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      1 /*
      2  * Copyright (c) 2012, 2013, 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 /**
     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  */
     50 public 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