Fixing issue from PR #128. Str. match in abstract rule.

[igordejanovic]

Fixes issue discovered in PR #128.

While I was there two bare except were fixed also.

[goto40]

Good work! It is great that textx is such a "defined" project. The unittests and the clarity of the code allows efficient analysis of observed effects and easy fixes!

I have a question about rules of the style "A: B| '(' C D ')'. Should such a "partly specialization" be disallowed and yield a grammar error? What should this meta model describe? A is a base of (C and D) together.... (???). See example (I pasted it at the end of the new regression test):

I could imagine that if we throw a grammar error if more than one rule is combined in such a case is maybe a good idea? Do you have an idea about the impact (someone uses something like this already?)?

def test_abstract_alternative_multiple_rules():
    grammar = r'''
    Model: a+=A;
    A: B | '(' C D ')';
    B: 'B' name=ID x=INT;
    C: 'C' name=ID;
    D: 'D' x=INT;
    '''

    mm = metamodel_from_str(grammar)

    modelstr = '''
    B b1 1
    B b2 2
    ( C c1 D 11 )
    ( C c2 D 12 )
    '''

    model = mm.model_from_str(modelstr)

    assert model.a[0].name == 'b1'
    assert model.a[0].x == 1
    assert textx_isinstance(model.a[0], mm['A'])
    assert textx_isinstance(model.a[0], mm['B'])
    assert not textx_isinstance(model.a[0], mm['C'])
    assert not textx_isinstance(model.a[0], mm['D'])

    assert model.a[2].name == 'c1'
    #assert model.a[2].x == 11                       # does not work
    assert textx_isinstance(model.a[2], mm['A'])
    assert not textx_isinstance(model.a[2], mm['B'])
    assert textx_isinstance(model.a[2], mm['C'])
    #assert textx_isinstance(model.a[2], mm['D'])  # fails

[goto40]

I would appreciate to clarify the use of rules like in the example (A:B| C D).

[igordejanovic]

Good point. I think that A: B | '(' C D ')'; should rise a grammar error during meta-model construction as C D combination doesn't make much sense to me. I'm not aware of any grammar that uses something like this.

[igordejanovic]

This PR has been cleaned up. I did a force push so please update your local branch. Furthermore, referencing multiple rules from a single choice of abstract rule is now explicitly disallowed by raising TextXSemanticError.

[goto40]

Great!

[goto40]

Ready to merge...