//
// Copyright (C) 2006 United States Government as represented by the
// Administrator of the National Aeronautics and Space Administration
// (NASA).  All Rights Reserved.
// 
// This software is distributed under the NASA Open Source Agreement
// (NOSA), version 1.3.  The NOSA has been approved by the Open Source
// Initiative.  See the file NOSA-1.3-JPF at the top of the distribution
// directory tree for the complete NOSA document.
// 
// THE SUBJECT SOFTWARE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY OF ANY
// KIND, EITHER EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING, BUT NOT
// LIMITED TO, ANY WARRANTY THAT THE SUBJECT SOFTWARE WILL CONFORM TO
// SPECIFICATIONS, ANY IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR
// A PARTICULAR PURPOSE, OR FREEDOM FROM INFRINGEMENT, ANY WARRANTY THAT
// THE SUBJECT SOFTWARE WILL BE ERROR FREE, OR ANY WARRANTY THAT
// DOCUMENTATION, IF PROVIDED, WILL CONFORM TO THE SUBJECT SOFTWARE.
//
package gov.nasa.jpf.jvm.bytecode;

import java.util.function.BiFunction;
import cmu.conditional.Conditional;
import cmu.conditional.One;
import de.fosd.typechef.featureexpr.FeatureExpr;
import gov.nasa.jpf.jvm.JVMInstruction;
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 JVMInstruction {
	private String type;

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

	public Conditional<Instruction> execute(FeatureExpr ctx, final 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();
			}
		}

		final StackFrame frame = ti.getModifiableTopFrame();
		Conditional<Integer> objref = frame.pop(ctx);
		return objref.mapf(ctx, new BiFunction<FeatureExpr, Integer, Conditional<Instruction>>() {

			@Override
			public Conditional<Instruction> apply(FeatureExpr ctx, Integer objref) {
				if (objref == MJIEnv.NULL) {
					frame.push(ctx, One.valueOf(0));
				} else if (ti.getElementInfo(objref).instanceOf(type)) {
					frame.push(ctx, One.valueOf(1));
				} else {
					frame.push(ctx, One.valueOf(0));
				}

				return getNext(ctx, ti);
			}

		});
	}

	public String getType() {
		return type;
	}

	public int getLength() {
		return 3; // opcode, index1, index2
	}

	public int getByteCode() {
		return 0xC1;
	}

	public void accept(InstructionVisitor insVisitor) {
		insVisitor.visit(this);
	}
}