Instruction.java

/*
 * Copyright 2000-2014 JetBrains s.r.o.
 *
 * 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 org.jetbrains.java.decompiler.code;

import java.io.DataOutputStream;
import java.io.IOException;

public class Instruction implements CodeConstants {

  // *****************************************************************************
  // public fields
  // *****************************************************************************

  public int opcode;

  public int group = CodeConstants.GROUP_GENERAL;

  public boolean wide = false;

  public int bytecode_version = BYTECODE_JAVA_LE_4;

  // *****************************************************************************
  // private fields
  // *****************************************************************************

  private int[] operands = null;

  // *****************************************************************************
  // public methods
  // *****************************************************************************

  public Instruction() {
  }

  public int length() {
    return 1;
  }

  public int operandsCount() {
    return (operands == null) ? 0 : operands.length;
  }

  public int getOperand(int index) {
    return operands[index];
  }

  public Instruction clone() {
    return ConstantsUtil.getInstructionInstance(opcode, wide, group, bytecode_version, operands == null ? null : operands.clone());
  }

  public String toString() {

    String res = wide ? "@wide " : "";
    res += "@" + ConstantsUtil.getName(opcode);

    int len = operandsCount();
    for (int i = 0; i < len; i++) {
      int op = operands[i];
      if (op < 0) {
        res += " -" + Integer.toHexString(-op);
      }
      else {
        res += " " + Integer.toHexString(op);
      }
    }

    return res;
  }

  public boolean canFallthrough() {
    return opcode != opc_goto && opcode != opc_goto_w && opcode != opc_ret &&
           !(opcode >= opc_ireturn && opcode <= opc_return) && opcode != opc_athrow
           && opcode != opc_jsr && opcode != opc_tableswitch && opcode != opc_lookupswitch;
  }

  public boolean equalsInstruction(Instruction instr) {
    if (opcode != instr.opcode || wide != instr.wide
        || operandsCount() != instr.operandsCount()) {
      return false;
    }

    if (operands != null) {
      for (int i = 0; i < operands.length; i++) {
        if (operands[i] != instr.getOperand(i)) {
          return false;
        }
      }
    }

    return true;
  }

  // should be overwritten by subclasses
  public void initInstruction(InstructionSequence seq) {
  }

  // should be overwritten by subclasses
  public void writeToStream(DataOutputStream out, int offset) throws IOException {
    out.writeByte(opcode);
  }

  // *****************************************************************************
  // getter and setter methods
  // *****************************************************************************

  public int[] getOperands() {
    return operands;
  }

  public void setOperands(int[] operands) {
    this.operands = operands;
  }
}