1/*
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15 * accompanied this code).
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24 */
25
26package javax.management;
27
28
29/**
30 * Represents values that can be passed as arguments to
31 * relational expressions. Strings, numbers, attributes are valid values
32 * and should be represented by implementations of <CODE>ValueExp</CODE>.
33 *
34 * @since 1.5
35 */
36/*
37  We considered generifying this interface as ValueExp<T>, where T is
38  the Java type that this expression generates.  This allows some additional
39  checking in the various methods of the Query class, but in practice
40  not much.  Typically you have something like
41  Query.lt(Query.attr("A"), Query.value(5)).  We can arrange for Query.value
42  to have type ValueExp<Integer> (or maybe ValueExp<Long> or ValueExp<Number>)
43  but for Query.attr we can't do better than ValueExp<?> or plain ValueExp.
44  So even though we could define Query.lt as:
45  QueryExp <T> lt(ValueExp<T> v1, ValueExp<T> v2)
46  and thus prevent comparing a
47  number against a string, in practice the first ValueExp will almost always
48  be a Query.attr so this check serves no purpose.  You would have to
49  write Query.<Number>attr("A"), for example, which would be awful.  And,
50  if you wrote Query.<Integer>attr("A") you would then discover that you
51  couldn't compare it against Query.value(5) if the latter is defined as
52  ValueExp<Number>, or against Query.value(5L) if it is defined as
53  ValueExp<Integer>.
54
55  Worse, for Query.in we would like to define:
56  QueryExp <T> in(ValueExp<T> val, ValueExp<T>[] valueList)
57  but this is unusable because you cannot write
58  "new ValueExp<Integer>[] {...}" (the compiler forbids it).
59
60  The few mistakes you might catch with this generification certainly
61  wouldn't justify the hassle of modifying user code to get the checks
62  to be made and the "unchecked" warnings that would arise if it
63  wasn't so modified.
64
65  We could reconsider this if the Query methods were augmented, for example
66  with:
67  AttributeValueExp<Number> numberAttr(String name);
68  AttributeValueExp<String> stringAttr(String name);
69  AttributeValueExp<Boolean> booleanAttr(String name);
70  QueryExp <T> in(ValueExp<T> val, Set<ValueExp<T>> valueSet).
71  But it's not really clear what numberAttr should do if it finds that the
72  attribute is not in fact a Number.
73 */
74public interface ValueExp extends java.io.Serializable {
75
76    /**
77     * Applies the ValueExp on a MBean.
78     *
79     * @param name The name of the MBean on which the ValueExp will be applied.
80     *
81     * @return  The <CODE>ValueExp</CODE>.
82     *
83     * @throws BadStringOperationException when an invalid string
84     * operation is passed to a method for constructing a query
85     * @throws BadBinaryOpValueExpException when an invalid expression
86     * is passed to a method for constructing a query
87     * @throws BadAttributeValueExpException when an invalid MBean
88     * attribute is passed to a query constructing method
89     * @throws InvalidApplicationException when an invalid apply is attempted
90     */
91    public ValueExp apply(ObjectName name)
92            throws BadStringOperationException, BadBinaryOpValueExpException,
93                   BadAttributeValueExpException, InvalidApplicationException;
94
95    /**
96     * Sets the MBean server on which the query is to be performed.
97     *
98     * @param s The MBean server on which the query is to be performed.
99     *
100     * @deprecated This method is not needed because a
101     * <code>ValueExp</code> can access the MBean server in which it
102     * is being evaluated by using {@link QueryEval#getMBeanServer()}.
103     */
104    @Deprecated
105    public  void setMBeanServer(MBeanServer s) ;
106}
107