http://www.eclipse.org/platform: Text (Eclipse Foundation) 
Copyright (c) 2000, 2019 IBM Corporation and others.
This program and the accompanying materials
are made available under the terms of the Eclipse Public License 2.0
which accompanies this distribution, and is available at
https://www.eclipse.org/legal/epl-2.0/
SPDX-License-Identifier: EPL-2.0
Contributors:
    IBM Corporation - initial API and implementation

/*******************************************************************************
 * Copyright (c) 2000, 2019 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.jface.text;

import java.util.ArrayList;
import java.util.List;

import org.eclipse.jface.text.AbstractLineTracker.DelimiterInfo;


Abstract, read-only implementation of ILineTracker. It lets the definition of
line delimiters to subclasses. Assuming that '\n' is the only line delimiter, this abstract
implementation defines the following line scheme:

    

  •  "" -> [0,0]

  •  "a" -> [0,1]

  •  "\n" -> [0,1], [1,0]

  •  "a\n" -> [0,2], [2,0]

  •  "a\nb" -> [0,2], [2,1]

  •  "a\nbc\n" -> [0,2], [2,3], [5,0]


This class must be subclassed.

Since:3.2
/**
 * Abstract, read-only implementation of <code>ILineTracker</code>. It lets the definition of
 * line delimiters to subclasses. Assuming that '\n' is the only line delimiter, this abstract
 * implementation defines the following line scheme:
 * <ul>
 * <li> "" -&gt; [0,0]
 * <li> "a" -&gt; [0,1]
 * <li> "\n" -&gt; [0,1], [1,0]
 * <li> "a\n" -&gt; [0,2], [2,0]
 * <li> "a\nb" -&gt; [0,2], [2,1]
 * <li> "a\nbc\n" -&gt; [0,2], [2,3], [5,0]
 * </ul>
 * This class must be subclassed.
 *
 * @since 3.2
 */
abstract class ListLineTracker implements ILineTracker {

	
The line information 
/** The line information */
	private final List<Line> fLines= new ArrayList<>();
	
The length of the tracked text 
/** The length of the tracked text */
	private int fTextLength;

	
Creates a new line tracker.

/**
	 * Creates a new line tracker.
	 */
	protected ListLineTracker() {
	}

	
Binary search for the line at a given offset.

Params:
  • offset – the offset whose line should be found
Returns:the line of the offset
/**
	 * Binary search for the line at a given offset.
	 *
	 * @param offset the offset whose line should be found
	 * @return the line of the offset
	 */
	private int findLine(int offset) {

		if (fLines.isEmpty())
			return -1;

		int left= 0;
		int right= fLines.size() - 1;
		int mid= 0;
		Line line= null;

		while (left < right) {

			mid= (left + right) / 2;

			line= fLines.get(mid);
			if (offset < line.offset) {
				if (left == mid)
					right= left;
				else
					right= mid - 1;
			} else if (offset > line.offset) {
				if (right == mid)
					left= right;
				else
					left= mid + 1;
			} else if (offset == line.offset) {
				left= right= mid;
			}
		}

		line= fLines.get(left);
		if (line.offset > offset)
			--left;
		return left;
	}

	
Returns the number of lines covered by the specified text range.

Params:
  • startLine – the line where the text range starts
  • offset – the start offset of the text range
  • length – the length of the text range
Throws:
Returns:the number of lines covered by this text range
/**
	 * Returns the number of lines covered by the specified text range.
	 *
	 * @param startLine the line where the text range starts
	 * @param offset the start offset of the text range
	 * @param length the length of the text range
	 * @return the number of lines covered by this text range
	 * @exception BadLocationException if range is undefined in this tracker
	 */
	private int getNumberOfLines(int startLine, int offset, int length) throws BadLocationException {

		if (length == 0)
			return 1;

		int target= offset + length;

		Line l= fLines.get(startLine);

		if (l.delimiter == null)
			return 1;

		if (l.offset + l.length > target)
			return 1;

		if (l.offset + l.length == target)
			return 2;

		return getLineNumberOfOffset(target) - startLine + 1;
	}

	@Override
	public final int getLineLength(int line) throws BadLocationException {
		int lines= fLines.size();

		if (line < 0 || line > lines)
			throw new BadLocationException();

		if (lines == 0 || lines == line)
			return 0;

		Line l= fLines.get(line);
		return l.length;
	}

	@Override
	public final int getLineNumberOfOffset(int position) throws BadLocationException {
		if (position < 0) {
			throw new BadLocationException("Negative offset : " + position); //$NON-NLS-1$
		} else if (position > fTextLength) {
			throw new BadLocationException("Offset > length: " + position + " > " + fTextLength);  //$NON-NLS-1$//$NON-NLS-2$
		}

		if (position == fTextLength) {

			int lastLine= fLines.size() - 1;
			if (lastLine < 0)
				return 0;

			Line l= fLines.get(lastLine);
			return (l.delimiter != null ? lastLine + 1 : lastLine);
		}

		return findLine(position);
	}

	@Override
	public final IRegion getLineInformationOfOffset(int position) throws BadLocationException {
		if (position > fTextLength)
			throw new BadLocationException("Offset > length: " + position + " > " + fTextLength);  //$NON-NLS-1$//$NON-NLS-2$

		if (position == fTextLength) {
			int size= fLines.size();
			if (size == 0)
				return new Region(0, 0);
			Line l= fLines.get(size - 1);
			return (l.delimiter != null ? new Line(fTextLength, 0) : new Line(fTextLength - l.length, l.length));
		}

		return getLineInformation(findLine(position));
	}

	@Override
	public final IRegion getLineInformation(int line) throws BadLocationException {
		int lines= fLines.size();

		if (line < 0 || line > lines)
			throw new BadLocationException();

		if (lines == 0)
			return new Line(0, 0);

		if (line == lines) {
			Line l= fLines.get(line - 1);
			return new Line(l.offset + l.length, 0);
		}

