/*
* Copyright (C) 2006 Joe Walnes.
* Copyright (C) 2006, 2007 XStream Committers.
* All rights reserved.
*
* The software in this package is published under the terms of the BSD
* style license a copy of which has been included with this distribution in
* the LICENSE.txt file.
*
* Created on 04. June 2006 by Joe Walnes
*/
package com.thoughtworks.xstream.io.binary;
import com.thoughtworks.xstream.io.StreamException;
import java.io.DataOutput;
import java.io.IOException;
import java.io.DataInput;
/**
* Represents the Tokens stored in the binary stream used by
* {@link BinaryStreamReader} and {@link BinaryStreamWriter}.
* <p/>
* <p>A token consists of a type and (depending on this type)
* it may additionally have an ID (positive long number)
* and/or a value (String).</p>
* <p/>
* <p>The first byte of the token represents how many subsequent
* bytes are used by the ID.
*
* @author Joe Walnes
* @see BinaryStreamReader
* @see BinaryStreamWriter
* @since 1.2
*/
public abstract class Token {
private static final byte TYPE_MASK = 0x7;
public static final byte TYPE_VERSION = 0x1;
public static final byte TYPE_MAP_ID_TO_VALUE = 0x2;
public static final byte TYPE_START_NODE = 0x3;
public static final byte TYPE_END_NODE = 0x4;
public static final byte TYPE_ATTRIBUTE = 0x5;
public static final byte TYPE_VALUE = 0x6;
private static final byte ID_MASK = 0x38;
private static final byte ID_ONE_BYTE = 0x08;
private static final byte ID_TWO_BYTES = 0x10;
private static final byte ID_FOUR_BYTES = 0x18;
private static final byte ID_EIGHT_BYTES = 0x20;
private final byte type;
protected long id = -1;
protected String value;
public Token(byte type) {
this.type = type;
}
public byte getType() {
return type;
}
public long getId() {
return id;
}
public String getValue() {
return value;
}
public String toString() {
return getClass().getName() + " [id=" + id + ", value='" + value + "']";
}
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
final Token token = (Token) o;
if (id != token.id) return false;
if (type != token.type) return false;
return !(value != null ? !value.equals(token.value) : token.value != null);
}
public int hashCode() {
int result;
result = type;
result = 29 * result + (int) (id ^ (id >>> 32));
result = 29 * result + (value != null ? value.hashCode() : 0);
return result;
}
public abstract void writeTo(DataOutput out, byte idType) throws IOException;
public abstract void readFrom(DataInput in, byte idType) throws IOException;
protected void writeId(DataOutput out, long id, byte idType) throws IOException {
if (id < 0) {
throw new IOException("id must not be negative " + id);
}
switch (idType) {
case ID_ONE_BYTE:
out.writeByte((byte) id + Byte.MIN_VALUE);
break;
case ID_TWO_BYTES:
out.writeShort((short) id + Short.MIN_VALUE);
break;
case ID_FOUR_BYTES:
out.writeInt((int) id + Integer.MIN_VALUE);
break;
case ID_EIGHT_BYTES:
out.writeLong(id + Long.MIN_VALUE);
break;
default:
throw new Error("Unknown idType " + idType);
}
}
protected void writeString(DataOutput out, String string) throws IOException {
out.writeUTF(string);
}
protected long readId(DataInput in, byte idType) throws IOException {
switch (idType) {
case ID_ONE_BYTE:
return in.readByte() - Byte.MIN_VALUE;
case ID_TWO_BYTES:
return in.readShort() - Short.MIN_VALUE;
case ID_FOUR_BYTES:
return in.readInt() - Integer.MIN_VALUE;
case ID_EIGHT_BYTES:
return in.readLong() - Long.MIN_VALUE;
default:
throw new Error("Unknown idType " + idType);
}
}
protected String readString(DataInput in) throws IOException {
return in.readUTF();
}
public static class Formatter {
public void write(DataOutput out, Token token) throws IOException {
long id = token.getId();
byte idType;
if (id <= Byte.MAX_VALUE - Byte.MIN_VALUE) {
idType = ID_ONE_BYTE;
} else if (id <= Short.MAX_VALUE - Short.MIN_VALUE) {
idType = ID_TWO_BYTES;
} else if (id <= (long) Integer.MAX_VALUE - (long) Integer.MIN_VALUE) { // cast to long to prevent overflo
idType = ID_FOUR_BYTES;
} else {
idType = ID_EIGHT_BYTES;
}
out.write(token.getType() + idType);
token.writeTo(out, idType);
}
public Token read(DataInput in) throws IOException {
byte nextByte = in.readByte();
byte type = (byte) (nextByte & TYPE_MASK);
byte idType = (byte) (nextByte & ID_MASK);
Token token = contructToken(type);
token.readFrom(in, idType);
return token;
}
private Token contructToken(byte type) {
switch (type) {
case Token.TYPE_START_NODE:
return new StartNode();
case Token.TYPE_MAP_ID_TO_VALUE:
return new MapIdToValue();
case Token.TYPE_ATTRIBUTE:
return new Attribute();
case Token.TYPE_END_NODE:
return new EndNode();
case Token.TYPE_VALUE:
return new Value();
default:
throw new StreamException("Unknown token type");
}
}
}
public static class MapIdToValue extends Token {
public MapIdToValue(long id, String value) {
super(TYPE_MAP_ID_TO_VALUE);
this.id = id;
this.value = value;
}
public MapIdToValue() {
super(TYPE_MAP_ID_TO_VALUE);
}
public void writeTo(DataOutput out, byte idType) throws IOException {
writeId(out, id, idType);
writeString(out, value);
}
public void readFrom(DataInput in, byte idType) throws IOException {
id = readId(in, idType);
value = readString(in);
}
}
public static class StartNode extends Token {
public StartNode(long id) {
super(TYPE_START_NODE);
this.id = id;
}
public StartNode() {
super(TYPE_START_NODE);
}
public void writeTo(DataOutput out, byte idType) throws IOException {
writeId(out, id, idType);
}
public void readFrom(DataInput in, byte idType) throws IOException {
id = readId(in, idType);
}
}
public static class EndNode extends Token {
public EndNode() {
super(TYPE_END_NODE);
}
public void writeTo(DataOutput out, byte idType) {
}
public void readFrom(DataInput in, byte idType) {
}
}
public static class Attribute extends Token {
public Attribute(long id, String value) {
super(TYPE_ATTRIBUTE);
this.id = id;
this.value = value;
}
public Attribute() {
super(TYPE_ATTRIBUTE);
}
public void writeTo(DataOutput out, byte idType) throws IOException {
writeId(out, id, idType);
writeString(out, value);
}
public void readFrom(DataInput in, byte idType) throws IOException {
this.id = readId(in, idType);
this.value = readString(in);
}
}
public static class Value extends Token {
public Value(String value) {
super(TYPE_VALUE);
this.value = value;
}
public Value() {
super(TYPE_VALUE);
}
public void writeTo(DataOutput out, byte idType) throws IOException {
writeString(out, value);
}
public void readFrom(DataInput in, byte idType) throws IOException {
value = readString(in);
}
}
}