src/java.base/share/classes/java/lang/classfile/constantpool/InvokeDynamicEntry.java

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package java.lang.classfile.constantpool;

import java.lang.constant.ConstantDesc;
import java.lang.constant.DynamicCallSiteDesc;
import java.lang.constant.MethodTypeDesc;

import jdk.internal.classfile.impl.AbstractPoolEntry;
import jdk.internal.classfile.impl.Util;

/**
 * Models a {@code CONSTANT_InvokeDynamic_info} structure, or the symbolic
 * reference to a <dfn>{@index "dynamically-computed call site"}</dfn>, in the
 * constant pool of a {@code class} file.
 * <p>
 * The use of a {@code InvokeDynamicEntry} is modeled by a {@link
 * DynamicCallSiteDesc} symbolic descriptor.  It can be obtained from {@link
 * #asSymbol() InvokeDynamicEntry::asSymbol} and converted back to a constant
 * pool entry through {@link ConstantPoolBuilder#invokeDynamicEntry(DynamicCallSiteDesc)
 * ConstantPoolBuilder::invokeDynamicEntry}.
 * <p>
 * An invoke dynamic entry is composite:
 * {@snippet lang=text :
 * // @link substring="InvokeDynamicEntry" target="ConstantPoolBuilder#invokeDynamicEntry(BootstrapMethodEntry, NameAndTypeEntry)" :
 * InvokeDynamicEntry(
 *     BootstrapMethodEntry bootstrap, // @link substring="bootstrap" target="#bootstrap()"
 *     NameAndTypeEntry nameAndType // @link substring="nameAndType" target="#nameAndType()"
 * )
 * }
 * where the {@link #type() type} in the {@code nameAndType} is a {@linkplain
 * #typeSymbol() method descriptor} string.
 *
 * @apiNote
 * A dynamically-computed call site is frequently called a <dfn>{@index "dynamic
 * call site"}</dfn>, or an <dfn>{@index "indy"}</dfn>, from the abbreviation of
 * "invoke dynamic".
 *
 * @see ConstantPoolBuilder#invokeDynamicEntry
 *      ConstantPoolBuilder::invokeDynamicEntry
 * @see DynamicCallSiteDesc
 * @see java.lang.invoke##indyinsn Dynamically-computed call sites
 * @jvms 4.4.10 The {@code CONSTANT_Dynamic_info} and {@code
 *              CONSTANT_InvokeDynamic_info} Structures
 * @since 24
 */
public sealed interface InvokeDynamicEntry
        extends DynamicConstantPoolEntry
        permits AbstractPoolEntry.InvokeDynamicEntryImpl {

    /**
     * {@return a symbolic descriptor for the {@linkplain #type() invocation
     * type} of this dynamic call site}
     */
    default MethodTypeDesc typeSymbol() {
        return Util.methodTypeSymbol(type());
    }

    /**
     * {@return a symbolic descriptor for this dynamic call site}
     *
     * @see ConstantPoolBuilder#invokeDynamicEntry(DynamicCallSiteDesc)
     *      ConstantPoolBuilder::invokeDynamicEntry(DynamicCallSiteDesc)
     */
    default DynamicCallSiteDesc asSymbol() {
        return DynamicCallSiteDesc.of(bootstrap().bootstrapMethod().asSymbol(),
                                      name().stringValue(),
                                      typeSymbol(),
                                      bootstrap().arguments().stream()
                                                 .map(LoadableConstantEntry::constantValue)
                                                 .toArray(ConstantDesc[]::new));
    }
}