[antlr-interest] Java.g grammar issues & potential fix

[David Ewing]

Now that you remind me. The 1.4 Java grammar also includes generics, so 
shouldn't we call it 1.5? Of course, it is missing a number of other 
Java 1.5 language features, metadata being one of the more interesting 
ones. Is anybody working on adding this support?

Dave

On Apr 7, 2004, at 2:10 AM, Vincent Mallet wrote:

> Terence & All,
>
> A problem in Clover (code coverage for Java which uses antlr)
> prompted me to look at the java.g "1.4 update" grammar and I found
> a few problems with the lexer:
>  1. the grammar won't accept octal-looking floats or doubles
>     (09d for example)
>  2. the grammar will accept hexadecimal numbers with a fractional
>     part (0x12.34 for example)
>
> I have seen a fix for problem #1 in java.g version 1.21-october-2003
> but #2 is definitely broken.
>
> In an attempt to clarify that part of the grammar I came up with a
> version of the NUM_INT lexer rule which seems to be more correct and
> potentially easier to read (indentation might need some work).
>
> If you have an opinion on the new rule I would love to hear it.
>
> Here it goes:
> take java.g, truncate evertyhing after "NUM_INT", replace with:
>
>
>  ---cut-cut---
> // a numeric literal
> NUM_INT
>     :   // all floating point literals with a whole-number part
>         ( (DIGIT)+ ('.' | 'e' | 'E' | 'f' | 'F' | 'd' | 'D' ) )=>
> (DIGIT)+
>         (  (('.' (DIGIT)* (EXPONENT)? | EXPONENT )
>             (('f'|'F') { _ttype = NUM_FLOAT; } | ('d' | 'D')? {
> _ttype = NUM_DOUBLE; } )
>            )
>          | ( ('f'|'F') { _ttype = NUM_FLOAT; } )
>          | ( ('d'|'D') { _ttype = NUM_DOUBLE; } )
>         )
>
>     |   // all floating point literals with no whole-number part
> (possibly just '.')
>         '.' { _ttype = DOT; }
>         (DIGIT)+ (EXPONENT)?
>         ( ('f'|'F') { _ttype = NUM_FLOAT; } | ('d' | 'D')? { _ttype
> = NUM_DOUBLE; } )
>
>     |   // all decimal literals
>         (   '0' ('0'..'7')+              // octal
>           | ('1'..'9') (DIGIT)+          // decimal
>           | '0' ('x' | 'X') (HEX_DIGIT)+ // hexa
>           | '0'                          // decimal
>         )
>         (('l' | 'L') { _ttype = NUM_LONG; })?
>     ;
>
>
> // a couple protected methods to assist in matching floating point
> numbers
> protected
> DIGIT
> 	:	'0'..'9'
> 	;
>
> protected
> EXPONENT
> 	:	('e'|'E') ('+'|'-')? ('0'..'9')+
> 	;
>
>  ---cut-cut---
>
> Thanks,
>
>     Vince.
>
>
>
>
>
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>



 
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