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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
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 *
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package java.util.stream;

import java.util.function.ToIntFunction;

/**
 * An enum describing the known shape specializations for stream abstractions.  Each will correspond to
 * a specific subinterface of {@link BaseStream} (e.g., {@code REFERENCE} corresponds to {@code Stream},
 * {@code INT_VALUE} corresponds to {@code IntStream}).  Each may also correspond to specializations of
 * value-handling abstractions such as {@code Spliterator}, {@code Consumer}, etc.
 *
 * @apiNote
 * This enum is used by implementations to determine compatibility between streams and operations (i.e., if the
 * output shape of a stream is compatible with the input shape of the next operation).  It is also used to reduce
 * the code bloat associated with having multiple specialized stream types for primitives by allowing some code
 * to be largely shape-independent.
 *
 * <p>Some APIs require you to specify both a generic type and a stream shape for input or output elements, such as
 * {@link IntermediateOp} which has both generic type parameters for its input and output types, and getters for
 * the input and output shape.  When representing primitive streams in this way, the generic type parameter should
 * correspond to the wrapper type for that primitive type.  Accordingly, the {@code IntermediateOp} implementating
 * {@link Stream#map(ToIntFunction)} would have an output type parameter of {@code Integer} and an output
 * shape of @{code INT_VALUE}.
 * @since 1.8
 */
enum StreamShape {
    REFERENCE,
    INT_VALUE,
    LONG_VALUE,
    DOUBLE_VALUE
}