/*
 * Copyright (c) 2022, 2024, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
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);
    }
}