gnu.io.rfc2217.ComPortCommand Maven / Gradle / Ivy
/*
* Copyright (C) 2010 Archie L. Cobbs. All rights reserved.
*
* $Id: ComPortCommand.java 47 2011-12-07 15:56:28Z archie.cobbs $
*/
package gnu.io.rfc2217;
import java.util.Arrays;
import static gnu.io.rfc2217.RFC2217.COM_PORT_OPTION;
import static gnu.io.rfc2217.RFC2217.SERVER_OFFSET;
/**
* Superclass for RFC 2217 commands.
*
*
* Instances of this class (and all subclasses) are immutable.
*
*
* @see RFC 2217
*/
public abstract class ComPortCommand {
final String name;
final int[] bytes;
/**
* Constructor.
*
* @param name human readable name of this command
* @param command required {@code COM-PORT-OPTION} command byte value (must be the client-to-server value)
* @param bytes encoded command starting with the {@code COM-PORT-OPTION} byte
* NullPointerException if {@code bytes} is null
* IllegalArgumentException if {@code bytes} has length that is too short or too long
* IllegalArgumentException if {@code bytes[0]} is not {@link RFC2217#COM_PORT_OPTION}
* IllegalArgumentException if {@code command} is greater than or equal to {@link RFC2217#SERVER_OFFSET}
* IllegalArgumentException if {@code bytes[1]} is not {@code command}
* or {@code command} + {@link RFC2217#SERVER_OFFSET}
*/
protected ComPortCommand(String name, int command, int[] bytes) {
this.name = name;
int minLength = 2 + this.getMinPayloadLength();
int maxLength = 2 + this.getMaxPayloadLength();
if (bytes.length < minLength || bytes.length > maxLength) {
throw new IllegalArgumentException("command " + command + " length = "
+ bytes.length + " is not in the range " + minLength + ".." + maxLength);
}
this.bytes = bytes.clone(); // maintain immutability
if (this.bytes[0] != COM_PORT_OPTION)
throw new IllegalArgumentException("not a COM-PORT-OPTION");
if (command >= SERVER_OFFSET)
throw new IllegalArgumentException("invalid command " + command);
if (this.getCommand() != command && this.getCommand() != command + SERVER_OFFSET)
throw new IllegalArgumentException("not a " + name + " option");
}
/**
* Determine if this command is client-to-server or server-to-client.
*
* @return true if this command is sent from the server to the client, false for the opposite
*/
public final boolean isServerCommand() {
return this.getCommand() >= SERVER_OFFSET;
}
/**
* Get the encoding of this instance.
*
* @return encoding starting with {@code COM-PORT-OPTION}
*/
public final int[] getBytes() {
return this.bytes.clone(); // maintain immutability
}
/**
* Get the command byte.
*
* @return RFC 2217-defined byte value for this command
*/
public final int getCommand() {
return this.bytes[1] & 0xff;
}
/**
* Get the human-readable name of this option.
*/
public String getName() {
return this.name + (this.isServerCommand() ? "[S]" : "[C]");
}
/**
* Get the human-readable description of this option.
*/
@Override
public abstract String toString();
/**
* Apply visitor pattern.
*
* @param sw visitor switch handler
*/
public abstract void visit(ComPortCommandSwitch sw);
/**
* Get the option payload as bytes.
*/
byte[] getPayload() {
byte[] buf = new byte[this.bytes.length - 2];
for (int i = 2; i < bytes.length; i++)
buf[i - 2] = (byte)this.bytes[i];
return buf;
}
/**
* Get minimum required length of the payload of this command.
*/
abstract int getMinPayloadLength();
/**
* Get maximum required length of the payload of this command.
*/
abstract int getMaxPayloadLength();
@Override
public boolean equals(Object obj) {
if (obj == null || obj.getClass() != getClass())
return false;
ComPortCommand that = (ComPortCommand)obj;
return Arrays.equals(this.bytes, that.bytes);
}
@Override
public int hashCode() {
int hash = 0;
for (int i = 0; i < this.bytes.length; i++)
hash = hash * 37 + this.bytes[i];
return hash;
}
}