io.netty.buffer.search.BitapSearchProcessorFactory Maven / Gradle / Ivy
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This artifact provides a single jar that contains all classes required to use remote EJB and JMS, including
all dependencies. It is intended for use by those not using maven, maven users should just import the EJB and
JMS BOM's instead (shaded JAR's cause lots of problems with maven, as it is very easy to inadvertently end up
with different versions on classes on the class path).
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/*
* Copyright 2020 The Netty Project
*
* The Netty Project 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:
*
* https://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 io.netty.buffer.search;
import io.netty.util.internal.PlatformDependent;
/**
* Implements Bitap string search algorithm.
* Use static {@link AbstractSearchProcessorFactory#newBitapSearchProcessorFactory}
* to create an instance of this factory.
* Use {@link BitapSearchProcessorFactory#newSearchProcessor} to get an instance of {@link io.netty.util.ByteProcessor}
* implementation for performing the actual search.
* @see AbstractSearchProcessorFactory
*/
public class BitapSearchProcessorFactory extends AbstractSearchProcessorFactory {
private final long[] bitMasks = new long[256];
private final long successBit;
public static class Processor implements SearchProcessor {
private final long[] bitMasks;
private final long successBit;
private long currentMask;
Processor(long[] bitMasks, long successBit) {
this.bitMasks = bitMasks;
this.successBit = successBit;
}
@Override
public boolean process(byte value) {
currentMask = ((currentMask << 1) | 1) & PlatformDependent.getLong(bitMasks, value & 0xffL);
return (currentMask & successBit) == 0;
}
@Override
public void reset() {
currentMask = 0;
}
}
BitapSearchProcessorFactory(byte[] needle) {
if (needle.length > 64) {
throw new IllegalArgumentException("Maximum supported search pattern length is 64, got " + needle.length);
}
long bit = 1L;
for (byte c: needle) {
bitMasks[c & 0xff] |= bit;
bit <<= 1;
}
successBit = 1L << (needle.length - 1);
}
/**
* Returns a new {@link Processor}.
*/
@Override
public Processor newSearchProcessor() {
return new Processor(bitMasks, successBit);
}
}