RE: Grammar to automation translation at runtime (NOT at compile time)?

> Therefore, my question is if there is any thought/effort to make the
> grammar to automation (a computational service) make
> available at run
> time? I am interested in CFG based generators (current impls are
> JavaCC, ANTLR).
>
> If this would be possible, I just have to supply a grammar
> file at run
> time to validate an ASCII stream -- I do not have to make a
> commitment
> at compile time. Only commitment I make that I will supply a valid
> grammar file to which the ASCII stream is validated (no nore grammar
> to Java/C# codegen/compile/write code on top of generated code).
>
> I took a look at Recursive Adaptive Grammar (which blurs the
> distinction between grammar vs automation) and it may hold certian
> potential towards dynamic grammar based validation.


Meta-S allows grammars to be instantiated at run-time from strings
(which could be stored in text files). The CLpmGrammar class has a
member function:


  bool InstantiateFromString(const CShuString& ssGrammar, bool
bDoSemanticChecks);


So, for instance, if your grammar is saved as an .abn file, which in
flat ASCII, looks something like this:


grammar TheGrammar
{
S ::= A B C;
A ::= /* whatever */;
// etc;
};


You do something like this:


CLpmGrammar gmr;


CShuString ssGrammar = LoadFromFile("the_grammar.abn");
CShuString ssTestInput = LoadFromFile("test_input.txt");


if(gmr.InstantiateFromString(ssGrammar, false))
{
if(gmr.Accept(ssTestInput))
{
// you can now traverse the parse tree
}
else
{
// grammar did not accept input
}
}


You can effectively do the above with the ABN2CPP utility (included
with Meta-S) thusly:


abn2cpp the_grammar.abn -i test_input.txt


You can develop your grammars either in a simple text editor, in
Meta-S Lite, or in Meta-S, a graphical grammar development environment
which allows you to debug the grammar against test input.


For more information, either visit http://www.meta-s.com or email me
directly.


Cheers.
--
Quinn Tyler Jackson

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