// 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.objectweb.asm.benchmarks;

import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;

/**
 * A "Hello World!" class generator using the ASM library.
 *
 * @author Eric Bruneton
 */
public class AsmGenerator extends Generator {

  @Override
  public String getVersion() {
    for (int i = 6; i >= 4; --i) {
      try {
        String version = "ASM" + i;
        if (Opcodes.class.getField(version) != null) {
          return version;
        }
      } catch (NoSuchFieldException e) {
        continue;
      }
    }
    return "";
  }

  @Override
  public byte[] generateClass() {
    ClassWriter classWriter = new ClassWriter(ClassWriter.COMPUTE_MAXS);

    classWriter.visit(
        Opcodes.V1_1, Opcodes.ACC_PUBLIC, "HelloWorld", null, "java/lang/Object", null);
    classWriter.visitSource("HelloWorld.java", null);

    MethodVisitor methodVisitor =
        classWriter.visitMethod(Opcodes.ACC_PUBLIC, "<init>", "()V", null, null);
    methodVisitor.visitVarInsn(Opcodes.ALOAD, 0);
    methodVisitor.visitMethodInsn(Opcodes.INVOKESPECIAL, "java/lang/Object", "<init>", "()V");
    methodVisitor.visitInsn(Opcodes.RETURN);
    methodVisitor.visitMaxs(0, 0);
    methodVisitor.visitEnd();

    methodVisitor =
        classWriter.visitMethod(
            Opcodes.ACC_PUBLIC + Opcodes.ACC_STATIC, "main", "([Ljava/lang/String;)V", null, null);
    methodVisitor.visitFieldInsn(
        Opcodes.GETSTATIC, "java/lang/System", "out", "Ljava/io/PrintStream;");
    methodVisitor.visitLdcInsn("Hello world!");
    methodVisitor.visitMethodInsn(
        Opcodes.INVOKEVIRTUAL, "java/io/PrintStream", "println", "(Ljava/lang/String;)V");
    methodVisitor.visitInsn(Opcodes.RETURN);
    methodVisitor.visitMaxs(0, 0);
    methodVisitor.visitEnd();

    return classWriter.toByteArray();
  }
}
