Re: [Grammatica-users] Passing through

[Oliver Gramberg]

Hi Dave,

what exactly is it you want to pass
through - characters from the input stream, tokens, or a parse tree? From
what you say I take it that the internal parser is complete and self-contained,
so you are probably thinking of passing characters. First thing that comes
to my mind is, pass the exact same stream that you gave to the outer parser
to the inner parser at the correct location. Two caveats:
- When you call the inner parser in
some Exit... method, all input that corresponds to that rule will already
have been parsed, Exit... is post-processing.
- The parser may have read a substantial
number of characters from the input stream in order to produce enough look-ahead
tokens, depending on the complexity of your grammar.
My best guess, then, is that you should
define a very distinctive token that is to appear before the embedded parts,
to prevent the parser from reading ahead. Override that token's Exit...
method and try if the input stream still contains the beginning of the
following embedded part. If not, some refactoring of your grammar may help.

Regards
Oliver

---

Oliver Gramberg
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"Elliman, David" <address@hidden>
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14.09.2009 12:30

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Subject	[Grammatica-users] Passing through

Hi,

I have an application deployed using grammatica - it's great thanks.

However we want to make use of an _expression_ evaluator internally (probably Flee - which itself uses grammatica!) So ideally we would like to have some "Evaluate" production that simply passes through to the other internal parser (by specifically invoking it on the ExitEvaluateProduction(….) handler that I would supply. The problem of course it that the reg exp is too wide; I had definedthe token  PASS_THROUGH <<.+>> and now nothing works because it's too wide and capturing everything all the time. I know that the reg exps are context free WRT the productions which is leading to this but is there any other way to construct this pass through type functionality - other than upgrading our syntax to support everything supported in the internal parser?

Cheers, and thanks again

Dave

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