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/*
 * This file is available under and governed by the GNU General Public
 * License version 2 only, as published by the Free Software Foundation.
 * However, the following notice accompanied the original version of this
 * file:
 *
 * ASM: a very small and fast Java bytecode manipulation framework
 * Copyright (c) 2000-2011 INRIA, France Telecom
 * All rights reserved.
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 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
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 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
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package jdk.internal.org.objectweb.asm.commons;

import jdk.internal.org.objectweb.asm.ClassVisitor;
import jdk.internal.org.objectweb.asm.MethodVisitor;
import jdk.internal.org.objectweb.asm.Opcodes;

A ClassVisitor that merges <clinit> methods into a single one. All the existing <clinit> methods are renamed, and a new one is created, which calls all the renamed methods. 
Author:
Eric Bruneton/**
 * A {@link ClassVisitor} that merges &lt;clinit&gt; methods into a single one. All the existing
 * &lt;clinit&gt; methods are renamed, and a new one is created, which calls all the renamed
 * methods.
 *
 * @author Eric Bruneton
 */
public class StaticInitMerger extends ClassVisitor {

    
The internal name of the visited class. /** The internal name of the visited class. */
    private String owner;

    
The prefix to use to rename the existing <clinit> methods. /** The prefix to use to rename the existing &lt;clinit&gt; methods. */
    private final String renamedClinitMethodPrefix;

    
The number of <clinit> methods visited so far. /** The number of &lt;clinit&gt; methods visited so far. */
    private int numClinitMethods;

    
The MethodVisitor for the merged <clinit> method. /** The MethodVisitor for the merged &lt;clinit&gt; method. */
    private MethodVisitor mergedClinitVisitor;

    
Constructs a new StaticInitMerger. Subclasses must not use this constructor. Instead, they must use the StaticInitMerger(int, String, ClassVisitor) version. 
Params:
prefix – the prefix to use to rename the existing <clinit> methods.
classVisitor – the class visitor to which this visitor must delegate method calls. May be
    null./**
      * Constructs a new {@link StaticInitMerger}. <i>Subclasses must not use this constructor</i>.
      * Instead, they must use the {@link #StaticInitMerger(int, String, ClassVisitor)} version.
      *
      * @param prefix the prefix to use to rename the existing &lt;clinit&gt; methods.
      * @param classVisitor the class visitor to which this visitor must delegate method calls. May be
      *     null.
      */
    public StaticInitMerger(final String prefix, final ClassVisitor classVisitor) {
        this(/* latest api = */ Opcodes.ASM8, prefix, classVisitor);
    }

    
Constructs a new StaticInitMerger. 
Params:
api – the ASM API version implemented by this visitor. Must be one of Opcodes.ASM4, Opcodes.ASM5, Opcodes.ASM6, Opcodes.ASM7 or Opcodes.ASM8.
prefix – the prefix to use to rename the existing <clinit> methods.
classVisitor – the class visitor to which this visitor must delegate method calls. May be
    null./**
      * Constructs a new {@link StaticInitMerger}.
      *
      * @param api the ASM API version implemented by this visitor. Must be one of {@link
      *     Opcodes#ASM4}, {@link Opcodes#ASM5}, {@link Opcodes#ASM6}, {@link Opcodes#ASM7} or {@link
      *     Opcodes#ASM8}.
      * @param prefix the prefix to use to rename the existing &lt;clinit&gt; methods.
      * @param classVisitor the class visitor to which this visitor must delegate method calls. May be
      *     null.
      */
    protected StaticInitMerger(final int api, final String prefix, final ClassVisitor classVisitor) {
        super(api, classVisitor);
        this.renamedClinitMethodPrefix = prefix;
    }

    @Override
    public void visit(
            final int version,
            final int access,
            final String name,
            final String signature,
            final String superName,
            final String[] interfaces) {
        super.visit(version, access, name, signature, superName, interfaces);
        this.owner = name;
    }

    @Override
    public MethodVisitor visitMethod(
            final int access,
            final String name,
            final String descriptor,
            final String signature,
            final String[] exceptions) {
        MethodVisitor methodVisitor;
        if ("<clinit>".equals(name)) {
            int newAccess = Opcodes.ACC_PRIVATE + Opcodes.ACC_STATIC;
            String newName = renamedClinitMethodPrefix + numClinitMethods++;
            methodVisitor = super.visitMethod(newAccess, newName, descriptor, signature, exceptions);

            if (mergedClinitVisitor == null) {
                mergedClinitVisitor = super.visitMethod(newAccess, name, descriptor, null, null);
            }
            mergedClinitVisitor.visitMethodInsn(Opcodes.INVOKESTATIC, owner, newName, descriptor, false);
        } else {
            methodVisitor = super.visitMethod(access, name, descriptor, signature, exceptions);
        }
        return methodVisitor;
    }

    @Override
    public void visitEnd() {
        if (mergedClinitVisitor != null) {
            mergedClinitVisitor.visitInsn(Opcodes.RETURN);
            mergedClinitVisitor.visitMaxs(0, 0);
        }
        super.visitEnd();
    }
}