# HG changeset patch
# User Vadim Gelfer <vadim.gelfer@gmail.com>
# Date 1150416450 25200
# Node ID c660691fb45d2cc1a411556e877e796c5a80b84c
# Parent  801dfe0aa53af984477b71fc29214babe1ffbb9a
http: query server for capabilities

diff --git a/mercurial/hgweb/hgweb_mod.py b/mercurial/hgweb/hgweb_mod.py
--- a/mercurial/hgweb/hgweb_mod.py
+++ b/mercurial/hgweb/hgweb_mod.py
@@ -833,3 +833,9 @@ class hgweb(object):
                                                   "static"))
         req.write(staticfile(static, fname)
                   or self.t("error", error="%r not found" % fname))
+
+    def do_capabilities(self, req):
+        resp = ''
+        req.httphdr("application/mercurial-0.1", length=len(resp))
+        req.write(resp)
+
diff --git a/mercurial/httprepo.py b/mercurial/httprepo.py
--- a/mercurial/httprepo.py
+++ b/mercurial/httprepo.py
@@ -71,7 +71,7 @@ def netlocunsplit(host, port, user=None,
 
 class httprepository(remoterepository):
     def __init__(self, ui, path):
-        self.capabilities = ()
+        self.caps = None
         scheme, netloc, urlpath, query, frag = urlparse.urlsplit(path)
         if query or frag:
             raise util.Abort(_('unsupported URL component: "%s"') %
@@ -145,6 +145,18 @@ class httprepository(remoterepository):
         opener.addheaders = [('User-agent', 'mercurial/proto-1.0')]
         urllib2.install_opener(opener)
 
+    # look up capabilities only when needed
+
+    def get_caps(self):
+        if self.caps is None:
+            try:
+                self.caps = self.do_read('capabilities').split()
+            except hg.RepoError:
+                self.caps = ()
+        return self.caps
+
+    capabilities = property(get_caps)
+
     def dev(self):
         return -1