hgweb: add websub template filter

hgweb: add websub template filter

The purpose of this new filter is to make it possible to partially replace the
functionality of the interhg extension. The idea is to be able to define regular
expression based substitutions on a new "websub" config section. hgweb will then
be able to apply these substitutions wherever the "websub" filter is used on a
template.

This first revision just adds the code necessary to load the websub expressions
and adds the websub filter, but it does not add any calls to the websub filter
itself on any of the templates. That will be done on the following revisions.

--- a/mercurial/hgweb/hgweb_mod.py	Tue Feb 05 14:36:19 2013 -0800
+++ b/mercurial/hgweb/hgweb_mod.py	Fri Feb 08 18:05:32 2013 +0100
@@ -8,11 +8,13 @@
 
 import os
 from mercurial import ui, hg, hook, error, encoding, templater, util, repoview
+from mercurial.templatefilters import websub
+from mercurial.i18n import _
 from common import get_stat, ErrorResponse, permhooks, caching
 from common import HTTP_OK, HTTP_NOT_MODIFIED, HTTP_BAD_REQUEST
 from common import HTTP_NOT_FOUND, HTTP_SERVER_ERROR
 from request import wsgirequest
-import webcommands, protocol, webutil
+import webcommands, protocol, webutil, re
 
 perms = {
     'changegroup': 'pull',
@@ -73,6 +75,7 @@
         # a repo owner may set web.templates in .hg/hgrc to get any file
         # readable by the user running the CGI script
         self.templatepath = self.config('web', 'templates')
+        self.websubtable = self.loadwebsub()
 
     # The CGI scripts are often run by a user different from the repo owner.
     # Trust the settings from the .hg/hgrc files by default.
@@ -258,6 +261,45 @@
                 return ['']
             return tmpl('error', error=inst.message)
 
+    def loadwebsub(self):
+        websubtable = []
+        websubdefs = self.repo.ui.configitems('websub')
+        for key, pattern in websubdefs:
+            # grab the delimiter from the character after the "s"
+            unesc = pattern[1]
+            delim = re.escape(unesc)
+
+            # identify portions of the pattern, taking care to avoid escaped
+            # delimiters. the replace format and flags are optional, but
+            # delimiters are required.
+            match = re.match(
+                r'^s%s(.+)(?:(?<=\\\\)|(?<!\\))%s(.*)%s([ilmsux])*$'
+                % (delim, delim, delim), pattern)
+            if not match:
+                self.repo.ui.warn(_("websub: invalid pattern for %s: %s\n")
+                                  % (key, pattern))
+                continue
+
+            # we need to unescape the delimiter for regexp and format
+            delim_re = re.compile(r'(?<!\\)\\%s' % delim)
+            regexp = delim_re.sub(unesc, match.group(1))
+            format = delim_re.sub(unesc, match.group(2))
+
+            # the pattern allows for 6 regexp flags, so set them if necessary
+            flagin = match.group(3)
+            flags = 0
+            if flagin:
+                for flag in flagin.upper():
+                    flags |= re.__dict__[flag]
+
+            try:
+                regexp = re.compile(regexp, flags)
+                websubtable.append((regexp, format))
+            except re.error:
+                self.repo.ui.warn(_("websub: invalid regexp for %s: %s\n")
+                                  % (key, regexp))
+        return websubtable
+
     def templater(self, req):
 
         # determine scheme, port and server name
@@ -311,9 +353,13 @@
                              or req.env.get('REPO_NAME')
                              or req.url.strip('/') or self.repo.root)
 
+        def websubfilter(text):
+            return websub(text, self.websubtable)
+
         # create the templater
 
         tmpl = templater.templater(mapfile,
+                                   filters={"websub": websubfilter},
                                    defaults={"url": req.url,
                                              "logourl": logourl,
                                              "logoimg": logoimg,

--- a/mercurial/templatefilters.py	Tue Feb 05 14:36:19 2013 -0800
+++ b/mercurial/templatefilters.py	Fri Feb 08 18:05:32 2013 +0100
@@ -391,6 +391,15 @@
     "xmlescape": xmlescape,
 }
 
+def websub(text, websubtable):
+    """:websub: Any text. Only applies to hgweb. Applies the regular
+    expression replacements defined in the websub section.
+    """
+    if websubtable:
+        for regexp, format in websubtable:
+            text = regexp.sub(format, text)
+    return text
+
 def fillfunc(context, mapping, args):
     if not (1 <= len(args) <= 2):
         raise error.ParseError(_("fill expects one or two arguments"))