1 /* 2 * Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 package java.util.stream; 26 27 import java.util.function.ToIntFunction; 28 29 /** 30 * An enum describing the known shape specializations for stream abstractions. Each will correspond to 31 * a specific subinterface of {@link BaseStream} (e.g., {@code REFERENCE} corresponds to {@code Stream}, 32 * {@code INT_VALUE} corresponds to {@code IntStream}). Each may also correspond to specializations of 33 * value-handling abstractions such as {@code Spliterator}, {@code Consumer}, etc. 34 * 35 * @apiNote 36 * This enum is used by implementations to determine compatibility between streams and operations (i.e., if the 37 * output shape of a stream is compatible with the input shape of the next operation). It is also used to reduce 38 * the code bloat associated with having multiple specialized stream types for primitives by allowing some code 39 * to be largely shape-independent. 40 * 41 * <p>Some APIs require you to specify both a generic type and a stream shape for input or output elements, such as 42 * {@link IntermediateOp} which has both generic type parameters for its input and output types, and getters for 43 * the input and output shape. When representing primitive streams in this way, the generic type parameter should 44 * correspond to the wrapper type for that primitive type. Accordingly, the {@code IntermediateOp} implementating 45 * {@link Stream#map(ToIntFunction)} would have an output type parameter of {@code Integer} and an output 46 * shape of @{code INT_VALUE}. 47 * @since 1.8 48 */ 49 enum StreamShape { 50 REFERENCE, 51 INT_VALUE, 52 LONG_VALUE, 53 DOUBLE_VALUE 54 }