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Truffle is a multi-language framework for executing dynamic languages that achieves high performance when combined with Graal.
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/*
 * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * 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,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
package com.oracle.truffle.api.interop;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

import com.oracle.truffle.api.TruffleLanguage;
import com.oracle.truffle.api.nodes.Node;

/**
 * Annotation to put on your node to simplify handling of incoming inter-operability {@link Message
 * messages}.
 *
 * This class contains the node implementations for all messages that the receiver object should
 * resolve. Use {@link Resolve} to annotate {@link Node} implementations of messages. Those messages
 * for which no {@link Resolve} is provided are either left unsupported, or in case of
 * HAS/IS messages they get a default boolean value depending on presence of
 * corresponding messages. E.g. HAS_SIZE is true if and only if GET_SIZE
 * is provided, IS_EXECUTABLE is true if and only if EXECUTE is provided,
 * etc. If objects support some messages conditionally, they should provide their own implementation
 * of HAS/IS messages. Elements in the super class that are annotated with
 * {@link Resolve} will be ignored. For example:
 *
 * {@link com.oracle.truffle.api.dsl.test.interop.Snippets.ExampleTruffleObjectMR}
 *
 * The receiver object needs to implement a static method isInstance, which checks if a
 * given foreign object is an instance of the given receiver type and can therefore be accessed by
 * this node. For example:
 *
 * {@link com.oracle.truffle.api.dsl.test.interop.Snippets.ExampleTruffleObject#isInstanceCheck}
 *
 * Alternatively, one can also define a language check node (see {@link CanResolve}.
 *
 * From this class a {@link ForeignAccess} will be generated. The receiver object can then return a
 * singleton instance of this access. For example: 

 *
 * {@link com.oracle.truffle.api.dsl.test.interop.Snippets.ExampleTruffleObject#getForeignAccessMethod}
 *
 * @since 0.13
 */
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.SOURCE)
public @interface MessageResolution {

    /**
     * The receiver object class that this message implementation belongs to.
     *
     * An annotation processor generates a {@link ForeignAccess} class, which the
     * {@link TruffleObject} can use to implement {@link TruffleObject#getForeignAccess()}.
     *
     * @return class of the receiver object
     *
     * @since 0.13
     */
    Class receiverType();

    /**
     * The language the message implementation belongs to.
     *
     * @return class of the language object
     *
     * @since 0.13
     * @deprecated in 0.25 without replacement
     */
    @Deprecated
    Class language() default TruffleLanguage.class;

}