contrib/tcsh_completion

revset: use an iterator instead of a dequeue in ancestors()

The dequeue was actually just used to be able to pop value one at a time.
Building the dequeue means we are reading all the input value at once at the
beginning of the evaluation. This defeat the lazyness of revset.

We replace the deque with iterator usage for the sake of simplicity and
lazyness.

This provide massive speedup to get the first result if the input set is big

max(::all())
before) wall 0.001917 comb 0.000000 user 0.000000 sys 0.000000 (best of 1115)
after)  wall 0.000107 comb 0.000000 user 0.000000 sys 0.000000 (best of 22222)

#
# tcsh completion for Mercurial
#
# This file has been auto-generated by tcsh_completion_build.sh for
# Mercurial Distributed SCM (version 1.7.5+157-8a220ae0b2ba)
#
# Copyright (C) 2005 TK Soh.
#
# This is free software; you can redistribute it and/or modify it under
# the terms of the GNU General Public License as published by the Free
# Software Foundation; either version 2 of the License, or (at your
# option) any later version.
#

complete hg \
  'n/--cwd/d/' 'n/-R/d/' 'n/--repository/d/' \
  'C/-/( -R --repository \
    --cwd \
    -y --noninteractive \
    -q --quiet \
    -v --verbose \
    --config \
    --debug \
    --debugger \
    --encoding \
    --encodingmode \
    --traceback \
    --time \
    --profile \
    --version \
    -h --help)/' \
  'p/1/(add addremove annotate blame archive \
    backout bisect bookmarks branch branches \
    bundle cat clone commit ci \
    copy cp debugancestor debugbuilddag debugcheckstate \
    debugcommands debugcomplete debugdag debugdata debugdate \
    debugfsinfo debugignore debugindex debugindexdot debuginstall \
    debugpushkey debugrebuildstate debugrename debugrevspec debugsetparents \
    debugstate debugsub debugwalk diff export \
    forget grep heads help identify \
    id import patch incoming in \
    init locate log history manifest \
    merge outgoing out parents paths \
    pull push recover remove rm \
    rename move mv resolve revert \
    rollback root serve showconfig debugconfig \
    status st summary sum tag \
    tags tip unbundle update up \
    checkout co verify version)/'