/*
 * Copyright  2000-2004 The Apache Software Foundation
 *
 *  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.apache.bcel.generic;

import java.io.DataOutputStream;
import java.io.IOException;
import org.apache.bcel.util.ByteSequence;

/**
 * RET - Return from subroutine
 * 
 * <PRE>
 * Stack: ... -&gt; ...
 * </PRE>
 * 
 * @version $Id: RET.java 386056 2006-03-15 11:31:56Z tcurdt $
 * @author <A HREF="mailto:m.dahm@gmx.de">M. Dahm</A>
 */
public class RET extends Instruction implements IndexedInstruction,
		TypedInstruction {

	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;
	private boolean wide;
	private int index; // index to local variable containg the return address

	/**
	 * Empty constructor needed for the Class.newInstance() statement in
	 * Instruction.readInstruction(). Not to be used otherwise.
	 */
	RET() {
	}

	public RET(int index) {
		super(org.apache.bcel.Constants.RET, (short) 2);
		setIndex(index); // May set wide as side effect
	}

	/**
	 * Dump instruction as byte code to stream out.
	 * 
	 * @param out
	 *            Output stream
	 */
	@Override
	public void dump(DataOutputStream out) throws IOException {
		if (wide) {
			out.writeByte(org.apache.bcel.Constants.WIDE);
		}
		out.writeByte(opcode);
		if (wide) {
			out.writeShort(index);
		} else {
			out.writeByte(index);
		}
	}

	private final void setWide() {
		wide = index > org.apache.bcel.Constants.MAX_BYTE;
		if (wide) {
			length = 4; // Including the wide byte
		} else {
			length = 2;
		}
	}

	/**
	 * Read needed data (e.g. index) from file.
	 */
	@Override
	protected void initFromFile(ByteSequence bytes, boolean wide)
			throws IOException {
		this.wide = wide;
		if (wide) {
			index = bytes.readUnsignedShort();
			length = 4;
		} else {
			index = bytes.readUnsignedByte();
			length = 2;
		}
	}

	/**
	 * @return index of local variable containg the return address
	 */
	@Override
	public final int getIndex() {
		return index;
	}

	/**
	 * Set index of local variable containg the return address
	 */
	@Override
	public final void setIndex(int n) {
		if (n < 0) {
			throw new ClassGenException("Negative index value: " + n);
		}
		index = n;
		setWide();
	}

	/**
	 * @return mnemonic for instruction
	 */
	@Override
	public String toString(boolean verbose) {
		return super.toString(verbose) + " " + index;
	}

	/**
	 * @return return address type
	 */
	@Override
	public Type getType(ConstantPoolGen cp) {
		return ReturnaddressType.NO_TARGET;
	}

	/**
	 * Call corresponding visitor method(s). The order is: Call visitor methods
	 * of implemented interfaces first, then call methods according to the class
	 * hierarchy in descending order, i.e., the most specific visitXXX() call
	 * comes last.
	 * 
	 * @param v
	 *            Visitor object
	 */
	@Override
	public void accept(Visitor v) {
		v.visitRET(this);
	}
}
