[antlr-interest] AntlrWorks just hangs when trying to step through the tutorial..
Jeffrey Newman
jeffn at photorepo.com
Sun Dec 5 16:24:35 PST 2010
I'm just learning Antlr and AntlrWorks.
I have downloaded AntlrWorks (I assume antlr came with it).
It comes up. (On Linux 64, with the latest Java from Sun.
I put the java bins in my path. My CLASSPATH is empty.)
I started on the AntlrWorks tutorial.
Below is the grammer, and the events.
When I ran the interpreter, I was able to see a parse tree. Cool.
When I ran the debugger, it hung.
I tried to single step.
Below is as far as I got before it hung.
Can anyone explain why.
Now, back to Terence's book...
thanks
Jeffrey
>From Events.
0
Commence
1
Enter
rule /home/jeffn/Expr.g:prog
2
Location
(15,1)
3
Enter alt 1
4
Location
(15,9)
5
Enter
subrule 1
1
Grammer
rammar Expr;
@header {
package test;
import java.util.HashMap;
}
@lexer::header {package test;}
@members {
/** Map variable name to Integer object holding value */
HashMap memory = new HashMap();
}
prog: stat+ ;
stat: expr NEWLINE {System.out.println($expr.value);}
| ID '=' expr NEWLINE
{memory.put($ID.text, new Integer($expr.value));}
| NEWLINE
;
expr returns [int value]
: e=multExpr {$value = $e.value;}
( '+' e=multExpr {$value += $e.value;}
| '-' e=multExpr {$value -= $e.value;}
)*
;
multExpr returns [int value]
: e=atom {$value = $e.value;} ('*' e=atom {$value *= $e.value;})*
;
atom returns [int value]
: INT {$value = Integer.parseInt($INT.text);}
| ID
{
Integer v = (Integer)memory.get($ID.text);
if ( v!=null ) $value = v.intValue();
else System.err.println("undefined variable "+$ID.text);
}
| '(' e=expr ')' {$value = $e.value;}
;
ID : ('a'..'z'|'A'..'Z')+ ;
INT : '0'..'9'+ ;
NEWLINE:'\r'? '\n' ;
WS : (' '|'\t')+ {skip();} ;
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