TriggerBasedMetadataProvider.java

package org.springframework.roo.classpath;

import org.springframework.roo.metadata.MetadataProvider;
import org.springframework.roo.model.JavaType;

/**
 * A {@link MetadataProvider} that produces metadata when any of various trigger
 * annotations are present on a user project type (known as the governor).
 * 
 * @author Andrew Swan
 * @since 1.2.0
 */
public interface TriggerBasedMetadataProvider extends MetadataProvider {

  /**
   * Causes this provider to generate metadata if the given annotation is
   * present.
   * 
   * @param trigger the trigger to register (can be <code>null</code>)
   */
  void addMetadataTrigger(JavaType trigger);

  /**
   * Stops this provider generating metadata if the given annotation is
   * present.
   * 
   * @param trigger the trigger to deregister (can be <code>null</code>)
   */
  void removeMetadataTrigger(JavaType trigger);
}