namespaces: add a method to register new namespaces

mercurial/namespaces.py

@@ -1,25 +1,40 b''
 from mercurial import util
 
 class namespaces(object):
     """
     provides an interface to register a generic many-to-many mapping between
     some (namespaced) names and nodes. The goal here is to control the
     pollution of jamming things into tags or bookmarks (in extension-land) and
     to simplify internal bits of mercurial: log output, tab completion, etc.
 
     More precisely, we define a list of names (the namespace) and  a mapping of
     names to nodes. This name mapping returns a list of nodes.
 
     Furthermore, each name mapping will be passed a name to lookup which might
     not be in its domain. In this case, each method should return an empty list
     and not raise an error.
 
     We'll have a dictionary '_names' where each key is a namespace and
     its value is a dictionary of functions:
       'namemap': function that takes a name and returns a list of nodes
     """
 
     _names_version = 0
 
     def __init__(self):
         self._names = util.sortdict()
+
+    def addnamespace(self, namespace, namemap, order=None):
+        """
+        register a namespace
+
+        namespace: the name to be registered (in plural form)
+        namemap: function that inputs a node, output name(s)
+        order: optional argument to specify the order of namespaces
+               (e.g. 'branches' should be listed before 'bookmarks')
+        """
+        val = {'namemap': namemap}
+        if order is not None:
+            self._names.insert(order, namespace, val)
+        else:
+            self._names[namespace] = val