    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017package org.apache.commons.io.input;
    018
    019import java.io.Reader;
    020import java.util.Collections;
    021import java.util.Set;
    022
    023/**
    024 * A filter reader that removes a given set of characters represented as <code>int</code> code points, handy to remove
    025 * known junk characters from CSV files for example.
    026 * <p>
    027 * This class must convert each <code>int</code> read to an <code>Integer</code>. You can increase the Integer cache
    028 * with a system property, see {@link Integer}.
    029 * </p>
    030 */
    031public class CharacterSetFilterReader extends AbstractCharacterFilterReader {
    032
    033    private static final Set<Integer> EMPTY_SET = Collections.emptySet();
    034    private final Set<Integer> skipSet;
    035
    036    /**
    037     * Constructs a new reader.
    038     *
    039     * @param reader
    040     *            the reader to filter.
    041     * @param skip
    042     *            the set of characters to filter out.
    043     */
    044    public CharacterSetFilterReader(final Reader reader, final Set<Integer> skip) {
    045        super(reader);
    046        this.skipSet = skip == null ? EMPTY_SET : Collections.unmodifiableSet(skip);
    047    }
    048
    049    @Override
    050    protected boolean filter(final int ch) {
    051        // Note WRT Integer.valueOf(): You can increase the Integer cache with a system property, see {@link Integer}.
    052        return skipSet.contains(Integer.valueOf(ch));
    053    }
    054
    055}