FunctionCall rule consuming all comments after match

The FunctionCall rule ends with this __expr = ''. This last match consumes all comments after this match until end of file or next rule match. This is no problem for the generated FunctionCall object. However, the attribute _tx_position_end is wrong and it is the position of the last consumed character. The model processor that includes the program source code to the workflow includes all these comments.

Here is an example reproducing this behavior:

from textx import metamodel_from_str
from textx import get_children_of_type

grammar_str = 'Program: objects *= Object[/^|;/]; Object: "object" name=ID expr=""; Comment: /#.*$/ | /(?ms)\"{3}(.*?)\"{3}/;'

meta = metamodel_from_str(grammar_str, auto_init_attributes=False)
model_str = '# comment\nobject a # blah \n# comment\nobject b; object c\n"""\nblahblah\n"""\n # more comment'
model = meta.model_from_str(model_str)

obj_list = get_children_of_type('Object', model)
for obj in obj_list:
    slc = slice(obj._tx_position, obj._tx_position_end)
    print(obj._tx_position, obj._tx_position_end, model_str[slc].rstrip())

Output:

10 37 object a # blah 
# comment
37 45 object b
47 88 object c
"""
blahblah
"""
 # more comment

By moving expr="" to the beginning of the Object rule avoids consuming the comments in this rule match, i.e. with

grammar_str = 'Program: objects *= Object[/^|;/]; Object: expr="" "object" name=ID; Comment: /#.*$/ | /(?ms)\"{3}(.*?)\"{3}/;'

we get this (the expected) output:

10 18 object a
37 45 object b
47 55 object c

Note that _tx_position_end is correct for object b because there is no comment after it in the source code.