source: release-kits/lirk3/resources/gs3-release-maker/apache-ant-1.6.5/src/etc/testcases/taskdefs/optional/antlr/antlr.g@ 14982

class CalcParser extends Parser;
options {
    buildAST = true;    // uses CommonAST by default
}

expr
    :   mexpr (PLUS^ mexpr)* SEMI!
    ;

mexpr
    :   atom (STAR^ atom)*
    ;

atom:   INT
    ;

class CalcLexer extends Lexer;

WS  :   (' '
    |   '\t'
    |   '\n'
    |   '\r')
        { _ttype = Token.SKIP; }
    ;

LPAREN: '('
    ;

RPAREN: ')'
    ;

STAR:   '*'
    ;

PLUS:   '+'
    ;

SEMI:   ';'
    ;

protected
DIGIT
    :   '0'..'9'
    ;

INT :   (DIGIT)+
    ;

class CalcTreeWalker extends TreeParser;

expr returns [float r]
{
    float a,b;
    r=0;
}
    :   #(PLUS a=expr b=expr)   {r = a+b;}
    |   #(STAR a=expr b=expr)   {r = a*b;}
    |   i:INT           {r = (float)Integer.parseInt(i.getText());}
    ;