from mercurial import revset

from mercurial import util

try:

    mkmatcher = revset._stringmatcher

except AttributeError:

    mkmatcher = util.stringmatcher

def topicset(repo, subset, x):

    """`topic([topic])`

    Specified topic or all changes with any topic specified.

    If `topic` starts with `re:` the remainder of the name is treated

    as a regular expression.

    TODO: make `topic(revset)` work the same as `branch(revset)`.

    """

    args = revset.getargs(x, 0, 1, 'topic takes one or no arguments')

    if args:

        # match a specific topic

        topic = revset.getstring(args[0], 'topic() argument must be a string')

        if topic == '.':

            topic = repo['.'].extra().get('topic', '')

        _kind, _pattern, matcher = mkmatcher(topic)

    else:

        matcher = lambda t: bool(t)

    drafts = subset.filter(lambda r: repo[r].mutable())

    return drafts.filter(

        lambda r: matcher(repo[r].extra().get(constants.extrakey, '')))

def ngtipset(repo, subset, x):

    """`ngtip([branch])`

    The untopiced tip.

    Name is horrible so that people change it.

    """

    args = revset.getargs(x, 1, 1, 'topic takes one')

    # match a specific topic

    branch = revset.getstring(args[0], 'ngtip() argument must be a string')

    if branch == '.':

        branch = repo['.'].branch()

    return subset & destination.ngtip(repo, branch)

def modsetup():

    revset.symbols.update({'topic': topicset})

    revset.symbols.update({'ngtip': ngtipset})