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ProGuardCORE is a free library to read, analyze, modify, and write Java class files.

There is a newer version: 9.1.6

/*
 * ProGuardCORE -- library to process Java bytecode.
 *
 * Copyright (c) 2002-2020 Guardsquare NV
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package proguard.classfile.editor;

import proguard.classfile.*;
import proguard.classfile.attribute.CodeAttribute;
import proguard.classfile.instruction.*;
import proguard.classfile.instruction.visitor.InstructionVisitor;

/**
 * This {@link InstructionVisitor} adds all instructions that it visits to the given target code
 * attribute.
 *
 * @author Eric Lafortune
 */
public class InstructionAdder implements InstructionVisitor {
  private final ConstantAdder constantAdder;
  private final CodeAttributeComposer codeAttributeComposer;

  /** Creates a new InstructionAdder that will copy classes into the given target code attribute. */
  public InstructionAdder(ProgramClass targetClass, CodeAttributeComposer targetComposer) {
    constantAdder = new ConstantAdder(targetClass);
    codeAttributeComposer = targetComposer;
  }

  // Implementations for InstructionVisitor.

  public void visitAnyInstruction(
      Clazz clazz,
      Method method,
      CodeAttribute codeAttribute,
      int offset,
      Instruction instruction) {
    // Add the instruction.
    codeAttributeComposer.appendInstruction(offset, instruction);
  }

  public void visitConstantInstruction(
      Clazz clazz,
      Method method,
      CodeAttribute codeAttribute,
      int offset,
      ConstantInstruction constantInstruction) {
    // Create a copy of the instruction.
    Instruction newConstantInstruction =
        new ConstantInstruction(
            constantInstruction.opcode,
            constantAdder.addConstant(clazz, constantInstruction.constantIndex),
            constantInstruction.constant);

    // Add the instruction.
    codeAttributeComposer.appendInstruction(offset, newConstantInstruction);
  }
}