plugins/org.eclipse.persistence.asm/src/org/eclipse/persistence/internal/libraries/asm/commons/StaticInitMerger.java

/***
 * ASM: a very small and fast Java bytecode manipulation framework
 * Copyright (c) 2000-2011 INRIA, France Telecom
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the copyright holders nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.eclipse.persistence.internal.libraries.asm.commons;

import org.eclipse.persistence.internal.libraries.asm.ClassVisitor;
import org.eclipse.persistence.internal.libraries.asm.MethodVisitor;
import org.eclipse.persistence.internal.libraries.asm.Opcodes;

/**
 * A {@link ClassVisitor} that merges clinit methods into a single one.
 * 
 * @author Eric Bruneton
 */
public class StaticInitMerger extends ClassVisitor {

    private String name;

    private MethodVisitor clinit;

    private final String prefix;

    private int counter;

    public StaticInitMerger(final String prefix, final ClassVisitor cv) {
        this(Opcodes.ASM6, prefix, cv);
    }

    protected StaticInitMerger(final int api, final String prefix,
            final ClassVisitor cv) {
        super(api, cv);
        this.prefix = prefix;
    }

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

    @Override
    public MethodVisitor visitMethod(final int access, final String name,
            final String desc, final String signature, final String[] exceptions) {
        MethodVisitor mv;
        if ("<clinit>".equals(name)) {
            int a = Opcodes.ACC_PRIVATE + Opcodes.ACC_STATIC;
            String n = prefix + counter++;
            mv = cv.visitMethod(a, n, desc, signature, exceptions);

            if (clinit == null) {
                clinit = cv.visitMethod(a, name, desc, null, null);
            }
            clinit.visitMethodInsn(Opcodes.INVOKESTATIC, this.name, n, desc,
                    false);
        } else {
            mv = cv.visitMethod(access, name, desc, signature, exceptions);
        }
        return mv;
    }

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