001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018package org.apache.commons.rng.sampling;
019
020import java.util.stream.Stream;
021
022/**
023 * Sampler that generates values of a specified type.
024 *
025 * @param <T> Type of the sample.
026 * @since 1.4
027 */
028@FunctionalInterface
029public interface ObjectSampler<T> {
030    /**
031     * Create an object sample.
032     *
033     * @return a sample.
034     */
035    T sample();
036
037    /**
038     * Returns an effectively unlimited stream of object sample values.
039     *
040     * <p>The default implementation produces a sequential stream that repeatedly
041     * calls {@link #sample sample}().
042     *
043     * @return a stream of object values.
044     * @since 1.5
045     */
046    default Stream<T> samples() {
047        return Stream.generate(this::sample).sequential();
048    }
049
050    /**
051     * Returns a stream producing the given {@code streamSize} number of object
052     * sample values.
053     *
054     * <p>The default implementation produces a sequential stream that repeatedly
055     * calls {@link #sample sample}(); the stream is limited to the given {@code streamSize}.
056     *
057     * @param streamSize Number of values to generate.
058     * @return a stream of object values.
059     * @since 1.5
060     */
061    default Stream<T> samples(long streamSize) {
062        return samples().limit(streamSize);
063    }
064}