src/java.base/share/classes/java/lang/classfile/attribute/CompilationIDAttribute.java

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package java.lang.classfile.attribute;

import java.lang.classfile.Attribute;
import java.lang.classfile.AttributeMapper;
import java.lang.classfile.AttributeMapper.AttributeStability;
import java.lang.classfile.Attributes;
import java.lang.classfile.ClassElement;
import java.lang.classfile.constantpool.Utf8Entry;

import jdk.internal.classfile.impl.BoundAttribute;
import jdk.internal.classfile.impl.TemporaryConstantPool;
import jdk.internal.classfile.impl.UnboundAttribute;

/**
 * Models the {@link Attributes#compilationId() CompilationID} attribute, which
 * records the compilation time of the {@code class} file.
 * <p>
 * This attribute only appears on classes, and does not permit {@linkplain
 * AttributeMapper#allowMultiple multiple instances} in a class.  It has a
 * data dependency on the {@linkplain AttributeStability#CP_REFS constant pool}.
 * <p>
 * This attribute is not predefined in the Java SE Platform.  This is a
 * JDK-specific nonstandard attribute produced by the reference implementation
 * of the system Java compiler, defined by the {@code jdk.compiler} module.
 *
 * @see Attributes#compilationId()
 * @see CharacterRangeTableAttribute
 * @see SourceIDAttribute
 * @since 24
 */
public sealed interface CompilationIDAttribute
        extends Attribute<CompilationIDAttribute>, ClassElement
        permits BoundAttribute.BoundCompilationIDAttribute,
                UnboundAttribute.UnboundCompilationIDAttribute {

    /**
     * {@return the compilation ID}  The compilation ID is the string value of
     * {@link System#currentTimeMillis()} when the {@code class} file is generated.
     */
    Utf8Entry compilationId();

    /**
     * {@return a {@code CompilationID} attribute}
     * @param id the compilation ID
     */
    static CompilationIDAttribute of(Utf8Entry id) {
        return new UnboundAttribute.UnboundCompilationIDAttribute(id);
    }

    /**
     * {@return a {@code CompilationID} attribute}
     * @param id the compilation ID
     */
    static CompilationIDAttribute of(String id) {
        return new UnboundAttribute.UnboundCompilationIDAttribute(TemporaryConstantPool.INSTANCE.utf8Entry(id));
    }
}