src/java.base/share/classes/java/lang/classfile/instruction/LineNumber.java

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package java.lang.classfile.instruction;

import java.lang.classfile.ClassFile;
import java.lang.classfile.CodeBuilder;
import java.lang.classfile.CodeElement;
import java.lang.classfile.CodeModel;
import java.lang.classfile.PseudoInstruction;
import java.lang.classfile.attribute.CodeAttribute;
import java.lang.classfile.attribute.LineNumberInfo;
import java.lang.classfile.attribute.LineNumberTableAttribute;

import jdk.internal.classfile.impl.LineNumberImpl;

/**
 * A pseudo-instruction which indicates the code for a given line number starts
 * after the current position in a {@link CodeAttribute Code} attribute.  This
 * models a single entry in the {@link LineNumberTableAttribute LineNumberTable}
 * attribute.  Delivered as a {@link CodeElement} during traversal of the
 * elements of a {@link CodeModel}, according to the setting of the {@link
 * ClassFile.LineNumbersOption} option.
 * <p>
 * A line number entry is composite:
 * {@snippet lang=text :
 * // @link substring="LineNumber" target="#of" :
 * LineNumber(int line) // @link substring="int line" target="#line"
 * }
 * <p>
 * Another model, {@link LineNumberInfo}, also models a line number entry; it
 * has no dependency on a {@code CodeModel} and represents of bci values as
 * {@code int}s instead of order of pseudo-instructions in the elements of a
 * {@code CodeModel}, and is used as components of a {@link LineNumberTableAttribute}.
 *
 * @apiNote
 * Line numbers are represented with custom pseudo-instructions to avoid using
 * labels, which usually indicate branching targets for the control flow.
 *
 * @see LineNumberInfo
 * @see CodeBuilder#lineNumber CodeBuilder::lineNumber
 * @see ClassFile.LineNumbersOption
 * @since 24
 */
public sealed interface LineNumber extends PseudoInstruction
        permits LineNumberImpl {

    /**
     * {@return the line number}
     */
    int line();

    /**
     * {@return a line number pseudo-instruction}
     *
     * @param line the line number
     */
    static LineNumber of(int line) {
        return LineNumberImpl.of(line);
    }
}