comparison mercurial/templatefuncs.py @ 44592:7cd5c0968139

templater: add subsetparents(rev, revset) function

Naming suggestions are welcome. And this could be flagged as an (ADVANCED)
function since the primary use case is to draw a graph.

This provides all data needed for drawing revisions graph filtered by revset,
and allows us to implement a GUI graph viewer in some languages better than
Python. A frontend grapher will be quite similar to our graphmod since
subsetparents() just returns parent-child relations in the filtered sub graph.

Frontend example:

  https://hg.sr.ht/~yuja/hgv/browse/default/core/hgchangesetgrapher.cpp

However, the resulting graph will be simpler than the one "hg log -G" would
generate because redundant edges are eliminated. This should be the same graph
rendering strategy as TortoiseHg.

This function could be implemented as a revset predicate, but that would mean
the scanning state couldn't be cached and thus slow.

Test cases are split to new file since test-template-functions.t is quite
big and we'll need a new branchy repository anyway.

44591:1f81f680912f

    bin,
    wdirid,
)
from . import (
    color,
    diffutil,
    encoding,
    error,
    minirst,
    obsutil,

    if text.startswith(patn):
        return text
    return b''


@templatefunc(b'word(number, text[, separator])')
def word(context, mapping, args):
    """Return the nth word from a string."""
    if not (2 <= len(args) <= 3):
        # i18n: "word" is a keyword

44592:7cd5c0968139

    bin,
    wdirid,
)
from . import (
    color,
    dagop,
    diffutil,
    encoding,
    error,
    minirst,
    obsutil,

    if text.startswith(patn):
        return text
    return b''


@templatefunc(
    b'subsetparents(rev, revset)',
    argspec=b'rev revset',
    requires={b'repo', b'cache'},
)
def subsetparents(context, mapping, args):
    """Look up parents of the rev in the sub graph given by the revset."""
    if b'rev' not in args or b'revset' not in args:
        # i18n: "subsetparents" is a keyword
        raise error.ParseError(_(b"subsetparents expects two arguments"))

    repo = context.resource(mapping, b'repo')

    rev = templateutil.evalinteger(context, mapping, args[b'rev'])

    # TODO: maybe subsetparents(rev) should be allowed. the default revset
    # will be the revisions specified by -rREV argument.
    q = templateutil.evalwrapped(context, mapping, args[b'revset'])
    if not isinstance(q, templateutil.revslist):
        # i18n: "subsetparents" is a keyword
        raise error.ParseError(_(b"subsetparents expects a queried revset"))
    subset = q.tovalue(context, mapping)
    key = q.cachekey

    if key:
        # cache only if revset query isn't dynamic
        cache = context.resource(mapping, b'cache')
        walkercache = cache.setdefault(b'subsetparentswalker', {})
        if key in walkercache:
            walker = walkercache[key]
        else:
            walker = dagop.subsetparentswalker(repo, subset)
            walkercache[key] = walker
    else:
        # for one-shot use, specify startrev to limit the search space
        walker = dagop.subsetparentswalker(repo, subset, startrev=rev)
    return templateutil.revslist(repo, walker.parentsset(rev))


@templatefunc(b'word(number, text[, separator])')
def word(context, mapping, args):
    """Return the nth word from a string."""
    if not (2 <= len(args) <= 3):
        # i18n: "word" is a keyword