/*

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * particular file as subject to the "Classpath" exception as provided

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 */

package javax.management;

/**

 * This class is used by the query-building mechanism to represent binary

 * operations.

 * @serial include

 *

 * @since 1.5

 */

class BinaryOpValueExp extends QueryEval implements ValueExp {

    /* Serial version */

    private static final long serialVersionUID = 1216286847881456786L;

    /**

     * @serial The operator

     */

    private int op;

    /**

     * @serial The first value

     */

    private ValueExp exp1;

    /**

     * @serial The second value

     */

    private ValueExp exp2;

    /**

     * Basic Constructor.

     */

    public BinaryOpValueExp() {

    }

    /**

     * Creates a new BinaryOpValueExp using operator o applied on v1 and

     * v2 values.

     */

    public BinaryOpValueExp(int o, ValueExp v1, ValueExp v2) {

        op   = o;

        exp1 = v1;

        exp2 = v2;

    }

    /**

     * Returns the operator of the value expression.

     */

    public int getOperator()  {

        return op;

    }

    /**

     * Returns the left value of the value expression.

     */

    public ValueExp getLeftValue()  {

        return exp1;

    }

    /**

     * Returns the right value of the value expression.

     */

    public ValueExp getRightValue()  {

        return exp2;

    }

    /**

     * Applies the BinaryOpValueExp on a MBean.

     *

     * @param name The name of the MBean on which the BinaryOpValueExp will be applied.

     *

     * @return  The ValueExp.

     *

     * @exception BadStringOperationException

     * @exception BadBinaryOpValueExpException

     * @exception BadAttributeValueExpException

     * @exception InvalidApplicationException

     */

    public ValueExp apply(ObjectName name) throws BadStringOperationException, BadBinaryOpValueExpException,

        BadAttributeValueExpException, InvalidApplicationException  {

        ValueExp val1 = exp1.apply(name);

        ValueExp val2 = exp2.apply(name);

        String sval1;

        String sval2;

        double dval1;

        double dval2;

        long   lval1;

        long   lval2;

        boolean numeric = val1 instanceof NumericValueExp;

        if (numeric) {

            if (((NumericValueExp)val1).isLong()) {

                lval1 = ((NumericValueExp)val1).longValue();

                lval2 = ((NumericValueExp)val2).longValue();

                switch (op) {

                case Query.PLUS:

                    return Query.value(lval1 + lval2);

                case Query.TIMES:

                    return Query.value(lval1 * lval2);

                case Query.MINUS:

                    return Query.value(lval1 - lval2);

                case Query.DIV:

                    return Query.value(lval1 / lval2);

                }

            } else {

                dval1 = ((NumericValueExp)val1).doubleValue();

                dval2 = ((NumericValueExp)val2).doubleValue();

                switch (op) {

                case Query.PLUS:

                    return Query.value(dval1 + dval2);

                case Query.TIMES:

                    return Query.value(dval1 * dval2);

                case Query.MINUS:

                    return Query.value(dval1 - dval2);

                case Query.DIV:

                    return Query.value(dval1 / dval2);

                }

            }

        } else {

            sval1 = ((StringValueExp)val1).getValue();

            sval2 = ((StringValueExp)val2).getValue();

            switch (op) {

            case Query.PLUS:

                return new StringValueExp(sval1 + sval2);

            default:

                throw new BadStringOperationException(opString());

            }

        }

        throw new BadBinaryOpValueExpException(this);

    }

    /**

     * Returns the string representing the object

     */

    public String toString()  {

        try {

            return parens(exp1, true) + " " + opString() + " " + parens(exp2, false);

        } catch (BadBinaryOpValueExpException ex) {

            return "invalid expression";

        }

    }

    /*

     * Add parentheses to the given subexpression if necessary to

     * preserve meaning.  Suppose this BinaryOpValueExp is

     * Query.times(Query.plus(Query.attr("A"), Query.attr("B")), Query.attr("C")).

     * Then the original toString() logic would return A + B * C.

     * We check precedences in order to return (A + B) * C, which is the

     * meaning of the ValueExp.

     *

     * We need to add parentheses if the unparenthesized expression would

     * be parsed as a different ValueExp from the original.

     * We cannot omit parentheses even when mathematically

     * the result would be equivalent, because we do not know whether the

     * numeric values will be integer or floating-point.  Addition and

     * multiplication are associative for integers but not always for

     * floating-point.

     *

     * So the rule is that we omit parentheses if the ValueExp

     * is (A op1 B) op2 C and the precedence of op1 is greater than or

     * equal to that of op2; or if the ValueExp is A op1 (B op2 C) and

     * the precedence of op2 is greater than that of op1.  (There are two

     * precedences: that of * and / is greater than that of + and -.)

     * The case of (A op1 B) op2 (C op3 D) applies each rule in turn.

     *

     * The following examples show the rules in action.  On the left,

     * the original ValueExp.  On the right, the string representation.

     *

     * (A + B) + C     A + B + C

     * (A * B) + C     A * B + C

     * (A + B) * C     (A + B) * C

     * (A * B) * C     A * B * C

     * A + (B + C)     A + (B + C)

     * A + (B * C)     A + B * C

     * A * (B + C)     A * (B + C)

     * A * (B * C)     A * (B * C)

     */

    private String parens(ValueExp subexp, boolean left)

    throws BadBinaryOpValueExpException {

        boolean omit;

        if (subexp instanceof BinaryOpValueExp) {

            int subop = ((BinaryOpValueExp) subexp).op;

            if (left)

                omit = (precedence(subop) >= precedence(op));

            else

                omit = (precedence(subop) > precedence(op));

        } else

            omit = true;

        if (omit)

            return subexp.toString();

        else

            return "(" + subexp + ")";

    }

    private int precedence(int xop) throws BadBinaryOpValueExpException {

        switch (xop) {

            case Query.PLUS: case Query.MINUS: return 0;

            case Query.TIMES: case Query.DIV: return 1;

            default:

                throw new BadBinaryOpValueExpException(this);

        }

    }

    private String opString() throws BadBinaryOpValueExpException {

        switch (op) {

        case Query.PLUS:

            return "+";

        case Query.TIMES:

            return "*";

        case Query.MINUS:

            return "-";

        case Query.DIV:

            return "/";

        }

        throw new BadBinaryOpValueExpException(this);

    }

    @Deprecated

    public void setMBeanServer(MBeanServer s) {

        super.setMBeanServer(s);

     }

 }