org.eclipse.text/src/org/eclipse/jface/text/ILineTracker.java

/*******************************************************************************
 * Copyright (c) 2000, 2003 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;


/**
 * A line tracker maps character positions to line numbers and vice versa.
 * Initially the line tracker is informed about its underlying text
 * in order to initialize the mapping information. After that, the line 
 * tracker is informed about all changes of the underlying text allowing 
 * for incremental updates of the mapping information. It is the client's
 * responsibility to actively inform the line tacker about text changes.
 * For example, when using a line tracker in combination with a document
 * the document controls the line tracker.<p>
 * Clients may implement this interface or use the standard implementation
 * <code>DefaultLineTracker</code>.
 */
public interface ILineTracker {
		
	/**
	 * Returns the strings this tracker considers as legal line delimiters.
	 *
	 * @return the legal line delimiters
	 */
	String[] getLegalLineDelimiters();
			
	/**
	 * Returns the line delimiter of the specified line. Returns <code>null</code> if the
	 * line is not closed with a line delimiter.
	 *
	 * @param line the line whose line delimiter is queried
	 * @return the line's delimiter or <code>null</code> if line does not have a delimiter
	 * @exception BadLocationException if the line number is invalid in this tracker's line structure
	 */
	String getLineDelimiter(int line) throws BadLocationException;
	
	/**
	 * Computes the number of lines in the given text.
	 * 
	 * @param text the text whose number of lines should be computed
	 * @return the number of lines in the given text
	 */
	int computeNumberOfLines(String text);
	
	/**
	 * Returns the number of lines.
	 *
	 * @return the number of lines in this tracker's line structure
	 */
	int getNumberOfLines();
	
	/**
	 * Returns the number of lines which are occupied by a given text range.
	 *
	 * @param offset the offset of the specified text range
	 * @param length the length of the specified text range
	 * @return the number of lines occupied by the specified range
	 * @exception BadLocationException if specified range is unknown to this tracker
	 */
	int getNumberOfLines(int offset, int length) throws BadLocationException;
	
	/**
	 * Returns the position of the first character of the specified line.
	 *
	 * @param line the line of interest
	 * @return offset of the first character of the line
	 * @exception BadLocationException if the line is unknown to this tracker
	 */
	int getLineOffset(int line) throws BadLocationException;
	
	/**
	 * Returns length of the specified line including the line's delimiter.
	 *
	 * @param line the line of interest
	 * @return the length of the line
	 * @exception BadLocationException if line is unknown to this tracker
	 */
	int getLineLength(int line) throws BadLocationException;
	
	/**
	 * Returns the line number the character at the given offset belongs to.
	 *
	 * @param offset the offset whose line number to be determined
	 * @return the number of the line the offset is on
	 * @exception BadLocationException if the offset is invalid in this tracker
	 */
	int getLineNumberOfOffset(int offset) throws BadLocationException;
	
	/**
	 * Returns a line description of the line at the given offset.
	 * The description contains the start offset and the length of the line
	 * excluding the line's delimiter.
	 *
	 * @param offset the offset whose line should be described
	 * @return a region describing the line
	 * @exception BadLocationException if offset is invalid in this tracker
	 */
	IRegion getLineInformationOfOffset(int offset) throws BadLocationException;
	
	/**
	 * Returns a line description of the given line. The description
	 * contains the start offset and the length of the line excluding the line's
	 * delimiter.
	 *
	 * @param line the line that should be described
	 * @return a region describing the line
	 * @exception BadLocationException if line is unknown to this tracker
	 */
	IRegion getLineInformation(int line) throws BadLocationException;
		
	/**
	 * Informs the line tracker about the specified change in the tracked text.
	 *
	 * @param offset the offset of the replaced text
	 * @param length the length of the replaced text
	 * @param text the substitution text
	 * @exception BadLocationException if specified range is unknown to this tracker
	 */
	void replace(int offset, int length, String text) throws BadLocationException;
	
	/**
	 * Sets the tracked text to the specified text.
	 *
	 * @param text the new tracked text
	 */
	void set(String text);
}