/jEdit/tags/after_bsh-2-0b4/org/gjt/sp/util/StandardUtilities.java

/*
 * StandardUtilities.java - Various miscallaneous utility functions
 * :tabSize=8:indentSize=8:noTabs=false:
 * :folding=explicit:collapseFolds=1:
 *
 * Copyright (C) 1999, 2006 Matthieu Casanova, Slava Pestov
 * Portions copyright (C) 2000 Richard S. Hall
 * Portions copyright (C) 2001 Dirk Moebius
 *
 * 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.util;


//{{{ Imports
import javax.swing.text.Segment;
//}}}

/**
 * Several tools that depends on JDK only.
 *
 * @author Matthieu Casanova
 * @version $Id: StandardUtilities.java 5486 2006-06-23 22:31:58Z kpouer $
 * @since 4.3pre5
 */
public class StandardUtilities
{
	
	//{{{ Text methods

	//{{{ getLeadingWhiteSpace() method
	/**
	 * Returns the number of leading white space characters in the
	 * specified string.
	 * @param str The string
	 */
	public static int getLeadingWhiteSpace(String str)
	{
		int whitespace = 0;
loop:		for(;whitespace < str.length();)
		{
			switch(str.charAt(whitespace))
			{
			case ' ': 
			case '\t':
				whitespace++;
				break;
			default:
				break loop;
			}
		}
		return whitespace;
	} //}}}

	//{{{ getTrailingWhiteSpace() method
	/**
	 * Returns the number of trailing whitespace characters in the
	 * specified string.
	 * @param str The string
	 */
	public static int getTrailingWhiteSpace(String str)
	{
		int whitespace = 0;
loop:		for(int i = str.length() - 1; i >= 0; i--)
		{
			switch(str.charAt(i))
			{
				case ' ': 
				case '\t':
					whitespace++;
					break;
				default:
					break loop;
			}
		}
		return whitespace;
	} //}}}
	
	//{{{ getLeadingWhiteSpaceWidth() method
	/**
	 * Returns the width of the leading white space in the specified
	 * string.
	 * @param str The string
	 * @param tabSize The tab size
	 */
	public static int getLeadingWhiteSpaceWidth(String str, int tabSize)
	{
		int whitespace = 0;
loop:		for(int i = 0; i < str.length(); i++)
		{
			switch(str.charAt(i))
			{
				case ' ':
					whitespace++;
					break;
				case '\t':
					whitespace += tabSize - 
						whitespace % tabSize;
					break;
				default:
					break loop;
			}
		}
		return whitespace;
	} //}}}

	//{{{ createWhiteSpace() method
	/**
	 * Creates a string of white space with the specified length.<p>
	 *
	 * To get a whitespace string tuned to the current buffer's
	 * settings, call this method as follows:
	 *
	 * <pre>myWhitespace = MiscUtilities.createWhiteSpace(myLength,
	 *     (buffer.getBooleanProperty("noTabs") ? 0
	 *     : buffer.getTabSize()));</pre>
	 *
	 * @param len The length
	 * @param tabSize The tab size, or 0 if tabs are not to be used
	 */
	public static String createWhiteSpace(int len, int tabSize)
	{
		return createWhiteSpace(len,tabSize,0);
	} //}}}

	//{{{ createWhiteSpace() method
	/**
	 * Creates a string of white space with the specified length.<p>
	 *
	 * To get a whitespace string tuned to the current buffer's
	 * settings, call this method as follows:
	 *
	 * <pre>myWhitespace = MiscUtilities.createWhiteSpace(myLength,
	 *     (buffer.getBooleanProperty("noTabs") ? 0
	 *     : buffer.getTabSize()));</pre>
	 *
	 * @param len The length
	 * @param tabSize The tab size, or 0 if tabs are not to be used
	 * @param start The start offset, for tab alignment
	 */
	public static String createWhiteSpace(int len, int tabSize, int start)
	{
		StringBuffer buf = new StringBuffer();
		if(tabSize == 0)
		{
			while(len-- > 0)
				buf.append(' ');
		}
		else if(len == 1)
			buf.append(' ');
		else
		{
			int count = (len + start % tabSize) / tabSize;
			if(count != 0)
				len += start;
			while(count-- > 0)
				buf.append('\t');
			count = len % tabSize;
			while(count-- > 0)
				buf.append(' ');
		}
		return buf.toString();
	} //}}}

	//{{{ getVirtualWidth() method
	/**
	 * Returns the virtual column number (taking tabs into account) of the
	 * specified offset in the segment.
	 *
	 * @param seg The segment
	 * @param tabSize The tab size
	 */
	public static int getVirtualWidth(Segment seg, int tabSize)
	{
		int virtualPosition = 0;

		for (int i = 0; i < seg.count; i++)
		{
			char ch = seg.array[seg.offset + i];

			if (ch == '\t')
			{
				virtualPosition += tabSize
					- virtualPosition % tabSize;
			}
			else
			{
				++virtualPosition;
			}
		}

		return virtualPosition;
	} //}}}

	//{{{ getOffsetOfVirtualColumn() method
	/**
	 * Returns the array offset of a virtual column number (taking tabs
	 * into account) in the segment.
	 *
	 * @param seg The segment
	 * @param tabSize The tab size
	 * @param column The virtual column number
	 * @param totalVirtualWidth If this array is non-null, the total
	 * virtual width will be stored in its first location if this method
	 * returns -1.
	 *
	 * @return -1 if the column is out of bounds
	 */
	public static int getOffsetOfVirtualColumn(Segment seg, int tabSize, 
					    int column, int[] totalVirtualWidth)
	{
		int virtualPosition = 0;

		for (int i = 0; i < seg.count; i++)
		{
			char ch = seg.array[seg.offset + i];

			if (ch == '\t')
			{
				int tabWidth = tabSize
					- virtualPosition % tabSize;
				if(virtualPosition >= column)
					return i;
				else
					virtualPosition += tabWidth;
			}
			else
			{
				if(virtualPosition >= column)
					return i;
				else
					++virtualPosition;
			}
		}

		if(totalVirtualWidth != null)
			totalVirtualWidth[0] = virtualPosition;
		return -1;
	} //}}}

	//}}}
	private StandardUtilities(){}
}