/**
 * Copyright (C) 2010-2017 Gordon Fraser, Andrea Arcuri and EvoSuite
 * contributors
 *
 * This file is part of EvoSuite.
 *
 * EvoSuite is free software: you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation, either version 3.0 of the License, or
 * (at your option) any later version.
 *
 * EvoSuite is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with EvoSuite. If not, see <http://www.gnu.org/licenses/>.
 */
package org.evosuite.symbolic.vm;

import java.lang.reflect.Member;

import org.objectweb.asm.Type;

/**
 * Invocation frame.
 * 
 * @author csallner@uta.edu (Christoph Csallner)
 */
public abstract class Frame {

	/**
	 * The last method we invoked is instrumented. This means we invoked some
	 * code that is neither native nor defined by an uninstrumented JDK class.
	 */
	private boolean weInvokedInstrumentedCode = true;

	/**
	 * @return the last method invoked is instrumented, because it is neither
	 *         native nor defined by an uninstrumented JDK class, etc.
	 */
	boolean weInvokedInstrumentedCode() {
		return weInvokedInstrumentedCode;
	}

	/**
	 * The next call is to an instrumented method. The called method is neither
	 * native, nor defined by an uninstrumented JDK class, etc.
	 * <p>
	 * 
	 * Usage: This method has to be called just before any
	 * method/constructor/clinit call.
	 */
	public void invokeInstrumentedCode(boolean b) {
		weInvokedInstrumentedCode = b;
	}

	/**
	 * The last method invoked by this frame needs a "this" receiver reference,
	 * i.e., is an instance method or constructor.
	 */
	boolean invokeNeedsThis;

	/**
	 * Operand stack
	 */
	public final OperandStack operandStack = new OperandStack();

	/**
	 * List of local variables
	 */
	final LocalsTable localsTable;

	/**
	 * Constructor
	 */
	protected Frame(int maxLocals) {
		localsTable = new LocalsTable(maxLocals);
	}

	public abstract Member getMember();

	/**
	 * Without the "this" receiver instance parameter
	 */
	public abstract int getNrFormalParameters();

	public abstract int getNrFormalParametersTotal();

	/**
	 * Dispose operands we passed to called method.
	 * 
	 * //@param nrFormalParameters without "this" receiver instance parameter
	 * 
	 * @param nrFormalParameters
	 *            with "this" receiver instance parameter
	 */
	private void disposeOperands(int nrFormalParameters) {
		for (int i = 0; i < nrFormalParameters; i++)
			operandStack.popOperand();
	}

	/**
	 * We invoked some other method or constructor. Now we want to discard the
	 * parameters we used for this call from our operand stack.
	 */
	void disposeMethInvokeArgs(String methDesc) {
		disposeOperands(Type.getArgumentTypes(methDesc).length);
		if (invokeNeedsThis)
			operandStack.popOperand();
	}

	/**
	 * Dispose the parameters we needed to invoke frame (of instrumented
	 * method).
	 */
	void disposeMethInvokeArgs(Frame frame) {
		disposeOperands(frame.getNrFormalParametersTotal());
	}

	@Override
	public String toString() {
		return getMember().getName() + "--" + operandStack.toString(); //$NON-NLS-1$
	}
}