[antlr-interest] rules for complicated strings

[jbb at acm.org]

>How do I store a value read in from file, and reference the value later in
>the program?

I'd use a Hashtable, v is the key and d is its datum. And also study
the general Compiler literature regarding Symbol Tables and their use.

>Next, is there a good way I can specify a rule to represent complicated
>strings like this:
>
>P(age) --> {.g(1)[-(90)g(1).][g(MAX_P_LEN*func(2,age/DURATION)).][+(90)g(1).]}
>
>where parenthesis and brackets occur randomly and on both sides of the
>equation?

How 'bout this:
--------------------------------------------------
class hushlee83Parser extends Parser;
entry : expr EOF ;
expr :
	( OTHER
	| LPAREN expr RPAREN
	| LBRACE expr RBRACE
	| LBRACKET expr RBRACKET )+
    ;

class hushlee83Lexer extends Lexer;
options{charVocabulary='\3'..'\377';}
LPAREN : '(';
RPAREN : ')';
LBRACE : '{';
RBRACE : '}';
LBRACKET : '[';
RBRACKET : ']';
OTHER : (~('('|')'|'['|']'|'{'|'}'))+;

--------------------------------------------------
assuming that the parens, braces, and brackets must appear in pairs.

Hope this helps...

 

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