Package org.eclipse.core.databinding.property.value

Source Code of org.eclipse.core.databinding.property.value.ValueProperty

/*******************************************************************************
* Copyright (c) 2008, 2010 Matthew Hall and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
*     Matthew Hall - initial API and implementation (bug 194734)
*     Matthew Hall - bug 195222
*     Ovidio Mallo - bugs 331348, 305367
******************************************************************************/

package org.eclipse.core.databinding.property.value;

import org.eclipse.core.databinding.observable.IObservable;
import org.eclipse.core.databinding.observable.Realm;
import org.eclipse.core.databinding.observable.list.IObservableList;
import org.eclipse.core.databinding.observable.map.IObservableMap;
import org.eclipse.core.databinding.observable.masterdetail.IObservableFactory;
import org.eclipse.core.databinding.observable.masterdetail.MasterDetailObservables;
import org.eclipse.core.databinding.observable.set.IObservableSet;
import org.eclipse.core.databinding.observable.value.IObservableValue;
import org.eclipse.core.databinding.property.list.IListProperty;
import org.eclipse.core.databinding.property.map.IMapProperty;
import org.eclipse.core.databinding.property.set.ISetProperty;
import org.eclipse.core.internal.databinding.property.ValuePropertyDetailList;
import org.eclipse.core.internal.databinding.property.ValuePropertyDetailMap;
import org.eclipse.core.internal.databinding.property.ValuePropertyDetailSet;
import org.eclipse.core.internal.databinding.property.ValuePropertyDetailValue;

/**
* Abstract implementation of IValueProperty
*
* @since 1.2
*/
public abstract class ValueProperty implements IValueProperty {

  /**
   * By default, this method returns <code>null</code> in case the source
   * object is itself <code>null</code>. Otherwise, this method delegates to
   * {@link #doGetValue(Object)}.
   *
   * <p>
   * Clients may override this method if they e.g. want to return a specific
   * default value in case the source object is <code>null</code>.
   * </p>
   *
   * @see #doGetValue(Object)
   *
   * @since 1.3
   */
  public Object getValue(Object source) {
    if (source == null) {
      return null;
    }
    return doGetValue(source);
  }

  /**
   * Returns the value of the property on the specified source object
   *
   * @param source
   *            the property source
   * @return the current value of the source's value property
   * @noreference This method is not intended to be referenced by clients.
   * @since 1.3
   */
  protected Object doGetValue(Object source) {
    IObservableValue observable = observe(source);
    try {
      return observable.getValue();
    } finally {
      observable.dispose();
    }
  }

  /**
   * @since 1.3
   */
  public final void setValue(Object source, Object value) {
    if (source != null) {
      doSetValue(source, value);
    }
  }

  /**
   * Sets the source's value property to the specified vlaue
   *
   * @param source
   *            the property source
   * @param value
   *            the new value
   * @since 1.3
   * @noreference This method is not intended to be referenced by clients.
   */
  protected void doSetValue(Object source, Object value) {
    IObservableValue observable = observe(source);
    try {
      observable.setValue(value);
    } finally {
      observable.dispose();
    }
  }

  public IObservableValue observe(Object source) {
    return observe(Realm.getDefault(), source);
  }

  public IObservableFactory valueFactory() {
    return new IObservableFactory() {
      public IObservable createObservable(Object target) {
        return observe(target);
      }
    };
  }

  public IObservableFactory valueFactory(final Realm realm) {
    return new IObservableFactory() {
      public IObservable createObservable(Object target) {
        return observe(realm, target);
      }
    };
  }

  public IObservableValue observeDetail(IObservableValue master) {
    return MasterDetailObservables.detailValue(master,
        valueFactory(master.getRealm()), getValueType());
  }

  /**
   * @since 1.4
   */
  public IObservableList observeDetail(IObservableList master) {
    return MasterDetailObservables.detailValues(master,
        valueFactory(master.getRealm()), getValueType());
  }

  /**
   * @since 1.4
   */
  public IObservableMap observeDetail(IObservableSet master) {
    return MasterDetailObservables.detailValues(master,
        valueFactory(master.getRealm()), getValueType());
  }

  /**
   * @since 1.4
   */
  public IObservableMap observeDetail(IObservableMap master) {
    return MasterDetailObservables.detailValues(master,
        valueFactory(master.getRealm()), getValueType());
  }

  public final IValueProperty value(IValueProperty detailValue) {
    return new ValuePropertyDetailValue(this, detailValue);
  }

  public final IListProperty list(IListProperty detailList) {
    return new ValuePropertyDetailList(this, detailList);
  }

  public final ISetProperty set(ISetProperty detailSet) {
    return new ValuePropertyDetailSet(this, detailSet);
  }

  public final IMapProperty map(IMapProperty detailMap) {
    return new ValuePropertyDetailMap(this, detailMap);
  }
}
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