[antlr-interest] Another parsing question

Gavin Lambert antlr at mirality.co.nz
Mon Aug 4 14:45:09 PDT 2008


At 08:45 5/08/2008, Carter Cheng wrote:
 >Thanks everyone for the help thus far. This is likely another
 >beginners question concerning the behavior of the lexer/parser
 >interactions in ANTLRv3. The question I have is are the tokens
 >requested by the parser context dependent? i.e. is a different
 >(N)DFA constructed depending on which tokens the parser expects 
to
 >see in the stream or is there only 1 N(DFA) with a series of 
stop
 >states.

Lexing is all done up front with no input from the parser at all.

 >(a[1]); // lookup the index 1 in the variable array a
 >
 >([ 1 : 2 ]); // construct a mapping value with key : value in 
this
 >case 1 : 2
 >
 >The question I have is how can ANTLRv3 know whether ]) is a 
single
 >token or two tokens?

Depends on how you've defined the lexer rules :)  But normally 
you'd want to define it as two tokens.



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