src/jdk.dynalink/share/classes/jdk/dynalink/StandardNamespace.java

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 * This file is available under and governed by the GNU General Public
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/*
   Copyright 2016 Attila Szegedi

   Redistribution and use in source and binary forms, with or without
   modification, are permitted provided that the following conditions are
   met:
   * Redistributions of source code must retain the above copyright
     notice, this list of conditions and the following disclaimer.
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     notice, this list of conditions and the following disclaimer in the
     documentation and/or other materials provided with the distribution.
   * Neither the name of the copyright holder nor the names of
     contributors may be used to endorse or promote products derived from
     this software without specific prior written permission.

   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
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*/

package jdk.dynalink;

/**
 * An enumeration of standard namespaces defined by Dynalink.
 * @since 9
 */
public enum StandardNamespace implements Namespace {
    /**
     * Standard namespace for properties of an object.
     */
    PROPERTY,
    /**
     * Standard namespace for elements of a collection object.
     */
    ELEMENT,
    /**
     * Standard namespace for methods of an object. The method objects retrieved
     * through a {@link StandardOperation#GET} on this namespace can be (and where
     * object semantics allows they should be) unbound, that is: not bound to the
     * object they were retrieved through. When they are used with
     * {@link StandardOperation#CALL} an explicit "this" receiver argument is always
     * passed to them. Of course bound methods can be returned if the object semantics
     * requires them and such methods are free to ignore the receiver passed in the
     * {@code CALL} operation or even raise an error when it is different from the one
     * the method is bound to, or exhibit any other behavior their semantics requires
     * in such case.
     */
    METHOD;

    /**
     * If the passed in operation is a {@link NamespaceOperation}, or a
     * {@link NamedOperation} wrapping a {@link NamespaceOperation}, then it
     * returns the first (if any) {@link StandardNamespace} in its namespace
     * list. If the passed operation is not a namespace operation (optionally
     * wrapped in a named operation), or if it doesn't have any standard
     * namespaces in it, returns {@code null}.
     * @param op the operation
     * @return the first standard namespace in the operation's namespace list
     */
    public static StandardNamespace findFirst(final Operation op) {
        for(final Namespace ns: NamespaceOperation.getNamespaces(NamedOperation.getBaseOperation(op))) {
            if (ns instanceof StandardNamespace) {
                return (StandardNamespace)ns;
            }
        }
        return null;
    }
}