MiniJava Language Reference Manual

COPYRIGHT NOTE: This manual is reproduced from Modern Compiler Implementation in Java, 2nd Edition, by Andrew W. Appel, page 484-486.

MiniJava is a subset of Java. The meaning of a MiniJava program is given by its meaning as a Java program. Overloading is not allowed in MiniJava. The MiniJava statement System.out.println(...); can only print integers. The MiniJava expression e.length only applies to expressions of type int[].

A.1 LEXICAL ISSUES

Identifiers:

An identifier is a sequence of letters, digits, and underscaores, starting with a letter. Uppercase letters are distinguished from lowercase. in this appendix the symbol id stands for an identifier.

Integer literals:

A sequence of decimal digits is an integer constant that denotes the corresponding integer value. in this appendix the symbol INTEGER_LITERAL stands for an integer constant.

Binary operators:

A binary operator is one of

&& < + - *

In this appendix the symbol op stands for a binary operator.

Comments:

A comment many appear between any two tokens. There are two forms of comments: One starts with /*, ends with */, and may be nested; another begins with // and goes to the end of the line.

A.2 GRAMMER

In the miniJava grammar, we use the notation N*, where N is a nonterminal, to mean 0, 1, or more repetitions of N.

Program    -> MainClass ClassDecl*

MainClass  -> class id { public static void main ( String [] id ) { Statement } }

ClassDecl  -> class id { VarDecl* MethodDecl* }
           -> class id extends id { VarDecl* MethodDecl* }

VarDecl    -> Type id ;

MethodDecl -> public Type id ( FormalList ) { VarDecl* Statement* return Exp ; }

FormalList -> Type id FormalRest*
           ->

FormalRest -> , Type id

Type       -> int []
           -> boolean
	   -> int
	   -> id

Statement  -> { Statement* }
           -> if ( Exp ) Statement else Statement
           -> while ( Exp ) Statement
	   -> System.out.println ( Exp ) ;
	   -> id = Exp ;
	   -> id [ Exp ] = Exp ;

Exp        -> Exp op Exp
           -> Exp [ Exp ]
	   -> Exp . length
	   -> Exp . id ( ExpList )
	   -> INTEGER_LITERAL
	   -> true
	   -> false
	   -> id
	   -> this
	   -> new int [ Exp ]
	   -> new id ( )
	   -> ! Exp
	   -> ( Exp )

ExpList    -> Exp ExpRest*
           ->

ExpRest    -> , Exp

A.3 SAMPLE PROGRAM

class Factorial {
    public static void main(String[] a) {
        System.out.println(new Fac().ComputeFac(10));
    }
}

class Fac {
    public int ComputeFac(int num) {
        int num_aux;
	if (num < 1)
	    num_aux = 1;
	else
	    num_aux = num * (this.ComputeFac(num - 1));
	return num_aux;
    }
}