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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.jasper.compiler;
import java.io.PrintWriter;
/**
* This class filters duplicate newlines instructions from the compiler output, and therefore from the runtime JSP. The
* duplicates typically happen because the compiler has multiple branches that write them, but they operate
* independently and don't realize that the previous output was identical. Removing these lines makes the JSP more
* efficient by executing fewer operations during runtime.
*/
public class NewlineReductionServletWriter extends ServletWriter {
private static final String NEWLINE_WRITE_TEXT = "out.write('\\n');";
private boolean lastWriteWasNewline;
public NewlineReductionServletWriter(PrintWriter writer) {
super(writer);
}
@Override
public void printil(String s) {
if (s.equals(NEWLINE_WRITE_TEXT)) {
if (lastWriteWasNewline) {
// do nothing
return;
} else {
lastWriteWasNewline = true;
}
} else {
lastWriteWasNewline = false;
}
super.printil(s);
}
}
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