ActivatableHandler.java

package sk.stuba.fiit.perconik.eclipse.core.commands;

import java.util.Collection;
import java.util.Map;

import org.eclipse.core.commands.AbstractHandler;
import org.eclipse.ui.handlers.IHandlerActivation;
import org.eclipse.ui.handlers.IHandlerService;

import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkState;
import static com.google.common.collect.Lists.newArrayList;
import static com.google.common.collect.Maps.newLinkedHashMap;

public abstract class ActivatableHandler extends AbstractHandler {
  private final Map<String, IHandlerActivation> activations;

  protected ActivatableHandler() {
    this.activations = newLinkedHashMap();
  }

  public final IHandlerActivation activate(final String identifier) {
    return activate(identifier, Handlers.getHandlerService());
  }

  public final IHandlerActivation activate(final String identifier, final IHandlerService service) {
    checkNotNull(service);

    synchronized (this.activations) {
      return this.activateInternal(identifier, service);
    }
  }

  private final IHandlerActivation activateInternal(final String identifier, final IHandlerService service) {
    checkState(!this.activations.containsKey(identifier));

    IHandlerActivation activation = service.activateHandler(identifier, this);

    this.activations.put(identifier, activation);

    return activation;
  }

  public final void deactivate() {
    synchronized (this.activations) {
      for (String identifier: this.activations.keySet()) {
        this.deactivateInternal(identifier);
      }
    }
  }

  public final void deactivate(final String identifier) {
    synchronized (this.activations) {
      this.deactivateInternal(identifier);
    }
  }

  private final void deactivateInternal(final String identifier) {
    IHandlerActivation activation = this.activations.get(identifier);

    checkState(identifier != null);

    IHandlerService service = activation.getHandlerService();

    if (service != null) {
      service.deactivateHandler(activation);
    }
  }

  public final Collection<IHandlerActivation> getActivations() {
    return newArrayList(this.activations.values());
  }
}