		Line l= fLines.get(line);
		return (l.delimiter != null ? new Line(l.offset, l.length - l.delimiter.length()) : l);
	}

	@Override
	public final int getLineOffset(int line) throws BadLocationException {
		int lines= fLines.size();

		if (line < 0 || line > lines)
			throw new BadLocationException();

		if (lines == 0)
			return 0;

		if (line == lines) {
			Line l= fLines.get(line - 1);
			if (l.delimiter != null)
				return l.offset + l.length;
			throw new BadLocationException();
		}

		Line l= fLines.get(line);
		return l.offset;
	}

	@Override
	public final int getNumberOfLines() {
		int lines= fLines.size();

		if (lines == 0)
			return 1;

		Line l= fLines.get(lines - 1);
		return (l.delimiter != null ? lines + 1 : lines);
	}

	@Override
	public final int getNumberOfLines(int position, int length) throws BadLocationException {

		if (position < 0 || position + length > fTextLength)
			throw new BadLocationException();

		if (length == 0) // optimization
			return 1;

		return getNumberOfLines(getLineNumberOfOffset(position), position, length);
	}

	@Override
	public final int computeNumberOfLines(String text) {
		int count= 0;
		int start= 0;
		DelimiterInfo delimiterInfo= nextDelimiterInfo(text, start);
		while (delimiterInfo != null && delimiterInfo.delimiterIndex > -1) {
			++count;
			start= delimiterInfo.delimiterIndex + delimiterInfo.delimiterLength;
			delimiterInfo= nextDelimiterInfo(text, start);
		}
		return count;
	}

	@Override
	public final String getLineDelimiter(int line) throws BadLocationException {
		int lines= fLines.size();

		if (line < 0 || line > lines)
			throw new BadLocationException();

		if (lines == 0)
			return null;

		if (line == lines)
			return null;

		Line l= fLines.get(line);
		return l.delimiter;
	}

	
Returns the information about the first delimiter found in the given text starting at the
given offset.

Params:
  • text – the text to be searched
  • offset – the offset in the given text
Returns:the information of the first found delimiter or null
/**
	 * Returns the information about the first delimiter found in the given text starting at the
	 * given offset.
	 *
	 * @param text the text to be searched
	 * @param offset the offset in the given text
	 * @return the information of the first found delimiter or <code>null</code>
	 */
	protected abstract DelimiterInfo nextDelimiterInfo(String text, int offset);

	
Creates the line structure for the given text. Newly created lines are inserted into the line
structure starting at the given position. Returns the number of newly created lines.

Params:
  • text – the text for which to create a line structure
  • insertPosition – the position at which the newly created lines are inserted into the
       tracker's line structure
  • offset – the offset of all newly created lines
Returns:the number of newly created lines
/**
	 * Creates the line structure for the given text. Newly created lines are inserted into the line
	 * structure starting at the given position. Returns the number of newly created lines.
	 *
	 * @param text the text for which to create a line structure
	 * @param insertPosition the position at which the newly created lines are inserted into the
	 *        tracker's line structure
	 * @param offset the offset of all newly created lines
	 * @return the number of newly created lines
	 */
	private int createLines(String text, int insertPosition, int offset) {

		int count= 0;
		int start= 0;
		DelimiterInfo delimiterInfo= nextDelimiterInfo(text, 0);

		while (delimiterInfo != null && delimiterInfo.delimiterIndex > -1) {

			int index= delimiterInfo.delimiterIndex + (delimiterInfo.delimiterLength - 1);

			if (insertPosition + count >= fLines.size())
				fLines.add(new Line(offset + start, offset + index, delimiterInfo.delimiter));
			else
				fLines.add(insertPosition + count, new Line(offset + start, offset + index, delimiterInfo.delimiter));

			++count;
			start= index + 1;
			delimiterInfo= nextDelimiterInfo(text, start);
		}

		if (start < text.length()) {
			if (insertPosition + count < fLines.size()) {
				// there is a line below the current
				Line l= fLines.get(insertPosition + count);
				int delta= text.length() - start;
				l.offset-= delta;
				l.length+= delta;
			} else {
				fLines.add(new Line(offset + start, offset + text.length() - 1, null));
				++count;
			}
		}

		return count;
	}

	@Override
	public final void replace(int position, int length, String text) throws BadLocationException {
		throw new UnsupportedOperationException();
	}

	@Override
	public final void set(String text) {
		fLines.clear();
		if (text != null) {
			fTextLength= text.length();
			createLines(text, 0, 0);
		} else {
			fTextLength= 0;
		}
	}

	
Returns the internal data structure, a List of Lines. Used only by TreeLineTracker(ListLineTracker). 
Returns:the internal list of lines.
/**
	 * Returns the internal data structure, a {@link List} of {@link Line}s. Used only by
	 * {@link TreeLineTracker#TreeLineTracker(ListLineTracker)}.
	 *
	 * @return the internal list of lines.
	 */
	final List<Line> getLines() {
		return fLines;
	}
}