001/***
002 * ASM: a very small and fast Java bytecode manipulation framework
003 * Copyright (c) 2000-2011 INRIA, France Telecom
004 * All rights reserved.
005 *
006 * Redistribution and use in source and binary forms, with or without
007 * modification, are permitted provided that the following conditions
008 * are met:
009 * 1. Redistributions of source code must retain the above copyright
010 *    notice, this list of conditions and the following disclaimer.
011 * 2. Redistributions in binary form must reproduce the above copyright
012 *    notice, this list of conditions and the following disclaimer in the
013 *    documentation and/or other materials provided with the distribution.
014 * 3. Neither the name of the copyright holders nor the names of its
015 *    contributors may be used to endorse or promote products derived from
016 *    this software without specific prior written permission.
017 *
018 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
019 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
020 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
021 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
022 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
023 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
024 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
025 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
026 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
027 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
028 * THE POSSIBILITY OF SUCH DAMAGE.
029 */
030package io.ebean.enhance.asm.commons;
031
032import io.ebean.enhance.asm.ClassVisitor;
033import io.ebean.enhance.asm.MethodVisitor;
034import io.ebean.enhance.asm.Opcodes;
035
036/**
037 * A {@link ClassVisitor} that merges clinit methods into a single one.
038 * 
039 * @author Eric Bruneton
040 */
041public class StaticInitMerger extends ClassVisitor {
042
043    private String name;
044
045    private MethodVisitor clinit;
046
047    private final String prefix;
048
049    private int counter;
050
051    public StaticInitMerger(final String prefix, final ClassVisitor cv) {
052        this(Opcodes.ASM6, prefix, cv);
053    }
054
055    protected StaticInitMerger(final int api, final String prefix,
056            final ClassVisitor cv) {
057        super(api, cv);
058        this.prefix = prefix;
059    }
060
061    @Override
062    public void visit(final int version, final int access, final String name,
063            final String signature, final String superName,
064            final String[] interfaces) {
065        cv.visit(version, access, name, signature, superName, interfaces);
066        this.name = name;
067    }
068
069    @Override
070    public MethodVisitor visitMethod(final int access, final String name,
071                                     final String desc, final String signature, final String[] exceptions) {
072        MethodVisitor mv;
073        if ("<clinit>".equals(name)) {
074            int a = Opcodes.ACC_PRIVATE + Opcodes.ACC_STATIC;
075            String n = prefix + counter++;
076            mv = cv.visitMethod(a, n, desc, signature, exceptions);
077
078            if (clinit == null) {
079                clinit = cv.visitMethod(a, name, desc, null, null);
080            }
081            clinit.visitMethodInsn(Opcodes.INVOKESTATIC, this.name, n, desc,
082                    false);
083        } else {
084            mv = cv.visitMethod(access, name, desc, signature, exceptions);
085        }
086        return mv;
087    }
088
089    @Override
090    public void visitEnd() {
091        if (clinit != null) {
092            clinit.visitInsn(Opcodes.RETURN);
093            clinit.visitMaxs(0, 0);
094        }
095        cv.visitEnd();
096    }
097}