view mercurial/namespaces.py @ 23553:7cebb6a8c75f

namespaces: introduce a generic way to map between names and nodes

This patch begins the work to provide a way to register a namespace to handle
'names'. Benefits of this would be,

- improved templating: This would provide {name} which could output any branch,
  bookmark, tag, or any extension registered namespace all without having the
  extension doing any extra work

- improved tab completion: Since this provides a single source of all 'names',
  tab completion would not need to know of each namespace

- changeset lookup: Similar to before, a unified place to get all 'names' will
  allow finding changesets without any extension code having to reimplement
  this

Also, d226fe36e362 has shown us that for internal code which expects a certain
type of method or behavior, we should provide an easy way for extensions to
check this behavior.

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()