// A small expression grammar in one combined file.
//   antlrlab examples/combined/Expr.g4 examples/combined/input.txt
grammar Expr;

prog : expr EOF ;

expr
    : expr op=(MUL | DIV) expr   # MulDiv
    | expr op=(ADD | SUB) expr   # AddSub
    | INT                        # Int
    | ID                         # Id
    | '(' expr ')'               # Parens
    ;

MUL : '*' ;
DIV : '/' ;
ADD : '+' ;
SUB : '-' ;
INT : [0-9]+ ;
ID  : [a-zA-Z_] [a-zA-Z_0-9]* ;
WS  : [ \t\r\n]+ -> skip ;