com.sun.javafx.binding.ExpressionHelper Maven / Gradle / Ivy
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package com.sun.javafx.binding;
import javafx.beans.InvalidationListener;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import java.util.Arrays;
/**
* A convenience class for creating implementations of {@link javafx.beans.value.ObservableValue}.
* It contains all of the infrastructure support for value invalidation- and
* change event notification.
*
* This implementation can handle adding and removing listeners while the
* observers are being notified, but it is not thread-safe.
*
* This class keeps track of the latest value it has seen to determine if change
* listeners should be called when next {@link #fireValueChangedEvent()} is called.
* So while this value is usually the current value of the involved observable,
* it becomes the "old" value as soon as the observable is changed, until such time
* it is updated again (by calling {@link #fireValueChangedEvent()}).
*
* During this brief period, listeners may be added or removed causing the ExpressionHelper
* to perhaps switch to a different variant of itself. These different variants must be
* made aware of the currently stored latest value, as obtaining this value from the
* {@link ObservableValue} would (during that brief period) be a different value. Using
* the incorrect latest value would result in change listeners not being fired as they
* perform an equality check.
*/
public abstract class ExpressionHelper extends ExpressionHelperBase {
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Static methods
public static ExpressionHelper addListener(ExpressionHelper helper, ObservableValue observable, InvalidationListener listener) {
if ((observable == null) || (listener == null)) {
throw new NullPointerException();
}
observable.getValue(); // validate observable
return (helper == null)? new SingleInvalidation<>(observable, listener) : helper.addListener(listener);
}
public static ExpressionHelper removeListener(ExpressionHelper helper, InvalidationListener listener) {
if (listener == null) {
throw new NullPointerException();
}
return (helper == null)? null : helper.removeListener(listener);
}
public static ExpressionHelper addListener(ExpressionHelper helper, ObservableValue observable, ChangeListener listener) {
if ((observable == null) || (listener == null)) {
throw new NullPointerException();
}
return (helper == null)? new SingleChange<>(observable, observable.getValue(), listener) : helper.addListener(listener);
}
public static ExpressionHelper removeListener(ExpressionHelper helper, ChangeListener listener) {
if (listener == null) {
throw new NullPointerException();
}
return (helper == null)? null : helper.removeListener(listener);
}
public static void fireValueChangedEvent(ExpressionHelper helper) {
if (helper != null) {
helper.fireValueChangedEvent();
}
}
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Common implementations
protected final ObservableValue observable;
private ExpressionHelper(ObservableValue observable) {
this.observable = observable;
}
protected abstract ExpressionHelper addListener(InvalidationListener listener);
protected abstract ExpressionHelper removeListener(InvalidationListener listener);
protected abstract ExpressionHelper addListener(ChangeListener listener);
protected abstract ExpressionHelper removeListener(ChangeListener listener);
protected abstract void fireValueChangedEvent();
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Implementations
private static class SingleInvalidation extends ExpressionHelper {
private final InvalidationListener listener;
private SingleInvalidation(ObservableValue expression, InvalidationListener listener) {
super(expression);
this.listener = listener;
}
@Override
protected ExpressionHelper addListener(InvalidationListener listener) {
return new Generic<>(observable, this.listener, listener);
}
@Override
protected ExpressionHelper removeListener(InvalidationListener listener) {
return (listener.equals(this.listener))? null : this;
}
@Override
protected ExpressionHelper addListener(ChangeListener listener) {
return new Generic<>(observable, observable.getValue(), this.listener, listener);
}
@Override
protected ExpressionHelper removeListener(ChangeListener listener) {
return this;
}
@Override
protected void fireValueChangedEvent() {
try {
listener.invalidated(observable);
} catch (Exception e) {
Thread.currentThread().getUncaughtExceptionHandler().uncaughtException(Thread.currentThread(), e);
}
}
}
private static class SingleChange extends ExpressionHelper {
private final ChangeListener listener;
private T currentValue;
private SingleChange(ObservableValue observable, T currentValue, ChangeListener listener) {
super(observable);
this.listener = listener;
this.currentValue = currentValue;
}
@Override
protected ExpressionHelper addListener(InvalidationListener listener) {
return new Generic<>(observable, currentValue, listener, this.listener);
}
@Override
protected ExpressionHelper removeListener(InvalidationListener listener) {
return this;
}
@Override
protected ExpressionHelper addListener(ChangeListener listener) {
return new Generic<>(observable, currentValue, this.listener, listener);
}
@Override
protected ExpressionHelper removeListener(ChangeListener listener) {
return (listener.equals(this.listener))? null : this;
}
@Override
protected void fireValueChangedEvent() {
final T oldValue = currentValue;
currentValue = observable.getValue();
final boolean changed = (currentValue == null)? (oldValue != null) : !currentValue.equals(oldValue);
if (changed) {
try {
listener.changed(observable, oldValue, currentValue);
} catch (Exception e) {
Thread.currentThread().getUncaughtExceptionHandler().uncaughtException(Thread.currentThread(), e);
}
}
}
}
private static class Generic extends ExpressionHelper {
private InvalidationListener[] invalidationListeners;
private ChangeListener[] changeListeners;
private int invalidationSize;
private int changeSize;
