Method eval

src/bsh/BSHBinaryExpression.java:41–202

( CallStack callstack, Interpreter interpreter)

    BSHBinaryExpression(int id) { super(id); }

    public Object eval( CallStack callstack, Interpreter interpreter)  
		throws EvalError
    {
        Object lhs = ((SimpleNode)jjtGetChild(0)).eval(callstack, interpreter);

		/*
			Doing instanceof?  Next node is a type.
		*/
        if (kind == INSTANCEOF)
        {
			// null object ref is not instance of any type
			if ( lhs == Primitive.NULL )
				return Primitive.FALSE;

            Class rhs = ((BSHType)jjtGetChild(1)).getType( 
				callstack, interpreter );
		/*
			// primitive (number or void) cannot be tested for instanceof
            if (lhs instanceof Primitive)
				throw new EvalError("Cannot be instance of primitive type." );
		*/
			/*
				Primitive (number or void) is not normally an instanceof
				anything.  But for internal use we'll test true for the
				bsh.Primitive class.  
				i.e. (5 instanceof bsh.Primitive) will be true
			*/
			if ( lhs instanceof Primitive )
				if ( rhs == bsh.Primitive.class )
					return Primitive.TRUE;
				else
					return Primitive.FALSE;

			// General case - performe the instanceof based on assignability
            boolean ret = Types.isJavaBaseAssignable( rhs, lhs.getClass() );
            return new Primitive(ret);
        }


		// The following two boolean checks were tacked on.
		// This could probably be smoothed out.

		/*
			Look ahead and short circuit evaluation of the rhs if:
				we're a boolean AND and the lhs is false.
		*/
		if ( kind == BOOL_AND || kind == BOOL_ANDX ) {
			Object obj = lhs;
			if ( isPrimitiveValue(lhs) )
				obj = ((Primitive)lhs).getValue();
			if ( obj instanceof Boolean && 
				( ((Boolean)obj).booleanValue() == false ) )
				return Primitive.FALSE;
		}
		/*
			Look ahead and short circuit evaluation of the rhs if:
				we're a boolean AND and the lhs is false.
		*/