Added new middleware for debugging with print statemetns

1 files changed, 87 insertions, 0 deletions

diff --git a/paste/printdebug.py b/paste/printdebug.py
new file mode 100644
index 0000000..280356f
--- /dev/null
+++ b/paste/printdebug.py
@@ -0,0 +1,87 @@
+import sys
+from cStringIO import StringIO
+import re
+import cgi
+from paste.util import threadedprint
+from paste import wsgilib
+
+_threadedprint_installed = False
+
+__all__ = ['PrintDebugMiddleware']
+
+class TeeFile(object):
+
+    def __init__(self, *files):
+        self.files = files
+
+    def write(self, v):
+        for file in self.files:
+            file.write(v)
+
+class PrintDebugMiddleware(object):
+
+    """
+    This middleware captures all the printed statements, and inlines
+    them in HTML pages, so that you can see all the (debug-intended)
+    print statements in the page itself.  Install like::
+
+        important_middleware.append(
+            'paste.printdebug.PrintDebugMiddleware')
+
+    In your configuration file.
+    """
+
+    log_template = (
+        '<pre style="width: 40%%; border: 2px solid #000; '
+        'background-color: #ffd; color: #000; float: right;">'
+        '<b style="border-bottom: 1px solid #000">Log messages</b><br>'
+        '%s</pre>')
+
+    def __init__(self, subapp):
+        self.subapp = subapp
+
+    def __call__(self, environ, start_response):
+        global _threadedprint_installed
+        if not _threadedprint_installed:
+            # @@: Not strictly threadsafe
+            _threadedprint_installed = True
+            threadedprint.install(leave_stdout=True)
+        logged = StringIO()
+        if environ['paste.config'].get('printdebug_print_error'):
+            replacement_stdout = TeeFile(environ['wsgi.errors'], logged)
+        else:
+            replacement_stdout = logged
+        output = StringIO()
+        try:
+            threadedprint.register(replacement_stdout)
+            status, headers, body = wsgilib.capture_output(
+                environ, start_response, self.subapp)
+            if status is None:
+                # Some error occurred
+                status = '500 Server Error'
+                headers = [('Content-type', 'text/html')]
+                start_response(status, headers)
+                if not body:
+                    body = 'An error occurred'
+            content_type = wsgilib.header_value(headers, 'content-type')
+            if not content_type or not content_type.startswith('text/html'):
+                if replacement_stdout == logged:
+                    # Then the prints will be lost, unless...
+                    environ['wsgi.errors'].write(logged.getvalue())
+                return [body]
+            body = self.add_log(body, logged.getvalue())
+            return [body]
+        finally:
+            threadedprint.deregister()
+
+    _body_re = re.compile(r'<body[^>]*>', re.I)
+        
+    def add_log(self, html, log):
+        if not log:
+            return html
+        log = self.log_template % cgi.escape(log)
+        match = self._body_re.search(html)
+        if not match:
+            return log + html
+        else:
+            return html[:match.end()] + log + html[match.end():]