ecommons/org.eclipse.statet.ecommons.databinding.core/src/org/eclipse/statet/ecommons/databinding/core/DataBindingSubContext.java

/*=============================================================================#
 # Copyright (c) 2012, 2021 Stephan Wahlbrink and others.
 # 
 # This program and the accompanying materials are made available under the
 # terms of the Eclipse Public License 2.0 which is available at
 # https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
 # which is available at https://www.apache.org/licenses/LICENSE-2.0.
 # 
 # SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
 # 
 # Contributors:
 #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
 #=============================================================================*/

package org.eclipse.statet.ecommons.databinding.core;

import java.util.ArrayList;

import org.eclipse.core.databinding.Binding;
import org.eclipse.core.databinding.DataBindingContext;
import org.eclipse.core.databinding.observable.IChangeListener;
import org.eclipse.core.databinding.observable.IObservable;
import org.eclipse.core.databinding.observable.ObservableTracker;
import org.eclipse.core.databinding.observable.list.IListChangeListener;
import org.eclipse.core.databinding.observable.list.ListChangeEvent;
import org.eclipse.core.databinding.observable.list.ListDiffEntry;

import org.eclipse.statet.jcommons.lang.NonNull;
import org.eclipse.statet.jcommons.lang.NonNullByDefault;
import org.eclipse.statet.jcommons.lang.Nullable;


@NonNullByDefault
public class DataBindingSubContext {
	
	
	private final DataBindingContext dbc;
	
	private final ArrayList<Binding> bindings;
	private final ArrayList<IObservable> observables;
	
	private final @Nullable IChangeListener listener;
	
	private boolean enabled= true;
	
	
	public DataBindingSubContext(final DataBindingContext dbc,
			final @Nullable IChangeListener listener) {
		this.dbc= dbc;
		this.bindings= new ArrayList<>(8);
		this.observables= new ArrayList<>(8);
		this.listener= listener;
	}
	
	public DataBindingSubContext(final DataBindingContext dbc) {
		this(dbc, null);
	}
	
	
	public DataBindingContext getDataBindingContext() {
		return this.dbc;
	}
	
	public void run(final Runnable runnable) {
		final IListChangeListener<Binding> bindingsListener= new IListChangeListener<Binding>() {
			@Override
			public void handleListChange(final ListChangeEvent<? extends Binding> event) {
				for (final ListDiffEntry<? extends Binding> diff : event.diff.getDifferences()) {
					if (diff.isAddition()) {
						addBinding(diff.getElement());
					}
					else {
						removeBinding(diff.getElement());
					}
				}
			}
		};
		
		this.dbc.getBindings().addListChangeListener(bindingsListener);
		try {
			final @NonNull IObservable[] observables= ObservableTracker.runAndCollect(runnable);
			this.observables.ensureCapacity(this.observables.size() + observables.length);
			for (int i= 0; i < observables.length; i++) {
				this.observables.add(observables[i]);
			}
		}
		finally {
			this.dbc.getBindings().removeListChangeListener(bindingsListener);
		}
	}
	
	protected void addBinding(final Binding binding) {
		this.bindings.add(binding);
		if (this.listener != null) {
			binding.getTarget().addChangeListener(this.listener);
		}
	}
	
	protected void removeBinding(final Binding binding) {
		this.bindings.add(binding);
		if (this.listener != null) {
			binding.getTarget().addChangeListener(this.listener);
		}
	}
	
	public void setEnabled(final boolean enabled) {
		if (enabled == this.enabled) {
			return;
		}
		
		this.enabled= enabled;
		
		if (this.enabled) {
			for (final Binding binding : this.bindings) {
				this.dbc.addBinding(binding);
			}
		}
		else {
			for (final Binding binding : this.bindings) {
				this.dbc.removeBinding(binding);
			}
		}
	}
	
	public void dispose() {
		for (final Binding binding : this.bindings) {
			if (!binding.isDisposed()) {
				binding.dispose();
			}
		}
		this.bindings.clear();
		
		for (final IObservable observable : this.observables) {
			if (!observable.isDisposed()) {
				observable.dispose();
			}
		}
		this.observables.clear();
	}
	
}