2245 def _parsealiasdefn(defn, args):

  2246     """Parse alias definition ``defn``

  2247 

  2248     This function also replaces alias argument references in the

  2249     specified definition by ``_aliasarg(ARGNAME)``.

  2250 

  2251     ``args`` is a list of alias argument names, or None if the alias

  2252     is declared as a symbol.

  2253 

  2254     This returns "tree" as parsing result.

  2255 

  2256     >>> args = ['$1', '$2', 'foo']

  2257     >>> print prettyformat(_parsealiasdefn('$1 or foo', args))

  2258     (or

  2259       (func

  2260         ('symbol', '_aliasarg')

  2261         ('string', '$1'))

  2262       (func

  2263         ('symbol', '_aliasarg')

  2264         ('string', 'foo')))

  2265     >>> try:

  2266     ...     _parsealiasdefn('$1 or $bar', args)

  2267     ... except error.ParseError, inst:

  2268     ...     print parseerrordetail(inst)

  2269     at 6: '$' not for alias arguments

  2270     >>> args = ['$1', '$10', 'foo']

  2271     >>> print prettyformat(_parsealiasdefn('$10 or foobar', args))

  2272     (or

  2273       (func

  2274         ('symbol', '_aliasarg')

  2275         ('string', '$10'))

  2276       ('symbol', 'foobar'))

  2277     >>> print prettyformat(_parsealiasdefn('"$1" or "foo"', args))

  2278     (or

  2279       ('string', '$1')

  2280       ('string', 'foo'))

  2281     """

  2282     def tokenizedefn(program, lookup=None):

  2283         if args:

  2284             argset = set(args)

  2285         else:

  2286             argset = set()

  2287 

  2288         for t, value, pos in _tokenizealias(program, lookup=lookup):

  2289             if t == 'symbol':

  2290                 if value in argset:

  2291                     # emulate tokenization of "_aliasarg('ARGNAME')":

  2292                     # "_aliasarg()" is an unknown symbol only used separate

  2293                     # alias argument placeholders from regular strings.

  2294                     yield ('symbol', '_aliasarg', pos)

  2295                     yield ('(', None, pos)

  2296                     yield ('string', value, pos)

  2297                     yield (')', None, pos)

  2298                     continue

  2299                 elif value.startswith('$'):

  2300                     raise error.ParseError(_("'$' not for alias arguments"),

  2301                                            pos)

  2302             yield (t, value, pos)

  2303 

  2304     p = parser.parser(tokenizedefn, elements)

  2305     tree, pos = p.parse(defn)

  2306     if pos != len(defn):

  2307         raise error.ParseError(_('invalid token'), pos)

  2308     return tree

  2309