CallSiteDescriptor.java

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/*
   Copyright 2009-2013 Attila Szegedi

   Licensed under both the Apache License, Version 2.0 (the "Apache License")
   and the BSD License (the "BSD License"), with licensee being free to
   choose either of the two at their discretion.

   You may not use this file except in compliance with either the Apache
   License or the BSD License.

   If you choose to use this file in compliance with the Apache License, the
   following notice applies to you:

       You may obtain a copy of the Apache License at

           http://www.apache.org/licenses/LICENSE-2.0

       Unless required by applicable law or agreed to in writing, software
       distributed under the License is distributed on an "AS IS" BASIS,
       WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
       implied. See the License for the specific language governing
       permissions and limitations under the License.

   If you choose to use this file in compliance with the BSD License, the
   following notice applies to you:

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       modification, are permitted provided that the following conditions are
       met:
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         notice, this list of conditions and the following disclaimer.
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package jdk.internal.dynalink;

import java.lang.invoke.MethodHandles.Lookup;
import java.lang.invoke.MethodType;
import jdk.internal.dynalink.support.CallSiteDescriptorFactory;

/**
 * An immutable descriptor of a call site. It is an immutable object that contains all the information about a call
 * site: the class performing the lookups, the name of the method being invoked, and the method signature. The library
 * has a default {@link CallSiteDescriptorFactory} for descriptors that you can use, or you can create your own
 * descriptor classes, especially if you need to add further information (values passed in additional parameters to the
 * bootstrap method) to them. Call site descriptors are used in this library in place of passing a real call site to
 * guarding linkers so they aren't tempted to directly manipulate the call sites. The constructors of built-in
 * {@link RelinkableCallSite} implementations all need a call site descriptor. Even if you create your own call site
 * descriptors consider using {@link CallSiteDescriptorFactory#tokenizeName(String)} in your implementation.
 *
 * @author Attila Szegedi
 */
public interface CallSiteDescriptor {
    /**
     * The index of the name token that will carry the operation scheme prefix (usually, "dyn").
     */
    public static final int SCHEME = 0;
    /**
     * The index of the name token that will usually carry the operation name.
     */

    public static final int OPERATOR=1;
    /**
     * The index of the name token that will usually carry a name of an operand (of a property, method, etc.)
     */

    public static final int NAME_OPERAND=2;

    /**
     * Character used to delimit tokens in an call site name.
     */
    public static final String TOKEN_DELIMITER = ":";

    /**
     * Character used to delimit operation names in a composite operation specification.
     */
    public static final String OPERATOR_DELIMITER = "|";

    /**
     * Returns the number of tokens in the name of the method at the call site. Method names are tokenized with the
     * colon ":" character, i.e. "dyn:getProp:color" would be the name used to describe a method that retrieves the
     * property named "color" on the object it is invoked on.
     * @return the number of tokens in the name of the method at the call site.
     */
    public int getNameTokenCount();

    /**
     * Returns the <i>i<sup>th</sup></i> token in the method name at the call site. Method names are tokenized with the
     * colon ":" character.
     * @param i the index of the token. Must be between 0 (inclusive) and {@link #getNameTokenCount()} (exclusive)
     * @throws IllegalArgumentException if the index is outside the allowed range.
     * @return the <i>i<sup>th</sup></i> token in the method name at the call site. The returned strings are interned.
     */
    public String getNameToken(int i);

    /**
     * Returns the name of the method at the call site. Note that the object internally only stores the tokenized name,
     * and has to reconstruct the full name from tokens on each invocation.
     * @return the name of the method at the call site.
     */
    public String getName();

    /**
     * The type of the method at the call site.
     *
     * @return type of the method at the call site.
     */
    public MethodType getMethodType();

    /**
     * Returns the lookup passed to the bootstrap method.
     * @return the lookup passed to the bootstrap method.
     */
    public Lookup getLookup();

    /**
     * Creates a new call site descriptor from this descriptor, which is identical to this, except it changes the method
     * type.
     *
     * @param newMethodType the new method type
     * @return a new call site descriptor, with the method type changed.
     */
    public CallSiteDescriptor changeMethodType(MethodType newMethodType);

}