context: add 'dirs()' to changectx/workingctx for directory patterns stable

context: add 'dirs()' to changectx/workingctx for directory patterns

this patch adds 'dirs()' to changectx/workingctx, which returns map of
all directories deduced from manifest, to examine whether specified
pattern is related to the context as directory or not quickly.

'workingctx.dirs()' uses 'dirstate.dirs()' rather than building
another copy of it.

--- a/mercurial/context.py	Mon Feb 20 17:59:48 2012 +0100
+++ b/mercurial/context.py	Thu Feb 23 00:07:54 2012 +0900
@@ -236,6 +236,22 @@
         return patch.diff(self._repo, ctx2.node(), self.node(),
                           match=match, opts=diffopts)
 
+    @propertycache
+    def _dirs(self):
+        dirs = set()
+        for f in self._manifest:
+            pos = f.rfind('/')
+            while pos != -1:
+                f = f[:pos]
+                if f in dirs:
+                    break # dirs already contains this and above
+                dirs.add(f)
+                pos = f.rfind('/')
+        return dirs
+
+    def dirs(self):
+        return self._dirs
+
 class filectx(object):
     """A filecontext object makes access to data related to a particular
        filerevision convenient."""
@@ -953,6 +969,9 @@
             finally:
                 wlock.release()
 
+    def dirs(self):
+        return self._repo.dirstate.dirs()
+
 class workingfilectx(filectx):
     """A workingfilectx object makes access to data related to a particular
        file in the working directory convenient."""

--- a/mercurial/dirstate.py	Mon Feb 20 17:59:48 2012 +0100
+++ b/mercurial/dirstate.py	Thu Feb 23 00:07:54 2012 +0900
@@ -110,6 +110,9 @@
                 _incdirs(dirs, f)
         return dirs
 
+    def dirs(self):
+        return self._dirs
+
     @propertycache
     def _ignore(self):
         files = [self._join('.hgignore')]