package org.apache.lucene.analysis;

/**
 * Copyright 2005 The Apache Software Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/**
 * A filter that replaces accented characters in the ISO Latin 1 character set 
 * (ISO-8859-1) by their unaccented equivalent. The case will not be altered.
 * <p>
 * For instance, 'à' will be replaced by 'a'.
 * <p>
 */
public class ISOLatin1AccentFilter extends TokenFilter {
	public ISOLatin1AccentFilter(TokenStream input) {
		super(input);
	}

	public final Token next() throws java.io.IOException {
		final Token t = input.next();
		if (t == null)
			return null;
		// Return a token with filtered characters.
		return new Token(removeAccents(t.termText()), t.startOffset(), t.endOffset(), t.type());
	}

	/**
	 * To replace accented characters in a String by unaccented equivalents.
	 */
	public final static String removeAccents(String input) {
		final StringBuffer output = new StringBuffer();
		for (int i = 0; i < input.length(); i++) {
			switch (input.charAt(i)) {
				case '\u00C0' : // Ã