/*
 * Copyright (C) 2014, United States Government, as represented by the
 * Administrator of the National Aeronautics and Space Administration.
 * All rights reserved.
 *
 * The Java Pathfinder core (jpf-core) platform is 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 gov.nasa.jpf.jvm.bytecode;

import gov.nasa.jpf.vm.Instruction;
import gov.nasa.jpf.vm.LoadOnJPFRequired;
import gov.nasa.jpf.vm.MJIEnv;
import gov.nasa.jpf.vm.StackFrame;
import gov.nasa.jpf.vm.ThreadInfo;
import gov.nasa.jpf.vm.Types;


/**
 * Determine if object is of given type
 * ..., objectref => ..., result
 */
public class INSTANCEOF extends Instruction implements JVMInstruction {
  private String type;


  /**
   * typeName is of a/b/C notation
   */
  public INSTANCEOF (String typeName){
    type = Types.getTypeSignature(typeName, false);
  }

  @Override
  public Instruction execute (ThreadInfo ti) {
    if(Types.isReferenceSignature(type)) {
      String t;
      if(Types.isArray(type)) {
        // retrieve the component terminal
        t = Types.getComponentTerminal(type);
      } else {
        t = type;
      }

      // resolve the referenced class
      try {
        ti.resolveReferencedClass(t);
      } catch(LoadOnJPFRequired lre) {
        return ti.getPC();
      }
    }

    StackFrame frame = ti.getModifiableTopFrame();
    int objref = frame.pop();

    if (objref == MJIEnv.NULL) {
      frame.push(0);
    } else if (ti.getElementInfo(objref).instanceOf(type)) {
      frame.push(1);
    } else {
      frame.push(0);
    }

    return getNext(ti);
  }
  
  public String getType() {
	  return type;
  }

  @Override
  public int getLength() {
    return 3; // opcode, index1, index2
  }
  
  @Override
  public int getByteCode () {
    return 0xC1;
  }
  
  @Override
  public void accept(JVMInstructionVisitor insVisitor) {
	  insVisitor.visit(this);
  }
}