hg

revset: introduce "_parsealiasdecl" to parse alias declarations strictly

This patch introduces "_parsealiasdecl" to parse alias declarations
strictly. For example, "_parsealiasdecl" can detect problems below,
which current implementation can't.

  - un-closed parenthesis causes being treated as "alias symbol"

    because all of declarations not in "func(....)" style are
    recognized as "alias symbol".

    for example, "foo($1, $2" is treated as the alias symbol.

  - alias symbol/function names aren't examined whether they are valid
    as symbol or not

    for example, "foo bar" can be treated as the alias symbol, but of
    course such invalid symbol can't be referred in revset.

  - just splitting argument list by "," causes overlooking syntax
    problems in the declaration

    for example, all of invalid declarations below are overlooked:

    - foo("bar")     => taking one argument named as '"bar"'
    - foo("unclosed) => taking one argument named as '"unclosed'
    - foo(bar::baz)  => taking one argument named as 'bar::baz'
    - foo(bar($1))   => taking one argument named as 'bar($1)'

To decrease complication of patch, current implementation for alias
declarations is replaced by "_parsealiasdecl" in the subsequent
patch. This patch just introduces it.

This patch defines "_parsealiasdecl" not as a method of "revsetalias"
class but as a one of "revset" module, because of ease of testing by
doctest.

This patch factors some helper functions for "tree" out, because:

  - direct accessing like "if tree[0] == 'func' and len(tree) > 1"
    decreases readability

  - subsequent patch (and also existing code paths, in the future) can
    use them for readability

This patch also factors "_tokenizealias" out, because it can be used
also for parsing alias definitions strictly.

#!/usr/bin/env python
#
# mercurial - scalable distributed SCM
#
# Copyright 2005-2007 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 os
import sys

if os.environ.get('HGUNICODEPEDANTRY', False):
    reload(sys)
    sys.setdefaultencoding("undefined")


libdir = '@LIBDIR@'

if libdir != '@' 'LIBDIR' '@':
    if not os.path.isabs(libdir):
        libdir = os.path.join(os.path.dirname(os.path.realpath(__file__)),
                              libdir)
        libdir = os.path.abspath(libdir)
    sys.path.insert(0, libdir)

# enable importing on demand to reduce startup time
try:
    from mercurial import demandimport; demandimport.enable()
except ImportError:
    import sys
    sys.stderr.write("abort: couldn't find mercurial libraries in [%s]\n" %
                     ' '.join(sys.path))
    sys.stderr.write("(check your install and PYTHONPATH)\n")
    sys.exit(-1)

import mercurial.util
import mercurial.dispatch

for fp in (sys.stdin, sys.stdout, sys.stderr):
    mercurial.util.setbinary(fp)

mercurial.dispatch.run()