idirstate: group private methods and attrs that are in the interface

This makes it a little more obvious at a glance what work is
left. Fortunately there's not a whole lot left. I suspect the ignore
logic is going to be the tricky bit.

Differential Revision: https://phab.mercurial-scm.org/D6839

mercurial/interfaces/dirstate.py

@@ -20,6 +20,19 b' class idirstate(interfaceutil.Interface)'
         the dirstate.
         '''
 
+    # TODO: all these private methods and attributes should be made
+    # public or removed from the interface.
+    _ignore = interfaceutil.Attribute('Matcher for ignored files.')
+
+    def _ignorefiles():
+        """Return a list of files containing patterns to ignore."""
+
+    def _ignorefileandline(f):
+        "Given a file `f`, return the ignore file and line that ignores it."
+
+    _checklink = interfaceutil.Attribute('Callable for checking symlinks.')
+    _checkexec = interfaceutil.Attribute('Callable for checking exec bits.')
+
     @contextlib.contextmanager
     def parentchange():
         '''Context manager for handling dirstate parents.
@@ -37,11 +50,6 b' class idirstate(interfaceutil.Interface)'
     def hasdir(d):
         pass
 
-    _ignore = interfaceutil.Attribute('Matcher for ignored files.')
-
-    _checklink = interfaceutil.Attribute('Callable for checking symlinks.')
-    _checkexec = interfaceutil.Attribute('Callable for checking exec bits.')
-
     def flagfunc(buildfallback):
         pass
 
@@ -196,16 +204,6 b' class idirstate(interfaceutil.Interface)'
         with a newer callback.
         """
 
-    def _ignorefiles():
-        """Return a list of files containing patterns to ignore.
-
-        TODO this should not be exposed."""
-
-    def _ignorefileandline(f):
-        """Given a file `f`, return the ignore file and line that ignores it.
-
-        TODO this should not be exposed."""
-
     def walk(match, subrepos, unknown, ignored, full=True):
         '''
         Walk recursively through the directory tree, finding all files