match: make explicitdir and traversedir None by default

With this, extensions can easily tell when traversedir and/or explicitdir don't
need to be called.

hgext/inotify/client.py

@@ -159,7 +159,8 b' class client(object):'
             vdirs = cs.read(nbytes)
             if vdirs:
                 for vdir in vdirs.split('\0'):
-                    match.explicitdir(vdir)
+                    if match.explicitdir:
+                        match.explicitdir(vdir)
 
         return results
 

mercurial/dirstate.py

@@ -623,7 +623,8 b' class dirstate(object):'
                     if nf in dmap:
                         #file deleted on disk but still in dirstate
                         results[nf] = None
-                    matchedir(nf)
+                    if matchedir:
+                        matchedir(nf)
                     if not dirignore(nf):
                         wadd(nf)
                 elif kind == regkind or kind == lnkkind:
@@ -639,7 +640,8 b' class dirstate(object):'
                     prefix = nf + "/"
                     for fn in dmap:
                         if fn.startswith(prefix):
-                            matchedir(nf)
+                            if matchedir:
+                                matchedir(nf)
                             skipstep3 = False
                             break
                     else:
@@ -668,7 +670,8 b' class dirstate(object):'
                 if nf not in results:
                     if kind == dirkind:
                         if not ignore(nf):
-                            matchtdir(nf)
+                            if matchtdir:
+                                matchtdir(nf)
                             wadd(nf)
                         if nf in dmap and (matchalways or matchfn(nf)):
                             results[nf] = None

mercurial/match.py

@@ -119,10 +119,8 b' class match(object):'
         found/accessed, with an error message
         '''
         pass
-    def explicitdir(self, f):
-        pass
-    def traversedir(self, f):
-        pass
+    explicitdir = None
+    traversedir = None
     def missing(self, f):
         pass
     def exact(self, f):