LongUnaryOperator.java revision 2278037aa1653a32014df55f325879b4fe75fc27 
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25package java.util.function;
26
27import java.util.Objects;
28
29/**
30 * Represents an operation on a single {@code long}-valued operand that produces
31 * a {@code long}-valued result.  This is the primitive type specialization of
32 * {@link UnaryOperator} for {@code long}.
33 *
34 * <p>This is a <a href="package-summary.html">functional interface</a>
35 * whose functional method is {@link #applyAsLong(long)}.
36 *
37 * @see UnaryOperator
38 * @since 1.8
39 */
40@FunctionalInterface
41public interface LongUnaryOperator {
42
43    /**
44     * Applies this operator to the given operand.
45     *
46     * @param operand the operand
47     * @return the operator result
48     */
49    long applyAsLong(long operand);
50
51    /**
52     * Returns a composed operator that first applies the {@code before}
53     * operator to its input, and then applies this operator to the result.
54     * If evaluation of either operator throws an exception, it is relayed to
55     * the caller of the composed operator.
56     *
57     * @param before the operator to apply before this operator is applied
58     * @return a composed operator that first applies the {@code before}
59     * operator and then applies this operator
60     * @throws NullPointerException if before is null
61     *
62     * @see #andThen(LongUnaryOperator)
63     */
64    default LongUnaryOperator compose(LongUnaryOperator before) {
65        Objects.requireNonNull(before);
66        return (long v) -> applyAsLong(before.applyAsLong(v));
67    }
68
69    /**
70     * Returns a composed operator that first applies this operator to
71     * its input, and then applies the {@code after} operator to the result.
72     * If evaluation of either operator throws an exception, it is relayed to
73     * the caller of the composed operator.
74     *
75     * @param after the operator to apply after this operator is applied
76     * @return a composed operator that first applies this operator and then
77     * applies the {@code after} operator
78     * @throws NullPointerException if after is null
79     *
80     * @see #compose(LongUnaryOperator)
81     */
82    default LongUnaryOperator andThen(LongUnaryOperator after) {
83        Objects.requireNonNull(after);
84        return (long t) -> after.applyAsLong(applyAsLong(t));
85    }
86
87    /**
88     * Returns a unary operator that always returns its input argument.
89     *
90     * @return a unary operator that always returns its input argument
91     */
92    static LongUnaryOperator identity() {
93        return t -> t;
94    }
95}
96