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Re: [bpfk] One cannot refer to inner nodes in Lojban PEG

I guess I don't follow. If string_1 doesn't want to have all of the possible string_3 realizations inside, then why does it ask for string_3? In this example, just use

string_1 = string_2 / string_6 string_8

instead. Can you make a more concrete example? What specific "actions" differ depending on whether a term contains FA or BAI?

mu'o mi'e durkavore

On Tuesday, April 7, 2015 at 4:28 AM, Gleki Arxokuna wrote:

Consider the following:
string_1 = string_2 / string_6 string_3
string_3 = string_7 / string_8
string_4 = !string_1 string_5 

Now we need !string_1 to work only if string_8 matches, not when string_7 matches.
Why we might need that? E.g. for terms that can have either FA or BAI inside. Depending on whether we have FA or BAI inside a term our actions may differ.

How can we implement that?
We can just create duplicates of two strings like this:

string_1 = string_2 / string_6 string_3
string_1_2 = string_2 / string_6 string_3_2
string_3 = string_7 / string_8
string_3_2 = string_8
string_4 = !string_1_2 string_5 

Now string_1_2 is the same as string_1 but it is matched only if string_8 matches (unlike string_1, otherwise they are the same).

Now the question is how do we avoid such duplication?

The answer from peg.js developers:
<quote>
Sorry, but there is currently no clean way to avoid the duplication.

In the future I'm thinking about adding support for rule templates/parametrizable rules, which would help here:

string_1<T> = string_2 / string_6 T
string_3 = string_7 / string_8
string_3_2 = string_8
string_4 = !string_1<string_3_2> string_5 

And I think it'd be nice 
</quote>

So for now our only chance is to copy paster parts of Lojban PEG if we want such things. I.e. one would need to split terms into "terms_for_BAI", "terms_for_FA" etc. with all their inner variables copied.

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