1 files changed, 118 insertions, 0 deletions
diff --git a/paste/debug/wdg_validate.py b/paste/debug/wdg_validate.py
new file mode 100644
index 0000000..225baf9
--- /dev/null
+++ b/paste/debug/wdg_validate.py
@@ -0,0 +1,118 @@
+# (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)