added scrapy.utils.response module

--HG--
extra : convert_revision : svn%3Ab85faa78-f9eb-468e-a121-7cced6da292c%40301

scrapy/trunk/scrapy/utils/response.py

@@ -0,0 +1,15 @@
+"""
+This module provides some useful functions for working with
+scrapy.http.Response objects
+"""
+
+from scrapy.xpath import XPathSelector
+
+def new_response_from_xpaths(response, xpaths):
+    """Return a new response constructed by applying the given xpaths to the
+    original response body
+    """
+    xs = XPathSelector(response)
+    parts = [''.join([n for n in xs.x(x).extract()]) for x in xpaths]
+    new_body = ''.join(parts)
+    return response.replace(body=new_body)