/*
* 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.flink.cep.nfa;
import org.apache.flink.api.common.typeutils.TypeSerializer;
import org.apache.flink.api.common.typeutils.base.IntSerializer;
import org.apache.flink.api.common.typeutils.base.TypeSerializerSingleton;
import org.apache.flink.core.memory.DataInputView;
import org.apache.flink.core.memory.DataOutputView;
import java.io.IOException;
import java.io.Serializable;
import java.util.Arrays;
/**
* Versioning scheme which allows to retrieve dependencies between different versions.
*
* A dewey number consists of a sequence of digits d1.d2.d3. ... .dn. A dewey number v is compatible
* to v' iff v contains v' as a prefix or if both dewey number differ only in the last digit and
* the last digit of v is greater than v'.
*
*/
public class DeweyNumber implements Serializable {
private static final long serialVersionUID = 6170434818252267825L;
// sequence of digits
private final int[] deweyNumber;
public DeweyNumber(int start) {
deweyNumber = new int[]{start};
}
public DeweyNumber(DeweyNumber number) {
this.deweyNumber = Arrays.copyOf(number.deweyNumber, number.deweyNumber.length);
}
private DeweyNumber(int[] deweyNumber) {
this.deweyNumber = deweyNumber;
}
/**
* Checks whether this dewey number is compatible to the other dewey number.
*
* True iff this contains other as a prefix or iff they differ only in the last digit whereas
* the last digit of this is greater than the last digit of other.
*
* @param other The other dewey number to check compatibility against
* @return Whether this dewey number is compatible to the other dewey number
*/
public boolean isCompatibleWith(DeweyNumber other) {
if (length() > other.length()) {
// prefix case
for (int i = 0; i < other.length(); i++) {
if (other.deweyNumber[i] != deweyNumber[i]) {
return false;
}
}
return true;
} else if (length() == other.length()) {
// check init digits for equality
int lastIndex = length() - 1;
for (int i = 0; i < lastIndex; i++) {
if (other.deweyNumber[i] != deweyNumber[i]) {
return false;
}
}
// check that the last digit is greater or equal
return deweyNumber[lastIndex] >= other.deweyNumber[lastIndex];
} else {
return false;
}
}
public int length() {
return deweyNumber.length;
}
/**
* Creates a new dewey number from this such that its last digit is increased by
* one.
*
* @return A new dewey number derived from this whose last digit is increased by one
*/
public DeweyNumber increase() {
return increase(1);
}
/**
* Creates a new dewey number from this such that its last digit is increased by the supplied
* number
*
* @param times how many times to increase the Dewey number
* @return A new dewey number derived from this whose last digit is increased by given number
*/
public DeweyNumber increase(int times) {
int[] newDeweyNumber = Arrays.copyOf(deweyNumber, deweyNumber.length);
newDeweyNumber[deweyNumber.length - 1] += times;
return new DeweyNumber(newDeweyNumber);
}
/**
* Creates a new dewey number from this such that a 0 is appended as new last digit.
*
* @return A new dewey number which contains this as a prefix and has 0 as last digit
*/
public DeweyNumber addStage() {
int[] newDeweyNumber = Arrays.copyOf(deweyNumber, deweyNumber.length + 1);
return new DeweyNumber(newDeweyNumber);
}
@Override
public boolean equals(Object obj) {
if (obj instanceof DeweyNumber) {
DeweyNumber other = (DeweyNumber) obj;
return Arrays.equals(deweyNumber, other.deweyNumber);
} else {
return false;
}
}
@Override
public int hashCode() {
return Arrays.hashCode(deweyNumber);
}
@Override
public String toString() {
StringBuilder builder = new StringBuilder();
for (int i = 0; i < length() - 1; i++) {
builder.append(deweyNumber[i]).append(".");
}
if (length() > 0) {
builder.append(deweyNumber[length() - 1]);
}
return builder.toString();
}
/**
* Creates a dewey number from a string representation. The input string must be a dot separated
* string of integers.
*
* @param deweyNumberString Dot separated string of integers
* @return Dewey number generated from the given input string
*/
public static DeweyNumber fromString(final String deweyNumberString) {
String[] splits = deweyNumberString.split("\\.");
if (splits.length == 0) {
return new DeweyNumber(Integer.parseInt(deweyNumberString));
} else {
int[] deweyNumber = new int[splits.length];
for (int i = 0; i < splits.length; i++) {
deweyNumber[i] = Integer.parseInt(splits[i]);
}
return new DeweyNumber(deweyNumber);
}
}
/**
* A {@link TypeSerializer} for the {@link DeweyNumber} which serves as a version number.
*/
public static class DeweyNumberSerializer extends TypeSerializerSingleton<DeweyNumber> {
private static final long serialVersionUID = -5086792497034943656L;
private final IntSerializer elemSerializer = IntSerializer.INSTANCE;
@Override
public boolean isImmutableType() {
return false;
}
@Override
public DeweyNumber createInstance() {
return new DeweyNumber(1);
}
@Override
public DeweyNumber copy(DeweyNumber from) {
return new DeweyNumber(from);
}
@Override
public DeweyNumber copy(DeweyNumber from, DeweyNumber reuse) {
return copy(from);
}
@Override
public int getLength() {
return -1;
}
@Override
public void serialize(DeweyNumber record, DataOutputView target) throws IOException {
final int size = record.length();
target.writeInt(size);
for (int i = 0; i < size; i++) {
elemSerializer.serialize(record.deweyNumber[i], target);
}
}
@Override
public DeweyNumber deserialize(DataInputView source) throws IOException {
final int size = source.readInt();
int[] number = new int[size];
for (int i = 0; i < size; i++) {
number[i] = elemSerializer.deserialize(source);
}
return new DeweyNumber(number);
}
@Override
public DeweyNumber deserialize(DeweyNumber reuse, DataInputView source) throws IOException {
return deserialize(source);
}
@Override
public void copy(DataInputView source, DataOutputView target) throws IOException {
final int size = source.readInt();
target.writeInt(size);
for (int i = 0; i < size; i++) {
elemSerializer.copy(source, target);
}
}
@Override
public boolean equals(Object obj) {
return obj == this || obj.getClass().equals(getClass());
}
@Override
public boolean canEqual(Object obj) {
return true;
}
@Override
public int hashCode() {
return elemSerializer.hashCode();
}
}
}