view mercurial/ancestor.py @ 12536:208fc9ad6a48

alias: only allow global options before a shell alias, pass later ones through

This patch refactors the dispatch code to change how arguments to shell aliases
are handled.

A separate "pass" to determine whether a command is a shell alias has been
added. The rough steps dispatch now performs when a command is given are these:

* Parse all arguments up to the command name.

* If any arguments such as --repository or --cwd are given (which could change
  the config file used, and therefore the definition of aliases), they are
  taken into account.

* We determine whether the command is a shell alias.

    * If so, execute the alias. The --repo and --cwd arguments are still in effect.
      Any arguments *after* the command name are passed unchanged through to the
      shell command (and interpolated as normal.

    * If the command is *not* a shell alias, the dispatching is effectively "reset"
      and reparsed as normal in its entirety.

The net effect of this patch is to make shell alias commands behave as you
would expect.

Any arguments you give to a shell alias *after* the alias name are passed
through unchanged. This lets you do something like the following:

    [alias]
    filereleased = !$HG log -r 'descendants(adds("$1")) and tagged()' -l1 $2 $3 $4 $5

    $ hg filereleased hgext/bookmarks.py --style compact

Previously the `--style compact` part would fail because Mercurial would
interpret those arguments as arguments to the alias command itself (which
doesn't take any arguments).

Also: running something like `hg -R ~/src/hg-crew filereleased
hgext/bookmarks.py` when `filereleased` is only defined in that repo's config
will now work.

These global arguments can *only* be given to a shell alias *before* the alias
name.  For example, this will *not* work in the above situation:

    $ hg filereleased -R ~/src/hg-crew hgext/bookmarks.py

The reason for this is that you may want to pass arguments like --repository to
the alias (or, more likely, their short versions like -R):

    [alias]
    own = !chown $@ `$HG root`

    $ hg own steve
    $ hg own -R steve

# ancestor.py - generic DAG ancestor algorithm for mercurial
#
# Copyright 2006 Matt Mackall <[e-mail]>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

import heapq

def ancestor(a, b, pfunc):
    """
    return a minimal-distance ancestor of nodes a and b, or None if there is no
    such ancestor. Note that there can be several ancestors with the same
    (minimal) distance, and the one returned is arbitrary.

    pfunc must return a list of parent vertices for a given vertex
    """

    if a == b:
        return a

    a, b = sorted([a, b])

    # find depth from root of all ancestors
    parentcache = {}
    visit = [a, b]
    depth = {}
    while visit:
        vertex = visit[-1]
        pl = pfunc(vertex)
        parentcache[vertex] = pl
        if not pl:
            depth[vertex] = 0
            visit.pop()
        else:
            for p in pl:
                if p == a or p == b: # did we find a or b as a parent?
                    return p # we're done
                if p not in depth:
                    visit.append(p)
            if visit[-1] == vertex:
                depth[vertex] = min([depth[p] for p in pl]) - 1
                visit.pop()

    # traverse ancestors in order of decreasing distance from root
    def ancestors(vertex):
        h = [(depth[vertex], vertex)]
        seen = set()
        while h:
            d, n = heapq.heappop(h)
            if n not in seen:
                seen.add(n)
                yield (d, n)
                for p in parentcache[n]:
                    heapq.heappush(h, (depth[p], p))

    def generations(vertex):
        sg, s = None, set()
        for g, v in ancestors(vertex):
            if g != sg:
                if sg:
                    yield sg, s
                sg, s = g, set((v,))
            else:
                s.add(v)
        yield sg, s

    x = generations(a)
    y = generations(b)
    gx = x.next()
    gy = y.next()

    # increment each ancestor list until it is closer to root than
    # the other, or they match
    try:
        while 1:
            if gx[0] == gy[0]:
                for v in gx[1]:
                    if v in gy[1]:
                        return v
                gy = y.next()
                gx = x.next()
            elif gx[0] > gy[0]:
                gy = y.next()
            else:
                gx = x.next()
    except StopIteration:
        return None