[antlr-interest] newbie question about nondeterminism warning

[Stefan Schmidt]

Hi folks,

I have posted this message to the jGuru forum last week but noone answered
so I'll try it here :-)

I am VERY new to antlr. Part of my current work is to extend an existing
antlr file by some additional functionality.

Ok, here is what I would like to do:

integrate a function like this: (a*x) + (b*y) - z

where x,y,z are REAL numbers (could be negative) and a,b are variables.
Basically a linear function. The (a*x) or (b*y) or z can be repeated *
times.

Here is the code (extract) I am trying:

line 193: ts_function : ts_function_items | (PLUS^|MINUS^)
(PLUS^|MINUS^)?REAL SEMICOLON!;
line 194: ts_function_items : ts_function_item ((PLUS^|MINUS^)
ts_function_item)* ;
line 195: ts_function_item : LEFT_PARENTHESIS! ID (MUL^|DIV^)
(PLUS|MINUS)?REAL RIGHT_PARENTHESIS!;

When I compile this I get the following warning:

ANTLR Parser Generator   Version 2.7.5 (20050128)   1989-2005 jGuru.com
fcl/fcl.g:194: warning:nondeterminism upon
fcl/fcl.g:194:     k==1:MINUS,PLUS
fcl/fcl.g:194:     between alt 1 and exit branch of block

When I replace the 'offending' (PLUS^|MINUS^) with (MUL^|DIV^) it compiles,
but that's obviously not what I want.

I have taken this example from the Expression Evaluation Example at
http://supportweb.cs.bham.ac.uk/documentation/tutorials/docsystem/build/tutorials/antlr/antlr.html

Can anyone help me out here?

Thanks!

Regards,

Stefan Schmidt
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