/*
* 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 java.util.Vector;
import org.apache.tools.ant.types.Parameter;
/**
* This filter strips line comments.
*
* Example:
*
* <pre><striplinecomments>
* <comment value="#"/>
* <comment value="--"/>
* <comment value="REM "/>
* <comment value="rem "/>
* <comment value="//"/>
* </striplinecomments></pre>
*
* Or:
*
* <pre><filterreader
* classname="org.apache.tools.ant.filters.StripLineComments">
* <param type="comment" value="#"/>
* <param type="comment" value="--"/>
* <param type="comment" value="REM "/>
* <param type="comment" value="rem "/>
* <param type="comment" value="//"/>
* </filterreader></pre>
*
*/
public final class StripLineComments
extends BaseParamFilterReader
implements ChainableReader {
/** Parameter name for the comment prefix. */
private static final String COMMENTS_KEY = "comment";
/** Vector that holds the comment prefixes. */
private Vector<String> comments = new Vector<String>();
/** The line that has been read ahead. */
private String line = null;
/**
* Constructor for "dummy" instances.
*
* @see BaseFilterReader#BaseFilterReader()
*/
public StripLineComments() {
super();
}
/**
* Creates a new filtered reader.
*
* @param in A Reader object providing the underlying stream.
* Must not be <code>null</code>.
*/
public StripLineComments(final Reader in) {
super(in);
}
/**
* Returns the next character in the filtered stream, only including
* lines from the original stream which don't start with any of the
* specified comment prefixes.
*
* @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 (line != null) {
ch = line.charAt(0);
if (line.length() == 1) {
line = null;
} else {
line = line.substring(1);
}
} else {
line = readLine();
final int commentsSize = comments.size();
while (line != null) {
for (int i = 0; i < commentsSize; i++) {
String comment = comments.elementAt(i);
if (line.startsWith(comment)) {
line = null;
break;
}
}
if (line == null) {
// line started with comment
line = readLine();
} else {
break;
}
}
if (line != null) {
return read();
}
}
return ch;
}
/**
* Adds a <code>comment</code> element to the list of prefixes.
*
* @param comment The <code>comment</code> element to add to the
* list of comment prefixes to strip. Must not be <code>null</code>.
*/
public void addConfiguredComment(final Comment comment) {
comments.addElement(comment.getValue());
}
/**
* Sets the list of comment prefixes to strip.
*
* @param comments A list of strings, each of which is a prefix
* for a comment line. Must not be <code>null</code>.
*/
private void setComments(final Vector<String> comments) {
this.comments = comments;
}
/**
* Returns the list of comment prefixes to strip.
*
* @return the list of comment prefixes to strip.
*/
private Vector<String> getComments() {
return comments;
}
/**
* Creates a new StripLineComments 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) {
StripLineComments newFilter = new StripLineComments(rdr);
newFilter.setComments(getComments());
newFilter.setInitialized(true);
return newFilter;
}
/**
* Parses the parameters to set the comment prefixes.
*/
private void initialize() {
Parameter[] params = getParameters();
if (params != null) {
for (int i = 0; i < params.length; i++) {
if (COMMENTS_KEY.equals(params[i].getType())) {
comments.addElement(params[i].getValue());
}
}
}
}
/**
* The class that holds a comment representation.
*/
public static class Comment {
/** The prefix for a line comment. */
private String value;
/**
* Sets the prefix for this type of line comment.
*
* @param comment The prefix for a line comment of this type.
* Must not be <code>null</code>.
*/
public final void setValue(String comment) {
if (value != null) {
throw new IllegalStateException("Comment value already set.");
}
value = comment;
}
/**
* Returns the prefix for this type of line comment.
*
* @return the prefix for this type of line comment.
*/
public final String getValue() {
return value;
}
/**
* Alt. syntax to set the prefix for this type of line comment.
*
* @param comment The prefix for a line comment of this type.
* Must not be <code>null</code>.
*/
public void addText(String comment) {
setValue(comment);
}
}
}