Antlr whitespace token error - parsing

Question

I have the following grammar and I want to match the String "{name1, name2}". I just want lists of names/intergers with at least one element. However I get the error:
line 1:6 no viable alternative at character ' '
line 1:11 no viable alternative at character '}'
line 1:7 mismatched input 'name' expecting SIMPLE_VAR_TYPE
I would expect whitespaces and such are ignored... Also interesting is the error does not occur with input "{name1,name2}" (no space after ',').
Heres my gramar
grammar NusmvInput;
options {
language = Java;
}
#header {
package secltlmc.grammar;
}
#lexer::header {
package secltlmc.grammar;
}
specification :
SIMPLE_VAR_TYPE EOF
;
INTEGER
: ('0'..'9')+
;
SIMPLE_VAR_TYPE
: ('{' (NAME | INTEGER) (',' (NAME | INTEGER))* '}' )
;
NAME
: ('A'..'Z' | 'a'..'z') ('a'..'z' | 'A'..'Z' | '0'..'9' | '_' | '$' | '#' | '-')*
;
WS
: (' ' | '\t' | '\n' | '\r')+ {$channel = HIDDEN;}
;
And this is my testing code
package secltlmc;
public class Main {
public static void main(String[] args) throws
IOException, RecognitionException {
CharStream stream = new ANTLRStringStream("{name1, name2}");
NusmvInputLexer lexer = new NusmvInputLexer(stream);
CommonTokenStream tokenStream = new CommonTokenStream(lexer);
NusmvInputParser parser = new NusmvInputParser(tokenStream);
parser.specification();
}
}
Thanks for your help.

Answer 1

The problem is that you are trying to parse SIMPLE_VAR_TYPE with the lexer, i.e. you are trying to make it a single token. In reality, it looks like you want a multi-token production, since you'd like whitespace to be re-directed to hidden channel through WS.
You should change SIMPLE_VAR_TYPE from a lexer rule to a parser rule by changing its initial letter (or better yet, the entire name) to lower case.
specification :
simple_var_type EOF
;
simple_var_type
: ('{' (NAME | INTEGER) (',' (NAME | INTEGER))* '}' )
;

Answer 2

The defintion of SIMPLE_VAR_TYPE specifies the following expression:
Open {
followed by one of NAME or INTEGER
follwoed by zero or more of:
comma (,) followed by one of NAME or INTEGER
followed by closing }
Nowhere does it allow white-space in the input (neither NAME nor INTEGER allows it either), so you get an error when you supply one
Try:
SIMPLE_VAR_TYPE
: ('{' (NAME | INTEGER) (WS* ',' WS* (NAME | INTEGER))* '}' )
;