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package javax.management;


This class is used by the query-building mechanism to represent binary operations.
@serialinclude
Since:1.5
/** * 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;
@serialThe operator
/** * @serial The operator */
private int op;
@serialThe first value
/** * @serial The first value */
private ValueExp exp1;
@serialThe second value
/** * @serial The second value */
private ValueExp exp2;
Basic Constructor.
/** * Basic Constructor. */
public BinaryOpValueExp() { }
Creates a new BinaryOpValueExp using operator o applied on v1 and v2 values.
/** * 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.
/** * Returns the operator of the value expression. */
public int getOperator() { return op; }
Returns the left value of the value expression.
/** * Returns the left value of the value expression. */
public ValueExp getLeftValue() { return exp1; }
Returns the right value of the value expression.
/** * Returns the right value of the value expression. */
public ValueExp getRightValue() { return exp2; }
Applies the BinaryOpValueExp on a MBean.
Params:
  • name – The name of the MBean on which the BinaryOpValueExp will be applied.
Throws:
Returns: The ValueExp.
/** * 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
/** * 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); } }