org.apache.activemq.artemis.shaded.io.netty.buffer.search.BitapSearchProcessorFactory Maven / Gradle / Ivy
/*
* 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 org.apache.activemq.artemis.shaded.io.netty.buffer.search;
import org.apache.activemq.artemis.shaded.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 org.apache.activemq.artemis.shaded.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);
}
}