentity_transform(matchobj):
     """Transforms an HTML entity to a character.