/jEdit/tags/jedit-4-5-pre1/org/gjt/sp/jedit/buffer/IndentFoldHandler.java

  1/*
  2 * IndentFoldHandler.java - Indent-based fold handler
  3 * :tabSize=8:indentSize=8:noTabs=false:
  4 * :folding=explicit:collapseFolds=1:
  5 *
  6 * Copyright (C) 2001, 2002 Slava Pestov
  7 *
  8 * This program is free software; you can redistribute it and/or
  9 * modify it under the terms of the GNU General Public License
 10 * as published by the Free Software Foundation; either version 2
 11 * of the License, or any later version.
 12 *
 13 * This program is distributed in the hope that it will be useful,
 14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 16 * GNU General Public License for more details.
 17 *
 18 * You should have received a copy of the GNU General Public License
 19 * along with this program; if not, write to the Free Software
 20 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 21 */
 22
 23package org.gjt.sp.jedit.buffer;
 24
 25import java.util.ArrayList;
 26import java.util.List;
 27
 28import javax.swing.text.Segment;
 29
 30/**
 31 * A fold handler that folds lines based on their indent level.
 32 * @author Slava Pestov
 33 * @version $Id: IndentFoldHandler.java 16133 2009-08-31 21:07:15Z shlomy $
 34 * @since jEdit 4.0pre1
 35 */
 36public class IndentFoldHandler extends FoldHandler
 37{
 38	public IndentFoldHandler()
 39	{
 40		super("indent");
 41	}
 42
 43	// Returns the width of leading whitespace in the given segment
 44	// if it contains non-whitespace characters, or (-1) otherwise.
 45	private int getLeadingWhitespaceWidth(Segment seg, int tabSize)
 46	{
 47		int offset = seg.offset;
 48		int count = seg.count;
 49		int whitespace = 0;
 50
 51		for(int i = 0; i < count; i++)
 52		{
 53			switch(seg.array[offset + i])
 54			{
 55			case ' ':
 56				whitespace++;
 57				break;
 58			case '\t':
 59				whitespace += (tabSize - whitespace % tabSize);
 60				break;
 61			default:
 62				return whitespace;
 63			}
 64		}
 65		return (-1);
 66	}
 67
 68	//{{{ getFoldLevel() method
 69	/**
 70	 * Returns the fold level of the specified line. For a whitespace-only
 71	 * line, returns the fold level of the next non-whitespace line, or
 72	 * the level of the previous line if no non-whitespace line follows or if
 73	 * the level of the previous line is higher.
 74	 * @param buffer The buffer in question
 75	 * @param lineIndex The line index
 76	 * @param seg A segment the fold handler can use to obtain any
 77	 * text from the buffer, if necessary
 78	 * @return The fold level of the specified line
 79	 * @since jEdit 4.0pre1
 80	 */
 81	public int getFoldLevel(JEditBuffer buffer, int lineIndex, Segment seg)
 82	{
 83		int tabSize = buffer.getTabSize();
 84		// Look for first non-whitespace line starting at lineIndex
 85		int prevLevel = 0;
 86		for (int index = lineIndex; index < buffer.getLineCount(); index++)
 87		{
 88			buffer.getLineText(index,seg);
 89			int whitespace = getLeadingWhitespaceWidth(seg,tabSize);
 90			if(whitespace >= 0)	// Non-whitespace found on line
 91				return (whitespace > prevLevel) ? whitespace : prevLevel;
 92			if(index == 0)
 93				return 0;
 94			if(index == lineIndex)
 95				prevLevel = buffer.getFoldLevel(lineIndex - 1);
 96		}
 97		// All lines from lineIndex are whitespace-only - use fold
 98		// level of previous line.
 99		return prevLevel;
100	} //}}}
101
102	//{{{ getPrecedingFoldLevels() method
103	/**
104	 * Returns the fold levels of the lines preceding the specified line,
105	 * which depend on the specified line.
106	 * @param buffer The buffer in question
107	 * @param lineIndex The line index
108	 * @param seg A segment the fold handler can use to obtain any
109	 * @param lineFoldLevel The fold level of the specified line
110	 * @return The fold levels of the preceding lines, in decreasing line
111	 * number order (i.e. bottomost line first).
112	 * @since jEdit 4.3pre18
113	 */
114	public List<Integer> getPrecedingFoldLevels(JEditBuffer buffer,
115		int lineIndex, Segment seg, int lineFoldLevel)
116	{
117		List<Integer> precedingFoldLevels = new ArrayList<Integer>();
118		int tabSize = buffer.getTabSize();
119		int whitespace = 0;
120		int index;
121		// Find previous non-whitespace-only line
122		for (index = lineIndex - 1; index > 0; index--)
123		{
124			buffer.getLineText(index,seg);
125			whitespace = getLeadingWhitespaceWidth(seg,tabSize);
126			if (whitespace >= 0)
127				break;
128		}
129		int max = (lineFoldLevel > whitespace) ? lineFoldLevel : whitespace;
130		for (index++; index < lineIndex; index++)
131			precedingFoldLevels.add(Integer.valueOf(max));
132		return precedingFoldLevels;
133	}
134	//}}}
135
136}