jaxx.compiler.binding
Class DataSource

java.lang.Object
  jaxx.compiler.binding.DataSource

public class DataSource
extends Object

Represents a Java expression which fires a PropertyChangeEvent when it can be determined that its value may have changed. Events are fired on a "best effort" basis, and events may either be fired too often (the value has not actually changed) or not often enough (the value changed but no event was fired).

Field Summary

protected String	constantId Constant id
protected static org.apache.commons.logging.Log	log Logger
protected List<JavaMethod>	methods

Constructor Summary

DataSource(String id, String constantId, String source, JAXXCompiler compiler, List<JavaMethod> methods)
Creates a new data source.

Method Summary

protected boolean	compile() Compiles the data source expression and listener.
String	getAddMemberListenerCode(DefaultObjectHandler handler, String objectCode, String memberName, String propertyChangeListenerCode, JAXXCompiler compiler) Returns a snippet of Java code which will cause a PropertyChangeListener to be notified when the member's value changes.
String	getObjectCode()
String	getRemoveMemberListenerCode(DefaultObjectHandler handler, String objectCode, String memberName, String propertyChangeListenerCode, JAXXCompiler compiler)
DataListener[]	getTrackers()
boolean	hasMethod(String methodName)
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

log

protected static final org.apache.commons.logging.Log log

Logger

constantId

protected final String constantId

Constant id

methods

protected final List<JavaMethod> methods

Constructor Detail

DataSource

public DataSource(String id,
                  String constantId,
                  String source,
                  JAXXCompiler compiler,
                  List<JavaMethod> methods)

Creates a new data source. After creating a DataSource, use compile() to cause it to function at runtime.

Parameters:

id - the DataSource's id

constantId - the DataSource constant id

source - the Java source code for the data source expression

compiler - the current JAXXCompiler

methods - where to store extra method to add to binding

Method Detail

getObjectCode

public String getObjectCode()

getTrackers

public DataListener[] getTrackers()

toString

public String toString()

Overrides:

toString in class Object

compile

protected boolean compile()
                   throws CompilerException,
                          IllegalStateException

Compiles the data source expression and listener. This method calls methods in JAXXCompiler to add the Java code that performs the data source setup. Adding listeners to DataSource is slightly more complicated than with ordinary classes, because DataSource only exists at compile time. You must pass in a Java expression which evaluates to a PropertyChangeListener; this expression will be compiled and evaluated at runtime to yield the DataSource's listener.

Returns:

true if the expression has dependencies, false otherwise

Throws:

CompilerException - if a compilation error occurs

IllegalStateException - if data source was already compiled

hasMethod

public boolean hasMethod(String methodName)

getAddMemberListenerCode

public String getAddMemberListenerCode(DefaultObjectHandler handler,
                                       String objectCode,
                                       String memberName,
                                       String propertyChangeListenerCode,
                                       JAXXCompiler compiler)

Returns a snippet of Java code which will cause a PropertyChangeListener to be notified when the member's value changes. The PropertyChangeListener is provided in the form of a Java code snippet that evaluates to a listener object.

For ordinary bound JavaBeans properties, the Java code returned is a simple call to addPropertyChangeListener. Fields and methods which do not actually fire PropertyChangeEvents when they change necessitate more complex code.

Parameters:

handler - Object handler (containts known events

objectCode - Java code which evaluates to the object to which to add the listener *@param dataBinding the name of the data binding this listener is a part of

memberName - the name of the field or method to listen to

propertyChangeListenerCode - Java code which evaluates to a PropertyChangeListener

compiler - the current JAXXCompiler

Returns:

Java code snippet which causes the listener to be added to the object

getRemoveMemberListenerCode

public String getRemoveMemberListenerCode(DefaultObjectHandler handler,
                                          String objectCode,
                                          String memberName,
                                          String propertyChangeListenerCode,
                                          JAXXCompiler compiler)