source: trunk/yao/share/antlr-2.7.7/examples/python/heteroAST/hetero.g @ 1

// This file is part of PyANTLR. See LICENSE.txt for license
// details..........Copyright (C) Wolfgang Haefelinger, 2004.
//
// $Id$

header {
    import hetero
}

options {
    language=Python;
}

/** This example demonstrates the heterogeneous tree construction
 *  mechanism.  Compare this example to examples/calc/calc.g
 *  to see that I use tree node methods not a tree walker to compute
 *  the result.
 */
class hetero_p extends Parser;
options {
        buildAST = true;        // uses CommonAST by default
}

// define a bunch of specific AST nodes to build.
// can override at actual reference of tokens in grammar
// below.
tokens {
        PLUS<AST=hetero.PLUSNode>;
        STAR<AST=hetero.MULTNode>;
}

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

mexpr
        :       atom (STAR^ atom)*
        ;

atom:   INT<AST=hetero.INTNode> // could have done in tokens{} section
        ;

class hetero_l extends Lexer;

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

LPAREN: '('
        ;

RPAREN: ')'
        ;

STAR:   '*'
        ;

PLUS:   '+'
        ;

SEMI:   ';'
        ;

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

INT     :       (DIGIT)+
        ;