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.FilterReader; 020import java.io.IOException; 021import java.io.Reader; 022 023/** 024 * A filter reader that filters out characters where subclasses decide which characters to filter out. 025 */ 026public abstract class AbstractCharacterFilterReader extends FilterReader { 027 028 /** 029 * Constructs a new reader. 030 * 031 * @param reader 032 * the reader to filter 033 */ 034 protected AbstractCharacterFilterReader(final Reader reader) { 035 super(reader); 036 } 037 038 @Override 039 public int read() throws IOException { 040 int ch; 041 do { 042 ch = in.read(); 043 } while (filter(ch)); 044 return ch; 045 } 046 047 /** 048 * Returns true if the given character should be filtered out, false to keep the character. 049 * 050 * @param ch 051 * the character to test. 052 * @return true if the given character should be filtered out, false to keep the character. 053 */ 054 protected abstract boolean filter(int ch); 055 056 @Override 057 public int read(final char[] cbuf, final int off, final int len) throws IOException { 058 final int read = super.read(cbuf, off, len); 059 if (read == -1) { 060 return -1; 061 } 062 int pos = off - 1; 063 for (int readPos = off; readPos < off + read; readPos++) { 064 if (filter(read)) { 065 continue; 066 } 067 pos++; 068 if (pos < readPos) { 069 cbuf[pos] = cbuf[readPos]; 070 } 071 } 072 return pos - off + 1; 073 } 074}