/*
 * :tabSize=4:indentSize=4:noTabs=false:
 * :folding=explicit:collapseFolds=1:
 *
 * Copyright (C) 2007 Marcelo Vanzin
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */

package org.gjt.sp.jedit.buffer;

import javax.annotation.Nonnull;

/**
 * A read-only text segment from a buffer. Allows concatenation using a
 * "linked list" approach.
 *
 * @author Marcelo Vanzin
 * @version $Id: BufferSegment.java 25698 2023-11-17 01:31:50Z vampire0 $
 * @since jEdit 4.3pre15
 */
class BufferSegment implements CharSequence
{

	public BufferSegment(char[] data,
			     int offset,
			     int len)
	{
		this(data,offset,len,null);
	}

	public BufferSegment(char[] data,
			      int offset,
			      int len,
			      BufferSegment next)
	{
		this.data = data;
		this.offset = offset;
		this.len = len;
		this.next = next;
	}

	@Override
	public char charAt(int index)
	{
		if (index < len)
			return data[offset+index];
		else if (next != null)
			return next.charAt(index-len);
		else
			throw new ArrayIndexOutOfBoundsException(index);
	}

	@Override
	public int length()
	{
		return len + ((next != null) ? next.length() : 0);
	}

	@Override
	public CharSequence subSequence(int start,
					int end)
	{
		return subSegment(start, end);
	}

	@Nonnull
	public String toString()
	{
		StringBuilder sb = new StringBuilder();
		toString(sb);
		return sb.toString();
	}

	private void toString(StringBuilder sb)
	{
		sb.append(data,offset,len);
		if (next != null)
			next.toString(sb);
	}

	private BufferSegment subSegment(int start,
					int end)
	{
		if (0 <= start && start <= end)
			if (end <= len)
				return new BufferSegment(data,offset+start,
					end-start);
			else if (next != null)
				if (start < len)
					return new BufferSegment(data,
						offset+start,len-start,
						next.subSegment(0,end-len));
				else
					return next.subSegment(start-len,
						end-len);
			else
				throw new ArrayIndexOutOfBoundsException();
		else
			throw new ArrayIndexOutOfBoundsException();
	}

	private final char[] data;
	private final int offset;
	private final int len;
	private final BufferSegment next;
}

