grammar FeatherweightJavaScript;


@header { package edu.sjsu.fwjs.parser; }

// Reserved words
IF        : 'if' ;
ELSE      : 'else' ;

// Literals
INT       : [1-9][0-9]* | '0' ;

// Symbols
MUL       : '*' ;
DIV       : '/' ;
SEPARATOR : ';' ;


// Whitespace and comments
NEWLINE   : '\r'? '\n' -> skip ;
LINE_COMMENT  : '//' ~[\n\r]* -> skip ;
WS            : [ \t]+ -> skip ; // ignore whitespace


// ***Parsing rules ***

/** The start rule */
prog: stat+ ;

stat: expr SEPARATOR                                    # bareExpr
    | IF '(' expr ')' block ELSE block                  # ifThenElse
    | IF '(' expr ')' block                             # ifThen
    ;

expr: expr op=( '*' | '/' | '%' ) expr                  # MulDivMod
    | INT                                               # int
    | '(' expr ')'                                      # parens
    ;

block: '{' stat* '}'                                    # fullBlock
     | stat                                             # simpBlock
     ;