1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.rng.sampling.distribution;
18
19 import java.util.stream.DoubleStream;
20
21 /**
22 * Sampler that generates values of type {@code double}.
23 *
24 * @since 1.0
25 */
26 @FunctionalInterface
27 public interface ContinuousSampler {
28 /**
29 * Creates a {@code double} sample.
30 *
31 * @return a sample.
32 */
33 double sample();
34
35 /**
36 * Returns an effectively unlimited stream of {@code double} sample values.
37 *
38 * <p>The default implementation produces a sequential stream that repeatedly
39 * calls {@link #sample sample}().
40 *
41 * @return a stream of {@code double} values.
42 * @since 1.5
43 */
44 default DoubleStream samples() {
45 return DoubleStream.generate(this::sample).sequential();
46 }
47
48 /**
49 * Returns a stream producing the given {@code streamSize} number of {@code double}
50 * sample values.
51 *
52 * <p>The default implementation produces a sequential stream that repeatedly
53 * calls {@link #sample sample}(); the stream is limited to the given {@code streamSize}.
54 *
55 * @param streamSize Number of values to generate.
56 * @return a stream of {@code double} values.
57 * @since 1.5
58 */
59 default DoubleStream samples(long streamSize) {
60 return samples().limit(streamSize);
61 }
62 }