private boolean locked;
private T currentValue;
private Generic(ObservableValue observable, InvalidationListener listener0, InvalidationListener listener1) {
super(observable);
this.invalidationListeners = new InvalidationListener[] {listener0, listener1};
this.invalidationSize = 2;
}
private Generic(ObservableValue observable, T currentValue, ChangeListener listener0, ChangeListener listener1) {
super(observable);
this.changeListeners = new ChangeListener[] {listener0, listener1};
this.changeSize = 2;
this.currentValue = currentValue;
}
private Generic(ObservableValue observable, T currentValue, InvalidationListener invalidationListener, ChangeListener changeListener) {
super(observable);
this.invalidationListeners = new InvalidationListener[] {invalidationListener};
this.invalidationSize = 1;
this.changeListeners = new ChangeListener[] {changeListener};
this.changeSize = 1;
this.currentValue = currentValue;
}
@Override
protected Generic addListener(InvalidationListener listener) {
if (invalidationListeners == null) {
invalidationListeners = new InvalidationListener[] {listener};
invalidationSize = 1;
} else {
final int oldCapacity = invalidationListeners.length;
if (locked) {
final int newCapacity = (invalidationSize < oldCapacity)? oldCapacity : (oldCapacity * 3)/2 + 1;
invalidationListeners = Arrays.copyOf(invalidationListeners, newCapacity);
} else if (invalidationSize == oldCapacity) {
invalidationSize = trim(invalidationSize, invalidationListeners);
if (invalidationSize == oldCapacity) {
final int newCapacity = (oldCapacity * 3)/2 + 1;
invalidationListeners = Arrays.copyOf(invalidationListeners, newCapacity);
}
}
invalidationListeners[invalidationSize++] = listener;
}
return this;
}
@Override
protected ExpressionHelper removeListener(InvalidationListener listener) {
if (invalidationListeners != null) {
for (int index = 0; index < invalidationSize; index++) {
if (listener.equals(invalidationListeners[index])) {
if (invalidationSize == 1) {
if (changeSize == 1) {
return new SingleChange<>(observable, currentValue, changeListeners[0]);
}
invalidationListeners = null;
invalidationSize = 0;
} else if ((invalidationSize == 2) && (changeSize == 0)) {
return new SingleInvalidation<>(observable, invalidationListeners[1-index]);
} else {
final int numMoved = invalidationSize - index - 1;
final InvalidationListener[] oldListeners = invalidationListeners;
if (locked) {
invalidationListeners = new InvalidationListener[invalidationListeners.length];
System.arraycopy(oldListeners, 0, invalidationListeners, 0, index);
}
if (numMoved > 0) {
System.arraycopy(oldListeners, index+1, invalidationListeners, index, numMoved);
}
invalidationSize--;
if (!locked) {
invalidationListeners[invalidationSize] = null; // Let gc do its work
}
}
break;
}
}
}
return this;
}
@Override
protected ExpressionHelper addListener(ChangeListener listener) {
if (changeListeners == null) {
changeListeners = new ChangeListener[] {listener};
changeSize = 1;
} else {
final int oldCapacity = changeListeners.length;
if (locked) {
final int newCapacity = (changeSize < oldCapacity)? oldCapacity : (oldCapacity * 3)/2 + 1;
changeListeners = Arrays.copyOf(changeListeners, newCapacity);
} else if (changeSize == oldCapacity) {
changeSize = trim(changeSize, changeListeners);
if (changeSize == oldCapacity) {
final int newCapacity = (oldCapacity * 3)/2 + 1;
changeListeners = Arrays.copyOf(changeListeners, newCapacity);
}
}
changeListeners[changeSize++] = listener;
}
if (changeSize == 1) {
currentValue = observable.getValue();
}
return this;
}
@Override
protected ExpressionHelper removeListener(ChangeListener listener) {
if (changeListeners != null) {
for (int index = 0; index < changeSize; index++) {
if (listener.equals(changeListeners[index])) {
if (changeSize == 1) {
if (invalidationSize == 1) {
return new SingleInvalidation<>(observable, invalidationListeners[0]);
}
changeListeners = null;
changeSize = 0;
currentValue = null; // clear current value to avoid stale reference
} else if ((changeSize == 2) && (invalidationSize == 0)) {
return new SingleChange<>(observable, currentValue, changeListeners[1-index]);
} else {
final int numMoved = changeSize - index - 1;
final ChangeListener[] oldListeners = changeListeners;
if (locked) {
changeListeners = new ChangeListener[changeListeners.length];
System.arraycopy(oldListeners, 0, changeListeners, 0, index);
}
if (numMoved > 0) {
System.arraycopy(oldListeners, index+1, changeListeners, index, numMoved);
}
changeSize--;
if (!locked) {
changeListeners[changeSize] = null; // Let gc do its work
}
}
break;
}
}
}
return this;
}
@Override
protected void fireValueChangedEvent() {
final InvalidationListener[] curInvalidationList = invalidationListeners;
final int curInvalidationSize = invalidationSize;
final ChangeListener[] curChangeList = changeListeners;
final int curChangeSize = changeSize;
try {
locked = true;
final T oldValue = currentValue;
if (curChangeSize > 0) {
/*
* Because invalidation listeners may get removed during notification, this may
* change the Helper type from Generic to SingleChange. When this transition
* occurs, it is essential the correct current value is passed to the new
* SingleChange instance. This is why the currentValue is already obtained
* before notifying the invalidation listeners.
*/
currentValue = observable.getValue();
}
for (int i = 0; i < curInvalidationSize; i++) {
try {
curInvalidationList[i].invalidated(observable);
} catch (Exception e) {
Thread.currentThread().getUncaughtExceptionHandler().uncaughtException(Thread.currentThread(), e);
}
}
if (curChangeSize > 0) {
final boolean changed = (currentValue == null)? (oldValue != null) : !currentValue.equals(oldValue);
if (changed) {
for (int i = 0; i < curChangeSize; i++) {
try {
curChangeList[i].changed(observable, oldValue, currentValue);
} catch (Exception e) {
Thread.currentThread().getUncaughtExceptionHandler().uncaughtException(Thread.currentThread(), e);
}
}
}
}
} finally {
locked = false;
}
}
}
}