StreamShape.java revision 603700058363f21b7b2ecae9c44e9617183ab3f9 
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25package java.util.stream;
26
27/**
28 * An enum describing the known shape specializations for stream abstractions.
29 * Each will correspond to a specific subinterface of {@link BaseStream}
30 * (e.g., {@code REFERENCE} corresponds to {@code Stream}, {@code INT_VALUE}
31 * corresponds to {@code IntStream}).  Each may also correspond to
32 * specializations of value-handling abstractions such as {@code Spliterator},
33 * {@code Consumer}, etc.
34 *
35 * @apiNote
36 * This enum is used by implementations to determine compatibility between
37 * streams and operations (i.e., if the output shape of a stream is compatible
38 * with the input shape of the next operation).
39 *
40 * <p>Some APIs require you to specify both a generic type and a stream shape
41 * for input or output elements, such as {@link TerminalOp} which has both
42 * generic type parameters for its input types, and a getter for the
43 * input shape.  When representing primitive streams in this way, the
44 * generic type parameter should correspond to the wrapper type for that
45 * primitive type.
46 *
47 * @since 1.8
48 * @hide Visible for CTS testing only (OpenJDK8 tests).
49 */
50public enum StreamShape {
51    /**
52     * The shape specialization corresponding to {@code Stream} and elements
53     * that are object references.
54     */
55    REFERENCE,
56    /**
57     * The shape specialization corresponding to {@code IntStream} and elements
58     * that are {@code int} values.
59     */
60    INT_VALUE,
61    /**
62     * The shape specialization corresponding to {@code LongStream} and elements
63     * that are {@code long} values.
64     */
65    LONG_VALUE,
66    /**
67     * The shape specialization corresponding to {@code DoubleStream} and
68     * elements that are {@code double} values.
69     */
70    DOUBLE_VALUE
71}
72