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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;
/**
* Converts tabs to spaces.
*
* Example:
*
* <pre><tabstospaces tablength="8"/></pre>
*
* Or:
*
* <pre><filterreader classname="org.apache.tools.ant.filters.TabsToSpaces">
* <param name="tablength" value="8"/>
* </filterreader></pre>
*
*/
public final class TabsToSpaces
extends BaseParamFilterReader
implements ChainableReader {
/** The default tab length. */
private static final int DEFAULT_TAB_LENGTH = 8;
/** Parameter name for the length of a tab. */
private static final String TAB_LENGTH_KEY = "tablength";
/** Tab length in this filter. */
private int tabLength = DEFAULT_TAB_LENGTH;
/** The number of spaces still to be read to represent the last-read tab. */
private int spacesRemaining = 0;
/**
* Constructor for "dummy" instances.
*
* @see BaseFilterReader#BaseFilterReader()
*/
public TabsToSpaces() {
super();
}
/**
* Creates a new filtered reader.
*
* @param in A Reader object providing the underlying stream.
* Must not be <code>null</code>.
*/
public TabsToSpaces(final Reader in) {
super(in);
}
/**
* Returns the next character in the filtered stream, converting tabs
* to the specified number of spaces.
*
* @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 (spacesRemaining > 0) {
spacesRemaining--;
ch = ' ';
} else {
ch = in.read();
if (ch == '\t') {
spacesRemaining = tabLength - 1;
ch = ' ';
}
}
return ch;
}
/**
* Sets the tab length.
*
* @param tabLength the number of spaces to be used when converting a tab.
*/
public void setTablength(final int tabLength) {
this.tabLength = tabLength;
}
/**
* Returns the tab length.
*
* @return the number of spaces used when converting a tab
*/
private int getTablength() {
return tabLength;
}
/**
* Creates a new TabsToSpaces 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) {
TabsToSpaces newFilter = new TabsToSpaces(rdr);
newFilter.setTablength(getTablength());
newFilter.setInitialized(true);
return newFilter;
}
/**
* Parses the parameters to set the tab length.
*/
private void initialize() {
Parameter[] params = getParameters();
if (params != null) {
for (int i = 0; i < params.length; i++) {
if (params[i] != null) {
if (TAB_LENGTH_KEY.equals(params[i].getName())) {
tabLength = Integer.parseInt(params[i].getValue());
break;
}
}
}
}
}
}
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