content: /*******************************************************************************
   * Copyright (c) 2000, 2008 IBM Corporation 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:
   *     IBM Corporation - initial API and implementation
   *******************************************************************************/
  package org.eclipse.wst.jsdt.ui.text.java;
  
  import java.util.List;
  
  import org.eclipse.core.runtime.IProgressMonitor;
  
  /**
   * Computes completions and context information displayed by the JavaScript editor content assistant.
   * Contributions to the <tt>org.eclipse.wst.jsdt.ui.javaCompletionProposalComputer</tt> extension point
   * must implement this interface.
   * 
   *
   * Provisional API: This class/interface is part of an interim API that is still under development and expected to
   * change significantly before reaching stability. It is being made available at this early stage to solicit feedback
   * from pioneering adopters on the understanding that any code that uses this API will almost certainly be broken
   * (repeatedly) as the API evolves. */
  public interface IJavaCompletionProposalComputer {
  	/**
  	 * Informs the computer that a content assist session has started. This call will always be
  	 * followed by a {@link #sessionEnded()} call, but not necessarily by calls to
  	 * {@linkplain #computeCompletionProposals(ContentAssistInvocationContext, IProgressMonitor) computeCompletionProposals}
  	 * or
  	 * {@linkplain #computeContextInformation(ContentAssistInvocationContext, IProgressMonitor) computeContextInformation}.
  	 */
  	void sessionStarted();
  
  	/**
  	 * Returns a list of completion proposals valid at the given invocation context.
  	 * 
  	 * @param context the context of the content assist invocation
  	 * @param monitor a progress monitor to report progress. The monitor is private to this
  	 *        invocation, i.e. there is no need for the receiver to spawn a sub monitor.
  	 * @return a list of completion proposals (element type: {@link org.eclipse.jface.text.contentassist.ICompletionProposal})
  	 */
  	List computeCompletionProposals(ContentAssistInvocationContext context, IProgressMonitor monitor);
  
  	/**
  	 * Returns context information objects valid at the given invocation context.
  	 * 
  	 * @param context the context of the content assist invocation
  	 * @param monitor a progress monitor to report progress. The monitor is private to this
  	 *        invocation, i.e. there is no need for the receiver to spawn a sub monitor.
  	 * @return a list of context information objects (element type: {@link org.eclipse.jface.text.contentassist.IContextInformation})
  	 */
  	List computeContextInformation(ContentAssistInvocationContext context, IProgressMonitor monitor);
  
  	/**
  	 * Returns the reason why this computer was unable to produce any completion proposals or
  	 * context information.
  	 * 
  	 * @return an error message or <code>null</code> if no error occurred
  	 */
  	String getErrorMessage();
  
  	/**
  	 * Informs the computer that a content assist session has ended. This call will always be after
  	 * any calls to
  	 * {@linkplain #computeCompletionProposals(ContentAssistInvocationContext, IProgressMonitor) computeCompletionProposals}
  	 * and
  	 * {@linkplain #computeContextInformation(ContentAssistInvocationContext, IProgressMonitor) computeContextInformation}.
  	 */
  	void sessionEnded();
  }
  