Module hw06

Package provided.abcMusic.musicFW

Class APhraseVisitor

java.lang.Object

provided.abcMusic.musicFW.APhraseVisitor

All Implemented Interfaces:

IPhraseVisitor

public abstract class APhraseVisitor
extends Object
implements IPhraseVisitor

Command-based implementation of IPhraseVisitor that uses IPhraseVisitorCmds stored in a hash table.

Author:

swong

Field Summary

Fields

Modifier and Type	Field	Description
private Map<String,IPhraseVisitorCmd>	cmds	The dictionary of commands, implemented using a hash table.
private IPhraseVisitorCmd	defaultCmd	The default command to use when caseAt is called with an ID that is not in the hashtable as a key.

Constructor Summary

Constructors

Constructor	Description
APhraseVisitor()	Constructor that installs a default cmd that throws an IllegalArgumentException on any unknown host.
APhraseVisitor(IPhraseVisitorCmd defaultCmd)	Constructor that sets the default cmd to the supplied cmd.

Method Summary

Modifier and Type	Method	Description
void	addCmd(String id, IPhraseVisitorCmd cmd)	Add the given command to the dictionary, associated with the given id value.
Object	caseAt(String id, IPhrase host, Object... params)	Runs the command associated with the given id, passing along the given host and vararg parameters.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

defaultCmd

private IPhraseVisitorCmd defaultCmd

The default command to use when caseAt is called with an ID that is not in the hashtable as a key.

cmds

private Map<String,IPhraseVisitorCmd> cmds

The dictionary of commands, implemented using a hash table.

Constructor Details

APhraseVisitor

public APhraseVisitor()

Constructor that installs a default cmd that throws an IllegalArgumentException on any unknown host. * ---------------------------------------------- Abstract extended visitor implementation that uses a dictionary of commands to associate commands with host IDs.

APhraseVisitor

public APhraseVisitor(IPhraseVisitorCmd defaultCmd)

Constructor that sets the default cmd to the supplied cmd.

Parameters:

defaultCmd - the default cmd to use.

Method Details

caseAt

public Object caseAt(String id,
 IPhrase host,
 Object... params)

Runs the command associated with the given id, passing along the given host and vararg parameters. If there is no cmd associated with the given id in the dictionary, then use the default cmd.

Specified by:

caseAt in interface IPhraseVisitor

Parameters:

id - The ID value that identifies the host

host - The host IPhrase object

params - vararg list of parameters that might be used. Can be called with no input params.

Returns:

the result of executing the associated cmd.

addCmd

public void addCmd(String id,
 IPhraseVisitorCmd cmd)

Add the given command to the dictionary, associated with the given id value.

Parameters:

id - The id of the host that will use this command

cmd - The command that will be run when the host calls for it.