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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.
*
*/
package org.apache.tools.ant.filters;
import java.io.IOException;
import java.io.Reader;
import org.apache.tools.ant.types.Parameter;
/**
* Attaches a prefix to every line.
*
* Example:
* <pre><prefixlines prefix="Foo"/></pre>
*
* Or:
*
* <pre><filterreader classname="org.apache.tools.ant.filters.PrefixLines">
* <param name="prefix" value="Foo"/>
* </filterreader></pre>
*
*/
public final class PrefixLines
extends BaseParamFilterReader
implements ChainableReader {
/** Parameter name for the prefix. */
private static final String PREFIX_KEY = "prefix";
/** The prefix to be used. */
private String prefix = null;
/** Data that must be read from, if not null. */
private String queuedData = null;
/**
* Constructor for "dummy" instances.
*
* @see BaseFilterReader#BaseFilterReader()
*/
public PrefixLines() {
super();
}
/**
* Creates a new filtered reader.
*
* @param in A Reader object providing the underlying stream.
* Must not be <code>null</code>.
*/
public PrefixLines(final Reader in) {
super(in);
}
/**
* Returns the next character in the filtered stream. One line is read
* from the original input, and the prefix added. The resulting
* line is then used until it ends, at which point the next original line
* is read, etc.
*
* @return the next character in the resulting stream, or -1
* if the end of the resulting stream has been reached
*
* @exception IOException if the underlying stream throws an IOException
* during reading
*/
public int read() throws IOException {
if (!getInitialized()) {
initialize();
setInitialized(true);
}
int ch = -1;
if (queuedData != null && queuedData.length() == 0) {
queuedData = null;
}
if (queuedData != null) {
ch = queuedData.charAt(0);
queuedData = queuedData.substring(1);
if (queuedData.length() == 0) {
queuedData = null;
}
} else {
queuedData = readLine();
if (queuedData == null) {
ch = -1;
} else {
if (prefix != null) {
queuedData = prefix + queuedData;
}
return read();
}
}
return ch;
}
/**
* Sets the prefix to add at the start of each input line.
*
* @param prefix The prefix to add at the start of each input line.
* May be <code>null</code>, in which case no prefix
* is added.
*/
public void setPrefix(final String prefix) {
this.prefix = prefix;
}
/**
* Returns the prefix which will be added at the start of each input line.
*
* @return the prefix which will be added at the start of each input line
*/
private String getPrefix() {
return prefix;
}
/**
* Creates a new PrefixLines filter using the passed in
* Reader for instantiation.
*
* @param rdr A Reader object providing the underlying stream.
* Must not be <code>null</code>.
*
* @return a new filter based on this configuration, but filtering
* the specified reader
*/
public Reader chain(final Reader rdr) {
PrefixLines newFilter = new PrefixLines(rdr);
newFilter.setPrefix(getPrefix());
newFilter.setInitialized(true);
return newFilter;
}
/**
* Initializes the prefix if it is available from the parameters.
*/
private void initialize() {
Parameter[] params = getParameters();
if (params != null) {
for (int i = 0; i < params.length; i++) {
if (PREFIX_KEY.equals(params[i].getName())) {
prefix = params[i].getValue();
break;
}
}
}
}
}
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