comparison mercurial/scmutil.py @ 45720:508dfd1c18df

scmutil: move walkchangerevs() from cmdutil

It's no longer a command-level function, but a pure helper to walk revisions
in a windowed way. This change will help eliminate reverse dependency of
revset.py -> grep.py -> cmdutil.py in future patches.

45719:c10c87c8fe79

            spec = revsetlang.formatspec(b'%d', spec)
        allspecs.append(spec)
    return repo.anyrevs(allspecs, user=True, localalias=localalias)


def meaningfulparents(repo, ctx):
    """Return list of meaningful (or all if debug) parentrevs for rev.

    For merges (two non-nullrev revisions) both parents are meaningful.
    Otherwise the first parent revision is considered meaningful if it

45720:508dfd1c18df

            spec = revsetlang.formatspec(b'%d', spec)
        allspecs.append(spec)
    return repo.anyrevs(allspecs, user=True, localalias=localalias)


def increasingwindows(windowsize=8, sizelimit=512):
    while True:
        yield windowsize
        if windowsize < sizelimit:
            windowsize *= 2


def walkchangerevs(repo, revs, makefilematcher, prepare):
    '''Iterate over files and the revs in a "windowed" way.

    Callers most commonly need to iterate backwards over the history
    in which they are interested. Doing so has awful (quadratic-looking)
    performance, so we use iterators in a "windowed" way.

    We walk a window of revisions in the desired order.  Within the
    window, we first walk forwards to gather data, then in the desired
    order (usually backwards) to display it.

    This function returns an iterator yielding contexts. Before
    yielding each context, the iterator will first call the prepare
    function on each context in the window in forward order.'''

    if not revs:
        return []
    change = repo.__getitem__

    def iterate():
        it = iter(revs)
        stopiteration = False
        for windowsize in increasingwindows():
            nrevs = []
            for i in pycompat.xrange(windowsize):
                rev = next(it, None)
                if rev is None:
                    stopiteration = True
                    break
                nrevs.append(rev)
            for rev in sorted(nrevs):
                ctx = change(rev)
                prepare(ctx, makefilematcher(ctx))
            for rev in nrevs:
                yield change(rev)

            if stopiteration:
                break

    return iterate()


def meaningfulparents(repo, ctx):
    """Return list of meaningful (or all if debug) parentrevs for rev.

    For merges (two non-nullrev revisions) both parents are meaningful.
    Otherwise the first parent revision is considered meaningful if it