I'm still on the learning path with ANTLR. I've built a grammar and for the most part it does what I expect, but I need it to be able to run silently (no output to stdout or stderr).
Grammar
grammar MyPredicate;
options
{
output=AST;
}
parse : expression EOF
;
expression
: field WS? OPERATOR_BINARY WS? value
;
OPERATOR_BINARY
: '=' | '<' | '>' | '<=' | '>=' | '!=' | 'has'
;
value : VALUE_STRING
| VALUE_NUMERIC
| VALUE_BOOLEAN
;
VALUE_STRING
: '""'
| '"' (ESC_SEQ | ~('\\'|'"'))+ '"'
;
VALUE_NUMERIC
: ('0'..'9')+ ('.' ('0'..'9')+)?
;
VALUE_BOOLEAN
: 'true'
| 'false'
;
field : FIELD_NAME
;
FIELD_NAME
: ('a'..'z'|'A'..'Z'|'_') ('a'..'z'|'A'..'Z'|'0'..'9'|'_')*
;
ESC_SEQ
: '\\' ('b'|'t'|'n'|'f'|'r'|'\"'|'\''|'\\')
;
WS : (' ' | '\t' | '\r' | '\n') {skip();}
;
Java
import org.antlr.runtime.*;
import org.antlr.runtime.tree.*;
import org.antlr.stringtemplate.*;
public class Main {
public static void main(String[] args) throws Exception {
MyPredicateParser parser = new MyPredicateParser(new CommonTokenStream(new MyPredicateLexer(new ANTLRStringStream(args[0]))));
MyPredicateParser.parse_return r = parser.parse();
parser.parse();
if ( r.tree!=null ) {
System.out.println(((Tree)r.tree).toStringTree());
((CommonTree)r.tree).sanityCheckParentAndChildIndexes();
}
}
}
Input
a = 1
Output
line 0:-1 mismatched input '<EOF>' expecting FIELD_NAME
a = 1 null
I'm not sure why I get the EOF error. From what I understand my grammar is parsing correctly, and I get the error after the "parse" parser is evaluated, but that node is looking for the EOF. Using ANTLR 3.2