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# (c) 2005 Ian Bicking and contributors; written for Paste (http://pythonpaste.org)
# Licensed under the MIT license: http://www.opensource.org/licenses/mit-license.php
"""
Middleware that tests the validity of all generated HTML using the
`WDG HTML Validator <http://www.htmlhelp.com/tools/validator/>`_
"""
from cStringIO import StringIO
import subprocess
from paste.response import header_value
import re
import cgi
__all__ = ['WDGValidateMiddleware']
class WDGValidateMiddleware(object):
"""
Middleware that checks HTML and appends messages about the validity of
the HTML. Uses: http://www.htmlhelp.com/tools/validator/ -- interacts
with the command line client. Use the configuration ``wdg_path`` to
override the path (default: looks for ``validate`` in $PATH).
To install, in your web context's __init__.py::
def urlparser_wrap(environ, start_response, app):
return wdg_validate.WDGValidateMiddleware(app)(
environ, start_response)
Or in your configuration::
middleware.append('paste.wdg_validate.WDGValidateMiddleware')
"""
_end_body_regex = re.compile(r'</body>', re.I)
def __init__(self, app, global_conf=None, wdg_path='validate'):
self.app = app
self.wdg_path = wdg_path
def __call__(self, environ, start_response):
output = StringIO()
response = []
def writer_start_response(status, headers, exc_info=None):
response.extend((status, headers))
start_response(status, headers, exc_info)
return output.write
app_iter = self.app(environ, writer_start_response)
try:
for s in app_iter:
output.write(s)
finally:
if hasattr(app_iter, 'close'):
app_iter.close()
page = output.getvalue()
status, headers = response
v = header_value(headers, 'content-type') or ''
if (not v.startswith('text/html')
and not v.startswith('text/xhtml')
and not v.startswith('application/xhtml')):
# Can't validate
# @@: Should validate CSS too... but using what?
return [page]
ops = []
if v.startswith('text/xhtml+xml'):
ops.append('--xml')
# @@: Should capture encoding too
html_errors = self.call_wdg_validate(
self.wdg_path, ops, page)
if html_errors:
page = self.add_error(page, html_errors)[0]
headers.remove(
('Content-Length',
str(header_value(headers, 'content-length'))))
headers.append(('Content-Length', str(len(page))))
return [page]
def call_wdg_validate(self, wdg_path, ops, page):
if subprocess is None:
raise ValueError(
"This middleware requires the subprocess module from "
"Python 2.4")
proc = subprocess.Popen([wdg_path] + ops,
shell=False,
close_fds=True,
stdout=subprocess.PIPE,
stdin=subprocess.PIPE,
stderr=subprocess.STDOUT)
stdout = proc.communicate(page)[0]
proc.wait()
return stdout
def add_error(self, html_page, html_errors):
add_text = ('<pre style="background-color: #ffd; color: #600; '
'border: 1px solid #000;">%s</pre>'
% cgi.escape(html_errors))
match = self._end_body_regex.search(html_page)
if match:
return [html_page[:match.start()]
+ add_text
+ html_page[match.start():]]
else:
return [html_page + add_text]
def make_wdg_validate_middleware(
app, global_conf, wdg_path='validate'):
"""
Wraps the application in the WDG validator from
http://www.htmlhelp.com/tools/validator/
Validation errors are appended to the text of each page.
You can configure this by giving the path to the validate
executable (by default picked up from $PATH)
"""
return WDGValidateMiddleware(
app, global_conf, wdg_path=wdg_path)
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