/*******************************************************************************
 * Copyright (c) 2000, 2004 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials 
 * are made available under the terms of the Common Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/cpl-v10.html
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.jface.text.contentassist;

import org.eclipse.jface.text.IDocument;


/**
 * Extends {@link org.eclipse.jface.text.contentassist.ICompletionProposal} 
 * with the following functions:
 * <ul>
 * 	<li>handling of trigger characters other than ENTER</li>
 * 	<li>completion proposal validation for a given offset</li>
 * 	<li>context information can be freely positioned</li>
 * </ul>
 * 
 * @since 2.0
 */
public interface ICompletionProposalExtension {
	
	/**
	 * Applies the proposed completion to the given document. The insertion
	 * has been triggered by entering the given character at the given offset.
	 * This method assumes that {@link #isValidFor(IDocument, int)} returns
	 * <code>true</code> if called for <code>offset</code>.
	 *
	 * @param document the document into which to insert the proposed completion
	 * @param trigger the trigger to apply the completion
	 * @param offset the offset at which the trigger has been activated
	 */
	void apply(IDocument document, char trigger, int offset);
	
	/**
	 * Returns whether this completion proposal is valid for the given
	 * position in the given document.
	 * 
	 * @param document the document for which the proposal is tested
	 * @param offset the offset for which the proposal is tested
	 * @return <code>true</code> iff valid
	 */
	boolean isValidFor(IDocument document, int offset);
	
	/**
	 * Returns the characters which trigger the application of this completion proposal.
	 * 
	 * @return the completion characters for this completion proposal or <code>null</code>
	 *		if no completion other than the new line character is possible
	 */
	char[] getTriggerCharacters();
	
	/**
	 * Returns the position to which the computed context information refers to or
	 * <code>-1</code> if no context information can be provided by this completion proposal.
	 * 
	 * @return the position to which the context information refers to or <code>-1</code> for no information
	 */
	int getContextInformationPosition();
}
