namespaces: add nodemap property

This patch adds a node-to-name map property to the namespace. This is necessary
because we cannot simply invert the name-to-node map because we do not assume
the name-to-node map to be unique (for example, consider named branches: many
nodes have one branch name).

The node-to-name is helpful in log commands where we are already iterating over
a set of nodes and want to display some kind of naming information to the user.

mercurial/namespaces.py

@@ -1,90 +1,98 b''
 from i18n import _
 from mercurial import util
 
 def tolist(val):
     """
     a convenience method to return an empty list instead of None
     """
     if val is None:
         return []
     else:
         return [val]
 
 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.
+    More precisely, we define a list of names (the namespace), a mapping of
+    names to nodes, and a mapping from nodes to names. Each 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:
       'templatename': name to use for templating (usually the singular form
                       of the plural namespace name)
       'namemap': function that takes a name and returns a list of nodes
+      'nodemap': function that takes a node and returns a list of names
     """
 
     _names_version = 0
 
     def __init__(self):
         self._names = util.sortdict()
 
         addns = self.addnamespace
 
         # we need current mercurial named objects (bookmarks, tags, and
         # branches) to be initialized somewhere, so that place is here
         addns("bookmarks", "bookmark",
-              lambda repo, name: tolist(repo._bookmarks.get(name)))
+              lambda repo, name: tolist(repo._bookmarks.get(name)),
+              lambda repo, name: repo.nodebookmarks(name))
 
         addns("tags", "tag",
-              lambda repo, name: tolist(repo._tagscache.tags.get(name)))
+              lambda repo, name: tolist(repo._tagscache.tags.get(name)),
+              lambda repo, name: repo.nodetags(name))
 
         addns("branches", "branch",
-              lambda repo, name: tolist(repo.branchtip(name)))
+              lambda repo, name: tolist(repo.branchtip(name)),
+              lambda repo, node: [repo[node].branch()])
 
-    def addnamespace(self, namespace, templatename, namemap, order=None):
+    def addnamespace(self, namespace, templatename, namemap, nodemap,
+                     order=None):
         """
         register a namespace
 
         namespace: the name to be registered (in plural form)
         templatename: the name to use for templating
         namemap: function that inputs a node, output name(s)
+        nodemap: function that inputs a name, output node(s)
         order: optional argument to specify the order of namespaces
                (e.g. 'branches' should be listed before 'bookmarks')
         """
         val = {'templatename': templatename,
-               'namemap': namemap}
+               'namemap': namemap,
+               'nodemap': nodemap}
         if order is not None:
             self._names.insert(order, namespace, val)
         else:
             self._names[namespace] = val
 
     def singlenode(self, repo, name):
         """
         Return the 'best' node for the given name. Best means the first node
         in the first nonempty list returned by a name-to-nodes mapping function
         in the defined precedence order.
 
         Raises a KeyError if there is no such node.
         """
         for ns, v in self._names.iteritems():
             n = v['namemap'](repo, name)
             if n:
                 # return max revision number
                 if len(n) > 1:
                     cl = repo.changelog
                     maxrev = max(cl.rev(node) for node in n)
                     return cl.node(maxrev)
                 return n[0]
         raise KeyError(_('no such name: %s') % name)
 
     def templatename(self, namespace):
         """method that returns the template name of a namespace"""
         return self._names[namespace]['templatename']