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	/*
	* Copyright (c) 1997, 2008, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code 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 General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/


	/*
	* The Original Code is HAT. The Initial Developer of the
	* Original Code is Bill Foote, with contributions from others
	* at JavaSoft/Sun.
	*/

	package com.sun.tools.hat.internal.model;

	import java.io.IOException;
	import com.sun.tools.hat.internal.parser.ReadBuffer;

	/*
	* Base class for lazily read Java heap objects.
	*/
	public abstract class JavaLazyReadObject extends JavaHeapObject {

	// file offset from which this object data starts
	private final long offset;

	protected JavaLazyReadObject(long offset) {
	this.offset = offset;
	}

	public final int getSize() {
	return getValueLength() + getClazz().getMinimumObjectSize();
	}

	protected final long getOffset() {
	return offset;
	}

	// return the length of the data for this object
	protected final int getValueLength() {
	try {
	return readValueLength();
	} catch (IOException exp) {
	System.err.println("lazy read failed at offset " + offset);
	exp.printStackTrace();
	return 0;
	}
	}

	// get this object's content as byte array
	protected final byte[] getValue() {
	try {
	return readValue();
	} catch (IOException exp) {
	System.err.println("lazy read failed at offset " + offset);
	exp.printStackTrace();
	return Snapshot.EMPTY_BYTE_ARRAY;
	}
	}

	// get ID of this object
	public final long getId() {
	try {
	ReadBuffer buf = getClazz().getReadBuffer();
	int idSize = getClazz().getIdentifierSize();
	if (idSize == 4) {
	return ((long)buf.getInt(offset)) & Snapshot.SMALL_ID_MASK;
	} else {
	return buf.getLong(offset);
	}
	} catch (IOException exp) {
	System.err.println("lazy read failed at offset " + offset);
	exp.printStackTrace();
	return -1;
	}
	}

	protected abstract int readValueLength() throws IOException;
	protected abstract byte[] readValue() throws IOException;

	// make Integer or Long for given object ID
	protected static Number makeId(long id) {
	if ((id & ~Snapshot.SMALL_ID_MASK) == 0) {
	return new Integer((int)id);
	} else {
	return new Long(id);
	}
	}

	// get ID as long value from Number
	protected static long getIdValue(Number num) {
	long id = num.longValue();
	if (num instanceof Integer) {
	id &= Snapshot.SMALL_ID_MASK;
	}
	return id;
	}

	// read object ID from given index from given byte array
	protected final long objectIdAt(int index, byte[] data) {
	int idSize = getClazz().getIdentifierSize();
	if (idSize == 4) {
	return ((long)intAt(index, data)) & Snapshot.SMALL_ID_MASK;
	} else {
	return longAt(index, data);
	}
	}

	// utility methods to read primitive types from byte array
	protected static byte byteAt(int index, byte[] value) {
	return value[index];
	}

	protected static boolean booleanAt(int index, byte[] value) {
	return (value[index] & 0xff) == 0? false: true;
	}

	protected static char charAt(int index, byte[] value) {
	int b1 = ((int) value[index++] & 0xff);
	int b2 = ((int) value[index++] & 0xff);
	return (char) ((b1 << 8) + b2);
	}

	protected static short shortAt(int index, byte[] value) {
	int b1 = ((int) value[index++] & 0xff);
	int b2 = ((int) value[index++] & 0xff);
	return (short) ((b1 << 8) + b2);
	}

	protected static int intAt(int index, byte[] value) {
	int b1 = ((int) value[index++] & 0xff);
	int b2 = ((int) value[index++] & 0xff);
	int b3 = ((int) value[index++] & 0xff);
	int b4 = ((int) value[index++] & 0xff);
	return ((b1 << 24) + (b2 << 16) + (b3 << 8) + b4);
	}

	protected static long longAt(int index, byte[] value) {
	long val = 0;
	for (int j = 0; j < 8; j++) {
	val = val << 8;
	int b = ((int)value[index++]) & 0xff;
	val \|= b;
	}
	return val;
	}

	protected static float floatAt(int index, byte[] value) {
	int val = intAt(index, value);
	return Float.intBitsToFloat(val);
	}

	protected static double doubleAt(int index, byte[] value) {
	long val = longAt(index, value);
	return Double.longBitsToDouble(val);
	}
	}

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