/jEdit/tags/jedit-4-0-pre5/org/gjt/sp/jedit/syntax/KeywordMap.java

/*
 * KeywordMap.java - Fast keyword->id map
 * Copyright (C) 1998, 1999 Slava Pestov
 * Copyright (C) 1999 Mike Dillon
 *
 * 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.syntax;

import javax.swing.text.Segment;
import java.util.Vector;
import org.gjt.sp.jedit.TextUtilities;

/**
 * A <code>KeywordMap</code> is similar to a hashtable in that it maps keys
 * to values. However, the `keys' are Swing segments. This allows lookups of
 * text substrings without the overhead of creating a new string object.
 *
 * @author Slava Pestov, Mike Dillon
 * @version $Id: KeywordMap.java 3931 2001-12-02 11:40:51Z spestov $
 */
public class KeywordMap
{
	/**
	 * Creates a new <code>KeywordMap</code>.
	 * @param ignoreCase True if keys are case insensitive
	 */
	public KeywordMap(boolean ignoreCase)
	{
		this(ignoreCase, 52);
		this.ignoreCase = ignoreCase;
		noWordSep = new StringBuffer();
	}

	/**
	 * Creates a new <code>KeywordMap</code>.
	 * @param ignoreCase True if the keys are case insensitive
	 * @param mapLength The number of `buckets' to create.
	 * A value of 52 will give good performance for most maps.
	 */
	public KeywordMap(boolean ignoreCase, int mapLength)
	{
		this.mapLength = mapLength;
		this.ignoreCase = ignoreCase;
		map = new Keyword[mapLength];
	}

	/**
	 * Looks up a key.
	 * @param text The text segment
	 * @param offset The offset of the substring within the text segment
	 * @param length The length of the substring
	 */
	public byte lookup(Segment text, int offset, int length)
	{
		if(length == 0)
			return Token.NULL;
		Keyword k = map[getSegmentMapKey(text, offset, length)];
		while(k != null)
		{
			if(length != k.keyword.length)
			{
				k = k.next;
				continue;
			}
			if(TextUtilities.regionMatches(ignoreCase,text,offset,
				k.keyword))
				return k.id;
			k = k.next;
		}
		return Token.NULL;
	}

	/**
	 * Adds a key-value mapping.
	 * @param keyword The key
	 * @param id The value
	 */
	public void add(String keyword, byte id)
	{
		int key = getStringMapKey(keyword);

		char[] chars = keyword.toCharArray();

		// complete-word command needs a list of all non-alphanumeric
		// characters used in a keyword map.
loop:		for(int i = 0; i < chars.length; i++)
		{
			char ch = chars[i];
			if(!Character.isLetterOrDigit(ch))
			{
				for(int j = 0; j < noWordSep.length(); j++)
				{
					if(noWordSep.charAt(j) == ch)
						continue loop;
				}

				noWordSep.append(ch);
			}
		}

		map[key] = new Keyword(chars,id,map[key]);
	}

	/**
	 * Returns all non-alphanumeric characters that appear in the
	 * keywords of this keyword map.
	 * @since jEdit 4.0pre3
	 */
	public String getNonAlphaNumericChars()
	{
		return noWordSep.toString();
	}

	/**
	 * Returns an array containing all keywords in this keyword map.
	 * @since jEdit 4.0pre3
	 */
	public String[] getKeywords()
	{
		Vector vector = new Vector(100);
		for(int i = 0; i < map.length; i++)
		{
			Keyword keyword = map[i];
			while(keyword != null)
			{
				vector.addElement(new String(keyword.keyword));
				keyword = keyword.next;
			}
		}
		String[] retVal = new String[vector.size()];
		vector.copyInto(retVal);
		return retVal;
	}

	/**
	 * Returns true if the keyword map is set to be case insensitive,
	 * false otherwise.
	 */
	public boolean getIgnoreCase()
	{
		return ignoreCase;
	}

	/**
	 * Sets if the keyword map should be case insensitive.
	 * @param ignoreCase True if the keyword map should be case
	 * insensitive, false otherwise
	 */
	public void setIgnoreCase(boolean ignoreCase)
	{
		this.ignoreCase = ignoreCase;
	}

	// protected members
	protected int mapLength;

	protected int getStringMapKey(String s)
	{
		return (Character.toUpperCase(s.charAt(0)) +
				Character.toUpperCase(s.charAt(s.length()-1)))
				% mapLength;
	}

	protected int getSegmentMapKey(Segment s, int off, int len)
	{
		return (Character.toUpperCase(s.array[off]) +
				Character.toUpperCase(s.array[off + len - 1]))
				% mapLength;
	}

	// private members
	class Keyword
	{
		public Keyword(char[] keyword, byte id, Keyword next)
		{
			this.keyword = keyword;
			this.id = id;
			this.next = next;
		}

		public char[] keyword;
		public byte id;
		public Keyword next;
	}

	private Keyword[] map;
	private boolean ignoreCase;
	private StringBuffer noWordSep;
}