comparison mercurial/templater.py @ 34330:89aec1834a86

templatekw: add new-style template expansion to {manifest}

The goal is to allow us to easily access to nested data. The dot operator
will be introduced later so we can write '{p1.files}' instead of
'{revset("p1()") % "{files}"}' for example.

In the example above, 'p1' needs to carry a mapping dict along with its
string representation. If it were a list or a dict, it could be wrapped
semi-transparently with the _hybrid class, but for non-list/dict types,
it would be difficult to proxy all necessary functions to underlying value
type because several core operations may conflict with the ones of the
underlying value:

 - hash(value) should be different from hash(wrapped(value)), which means
   dict[wrapped(value)] would be invalid
 - 'value == wrapped(value)' would be false, breaks 'ifcontains'
 - len(wrapped(value)) may be either len(value) or len(iter(wrapped(value)))

So the wrapper has no proxy functions and its scope designed to be minimal.
It's unwrapped at eval*() functions so we don't have to care for a wrapped
object unless it's really needed:

  # most template functions just call evalfuncarg()
  unwrapped_value = evalfuncarg(context, mapping, args[n])
  # if wrapped value is needed, use evalrawexp()
  maybe_wrapped_value = evalrawexp(context, mapping, args[n])

Another idea was to wrap every template variable with a tagging class, but
which seemed uneasy without a static type checker.

This patch updates {manifest} to a mappable as an example.

34329:6367318327f0

    return func(context, mapping, data)

def evalfuncarg(context, mapping, arg):
    """Evaluate given argument as value type"""
    thing = evalrawexp(context, mapping, arg)
    # evalrawexp() may return string, generator of strings or arbitrary object
    # such as date tuple, but filter does not want generator.
    if isinstance(thing, types.GeneratorType):
        thing = stringify(thing)
    return thing

        if thing is None:
            # not a template keyword, takes as a boolean literal
            thing = util.parsebool(data)
    else:
        thing = func(context, mapping, data)
    if isinstance(thing, bool):
        return thing
    # other objects are evaluated as strings, which means 0 is True, but
    # empty dict/list should be False as they are expected to be ''
    return bool(stringify(thing))

        raise error.ParseError(_("join expects one or two arguments"))

    # TODO: perhaps this should be evalfuncarg(), but it can't because hgweb
    # abuses generator as a keyword that returns a list of dicts.
    joinset = evalrawexp(context, mapping, args[0])
    joinfmt = getattr(joinset, 'joinfmt', pycompat.identity)
    joiner = " "
    if len(args) > 1:
        joiner = evalstring(context, mapping, args[1])

34330:89aec1834a86

    return func(context, mapping, data)

def evalfuncarg(context, mapping, arg):
    """Evaluate given argument as value type"""
    thing = evalrawexp(context, mapping, arg)
    thing = templatekw.unwrapvalue(thing)
    # evalrawexp() may return string, generator of strings or arbitrary object
    # such as date tuple, but filter does not want generator.
    if isinstance(thing, types.GeneratorType):
        thing = stringify(thing)
    return thing

        if thing is None:
            # not a template keyword, takes as a boolean literal
            thing = util.parsebool(data)
    else:
        thing = func(context, mapping, data)
    thing = templatekw.unwrapvalue(thing)
    if isinstance(thing, bool):
        return thing
    # other objects are evaluated as strings, which means 0 is True, but
    # empty dict/list should be False as they are expected to be ''
    return bool(stringify(thing))

        raise error.ParseError(_("join expects one or two arguments"))

    # TODO: perhaps this should be evalfuncarg(), but it can't because hgweb
    # abuses generator as a keyword that returns a list of dicts.
    joinset = evalrawexp(context, mapping, args[0])
    joinset = templatekw.unwrapvalue(joinset)
    joinfmt = getattr(joinset, 'joinfmt', pycompat.identity)
    joiner = " "
    if len(args) > 1:
        joiner = evalstring(context, mapping, args[1])