add missing lxml iterators module

scrapy/contrib_exp/iterators.py

@@ -0,0 +1,37 @@
+from scrapy.http import Response
+from scrapy.selector import XmlXPathSelector
+
+
+def xmliter_lxml(obj, nodename):
+    from lxml import etree
+    reader = _StreamReader(obj)
+    iterable = etree.iterparse(reader, tag=nodename, encoding=reader.encoding)
+    for _, node in iterable:
+        nodetext = etree.tostring(node)
+        node.clear()
+        yield XmlXPathSelector(text=nodetext).select('//' + nodename)[0]
+
+
+class _StreamReader(object):
+
+    def __init__(self, obj):
+        self._ptr = 0
+        if isinstance(obj, Response):
+            self._text, self.encoding = obj.body, obj.encoding
+        else:
+            self._text, self.encoding = obj, 'utf-8'
+        self._is_unicode = isinstance(self._text, unicode)
+
+    def read(self, n=65535):
+        self.read = self._read_unicode if self._is_unicode else self._read_string
+        return self.read(n).lstrip()
+
+    def _read_string(self, n=65535):
+        s, e = self._ptr, self._ptr + n
+        self._ptr = e
+        return self._text[s:e]
+
+    def _read_unicode(self, n=65535):
+        s, e = self._ptr, self._ptr + n
+        self._ptr = e
+        return self._text[s:e].encode('utf-8')