jdk/src/java.base/share/classes/java/lang/classfile/CompoundElement.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
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 * accompanied this code).
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package java.lang.classfile;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.Spliterator;
import java.util.Spliterators;
import java.util.function.Consumer;
import java.util.stream.Stream;
import java.util.stream.StreamSupport;

import jdk.internal.classfile.components.ClassPrinter;

/**
 * A {@link ClassFileElement} that has complex structure defined in terms of
 * other classfile elements, such as a method, field, method body, or entire
 * class.  When encountering a {@linkplain CompoundElement}, clients have the
 * option to treat the element as a single entity (e.g., an entire method)
 * or to traverse the contents of that element with the methods in this class
 * (e.g., {@link #forEach(Consumer)}, etc.)
 * @param <E> the element type
 *
 * @sealedGraph
 * @since 24
 */
public sealed interface CompoundElement<E extends ClassFileElement>
        extends ClassFileElement, Iterable<E>
        permits ClassModel, CodeModel, FieldModel, MethodModel, jdk.internal.classfile.impl.AbstractUnboundModel {
    /**
     * Invoke the provided handler with each element contained in this
     * compound element
     * @param consumer the handler
     */
    @Override
    void forEach(Consumer<? super E> consumer);

    /**
     * {@return an {@link Iterator} describing all the elements contained in this
     * compound element}
     */
    @Override
    default Iterator<E> iterator() {
        return elementList().iterator();
    }

    /**
     * {@return a {@link Stream} containing all the elements contained in this
     * compound element}
     */
    default Stream<E> elementStream() {
        return StreamSupport.stream(Spliterators.spliteratorUnknownSize(
                                            iterator(),
                                            Spliterator.IMMUTABLE | Spliterator.NONNULL | Spliterator.ORDERED),
                                    false);
    }

    /**
     * {@return an {@link List} containing all the elements contained in this
     * compound element}
     */
    default List<E> elementList() {
        List<E> list = new ArrayList<>();
        forEach(new Consumer<>() {
            @Override
            public void accept(E e) {
                list.add(e);
            }
        });
        return Collections.unmodifiableList(list);
    }

    /**
     * {@return a text representation of the compound element and its contents for debugging purposes}
     *
     * The format, structure and exact contents of the returned string are not specified and may change at any time in the future.
     */
    default String toDebugString() {
        StringBuilder text = new StringBuilder();
        ClassPrinter.toYaml(this, ClassPrinter.Verbosity.TRACE_ALL, text::append);
        return text.toString();
    }
}