Hi all,
I'm facing a problem on my grammar that I don't know how to solve
(Antlr3.3)...
Let me show you my grammar. Simplified, of course. It's just to show you my
trouble.
grammar Cobol;
options {
language = Java;
}
program : 'procedure' 'division' '.' section*;
section : ID 'section' '.' paragraph*;
paragraph : ID '.' block* '.';
block : command*;
command: (cmdA | cmdB | cmdC ) '.'?;
cmdA: 'A';
cmdB: 'B';
cmdC: 'C';
fragment Digit : '0'..'9';
fragment Letter : ('a'..'z' | 'A'..'Z');
ID : Letter ( Letter | Digit | '-' )*;
Using this grammar, I'm having the following errors and warnings:
warning(200): /Cobol/src/Cobol.g:14:12: Decision can match input such as
"{'.', 'A'..'C'}" using multiple alternatives: 1, 2
As a result, alternative(s) 2 were disabled for that input
|---> ID '.' block* '.';
error(201): /Cobol/src/Cobol.g:14:12: The following alternatives can never
be matched: 2
|---> ID '.' block* '.';
warning(200): /Cobol/src/Cobol.g:17:5: Decision can match input such as
"'B'" using multiple alternatives: 1, 2
As a result, alternative(s) 2 were disabled for that input
|---> command*;
warning(200): /Cobol/src/Cobol.g:17:5: Decision can match input such as
"'A'" using multiple alternatives: 1, 2
As a result, alternative(s) 2 were disabled for that input
|---> command*;
warning(200): /Cobol/src/Cobol.g:17:5: Decision can match input such as
"'C'" using multiple alternatives: 1, 2
As a result, alternative(s) 2 were disabled for that input
|---> command*;
4 warnings
1 error
BUILD FAIL
My real problem is:
1) any 'command' can be followed by a '.'
2) any sequence of 'command's not followed by '.' forms a 'block'
3) wherever I can use a 'command', I can use a 'block'
4) the '.' signifies the end of a 'block'
5) I can use any number of 'block's to form a 'paragraph'
6) I can use any number of 'paragraph's to form a 'section'
7) I can have any number of 'section's on a 'program'
Any hints or help about what am I doing wrong? I'm completely stuck on it,
'cause I'm a little newbie using Antlr...
TIA,
Nilo - Brazil
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