ANTLR no viable alternative at input '/' - eclipse-plugin

Question

Okay, I'm really confused about this error. I know in the past having a '/' as a token in a rule hasn't produced any errors. However, this is simply baffling. Here is my grammar:
grammar LilWildC;
options {
language = Java;
}
#header
{
package com.matthewkimber.lilwildc;
}
#lexer::header
{
package com.matthewkimber.lilwildc;
}
program
: global_variables procedure+
;
global_variables
: variable_definition*
;
variable_definition
: 'number' IDENT ';'
| 'number' '[' A_NUMBER ']' IDENT ';'
;
procedure
: 'procedure' IDENT '{' block '}'
;
block
: local_variables statement+
;
local_variables
: variable_definition*
;
statement
: variable_reference '=' numeric_expression ';'
;
variable_reference
: IDENT
| IDENT '[' numeric_expression ']'
;
numeric_expression
: multiply_expression
( '+' multiply_expression
| '-' multiply_expression
)*
;
multiply_expression
: negative_factor
( '*' negative_factor
| '/' negative_factor
| '%' negative_factor
)*
;
negative_factor
: '-'? factor
;
factor
: A_NUMBER
| variable_reference
| '(' numeric_expression ')'
;
A_NUMBER: (('0'..'9')+'.'?) | (('0'..'9')*'.'('0'..'9')+) ;
IDENT: ('a'..'z' | 'A'..'Z')('a'..'z' | 'A'..'Z' | '0'..'9' | '_')* ;
WS: (' ' | '\t' | ('\r'?'\n'))+ { $channel = HIDDEN; } ;
When I run a test on the grammar with the following input:
procedure main
{
var = 10 / 1;
}
I get the following parse tree in the ANTLR eclipse plug-in:
What I don't get is that multiplication and modulo work fine, only divide throws this error. Is ANTLR skipping right over the '/' and not seeing it as a token or have I missed something? Any help is greatly appreciated.

Answer 1

There's nothing wrong with your grammar, the problem must be the Eclipse plugin. ANTLRWorks' debugger produces the tree:
And creating a little test myself (after fixing the typo grammary LilWildC; to grammar LilWildC;, and removing the packages) with a main class and ANTLR 3.3:
LilWildC.g
grammar LilWildC;
options {
language = Java;
}
program
: global_variables procedure+
;
global_variables
: variable_definition*
;
variable_definition
: 'number' IDENT ';'
| 'number' '[' A_NUMBER ']' IDENT ';'
;
p rocedure
: 'procedure' IDENT '{' block '}'
;
block
: local_variables statement+
;
local_variables
: variable_definition*
;
statement
: variable_reference '=' numeric_expression ';'
;
variable_reference
: IDENT
| IDENT '[' numeric_expression ']'
;
numeric_expression
: multiply_expression
( '+' multiply_expression
| '-' multiply_expression
)*
;
multiply_expression
: negative_factor
( '*' negative_factor
| '/' negative_factor
| '%' negative_factor
)*
;
negative_factor
: '-'? factor
;
factor
: A_NUMBER
| variable_reference
| '(' numeric_expression ')'
;
A_NUMBER: (('0'..'9')+'.'?) | (('0'..'9')*'.'('0'..'9')+) ;
IDENT: ('a'..'z' | 'A'..'Z')('a'..'z' | 'A'..'Z' | '0'..'9' | '_')* ;
WS: (' ' | '\t' | ('\r'?'\n'))+ { $channel = HIDDEN; } ;
Main.java
import org.antlr.runtime.*;
public class Main {
public static void main(String[] args) throws Exception {
String src =
"procedure main \n" +
"{ \n" +
" var = 10 / 1; \n" +
"} \n";
LilWildCLexer lexer = new LilWildCLexer(new ANTLRStringStream(src));
LilWildCParser parser = new LilWildCParser(new CommonTokenStream(lexer));
parser.program();
}
}
bart#hades:~/Programming/ANTLR/Demos/LilWildC$ java -cp antlr-3.3.jar org.antlr.Tool LilWildC.g
bart#hades:~/Programming/ANTLR/Demos/LilWildC$ javac -cp antlr-3.3.jar *.java
bart#hades:~/Programming/ANTLR/Demos/LilWildC$ java -cp .:antlr-3.3.jar Main
produces no errors or warnings.