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/**
* Copyright 2010 - 2022 JetBrains s.r.o.
*
* Licensed 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 jetbrains.exodus.bindings;
import jetbrains.exodus.ArrayByteIterable;
import jetbrains.exodus.ByteIterable;
import jetbrains.exodus.ByteIterator;
import jetbrains.exodus.util.LightOutputStream;
import org.jetbrains.annotations.NotNull;
import java.io.ByteArrayInputStream;
/**
* {@linkplain ComparableBinding} for {@linkplain Integer} values.
*
* In addition to typical {@linkplain #intToEntry(int)} and {@linkplain #entryToInt(ByteIterable)} methods operating
* with {@code ByteIterables} of length {@code 4}, {@code IntegerBinding} has a pair of methods for
* serialization/deserialization of non-negative values to/from compressed entries:
* {@linkplain #intToCompressedEntry(int)} and {@linkplain #compressedEntryToInt(ByteIterable)}. The lower the value,
* the shorter the compressed entry. In some cases, compressed entries let you significantly decrease database size.
* Serialization of non-negative integers and longs to compressed entries also saves the order of values.
*
* @see ComparableBinding
*/
public class IntegerBinding extends ComparableBinding {
public static final IntegerBinding BINDING = new IntegerBinding();
private IntegerBinding() {
}
@Override
public Integer readObject(@NotNull final ByteArrayInputStream stream) {
return BindingUtils.readInt(stream);
}
@Override
public void writeObject(@NotNull final LightOutputStream output, @NotNull final Comparable object) {
output.writeUnsignedInt((Integer) object ^ 0x80000000);
}
/**
* De-serializes {@linkplain ByteIterable} entry to an {@code int} value.
* The entry should an output of {@linkplain #intToEntry(int)}.
*
* @param entry {@linkplain ByteIterable} instance
* @return de-serialized value
* @see #intToEntry(int)
* @see #compressedEntryToInt(ByteIterable)
* @see #intToCompressedEntry(int)
* @see #compressedEntryToSignedInt(ByteIterable)
* @see #signedIntToCompressedEntry(int)
*/
public static int entryToInt(@NotNull final ByteIterable entry) {
return (Integer) BINDING.entryToObject(entry);
}
/**
* Serializes {@code int} value to the {@linkplain ArrayByteIterable} entry.
*
* @param object value to serialize
* @return {@linkplain ArrayByteIterable} entry
* @see #entryToInt(ByteIterable)
* @see #compressedEntryToInt(ByteIterable)
* @see #intToCompressedEntry(int)
* @see #compressedEntryToSignedInt(ByteIterable)
* @see #signedIntToCompressedEntry(int)
*/
public static ArrayByteIterable intToEntry(final int object) {
return BINDING.objectToEntry(object);
}
/**
* De-serializes compressed {@linkplain ByteIterable} entry to an unsigned {@code int} value.
* The entry should be an output of {@linkplain #intToCompressedEntry(int)}.
*
* @param entry {@linkplain ByteIterable} instance
* @return de-serialized value
* @see #entryToInt(ByteIterable)
* @see #intToEntry(int)
* @see #intToCompressedEntry(int)
* @see #compressedEntryToSignedInt(ByteIterable)
* @see #signedIntToCompressedEntry(int)
*/
public static int compressedEntryToInt(@NotNull final ByteIterable entry) {
return readCompressed(entry.iterator());
}
/**
* Serializes unsigned {@code int} value to the compressed {@linkplain ArrayByteIterable} entry.
*
* @param object non-negative value to serialize
* @return {@linkplain ArrayByteIterable} entry
* @see #entryToInt(ByteIterable)
* @see #intToEntry(int)
* @see #compressedEntryToInt(ByteIterable)
* @see #compressedEntryToSignedInt(ByteIterable)
* @see #signedIntToCompressedEntry(int)
*/
public static ArrayByteIterable intToCompressedEntry(final int object) {
if (object < 0) {
throw new IllegalArgumentException();
}
final LightOutputStream output = new LightOutputStream(5);
writeCompressed(output, object);
return output.asArrayByteIterable();
}
/**
* De-serializes compressed {@linkplain ByteIterable} entry to a signed {@code int} value.
* The entry should be an output of {@linkplain #signedIntToCompressedEntry(int)}.
* ZigZag encoding is used,
* so it doesn't save the order of values like other {@code ComparableBindings} do.
*
* @param entry {@linkplain ByteIterable} instance
* @return de-serialized value
* @see #entryToInt(ByteIterable)
* @see #intToEntry(int)
* @see #compressedEntryToInt(ByteIterable)
* @see #intToCompressedEntry(int)
* @see #signedIntToCompressedEntry(int)
*/
public static int compressedEntryToSignedInt(@NotNull final ByteIterable entry) {
final int result = compressedEntryToInt(entry);
return (result >> 1) ^ (((result & 1) << 31) >> 31);
}
/**
* Serializes signed {@code int} value in the range {@code [Integer.MIN_VALUE/2..Integer.MAX_VALUE/2]}
* to the compressed {@linkplain ArrayByteIterable} entry.
*
ZigZag encoding is used,
* so it doesn't save the order of values like other {@code ComparableBindings} do.
*
* @param object value to serialize in the range {@code [Integer.MIN_VALUE/2..Integer.MAX_VALUE/2]}
* @return {@linkplain ArrayByteIterable} entry
* @see #entryToInt(ByteIterable)
* @see #intToEntry(int)
* @see #compressedEntryToInt(ByteIterable)
* @see #intToCompressedEntry(int)
* @see #compressedEntryToSignedInt(ByteIterable)
*/
public static ArrayByteIterable signedIntToCompressedEntry(final int object) {
return intToCompressedEntry((object << 1) ^ (object >> 31));
}
public static int readCompressed(@NotNull final ByteIterator iterator) {
final int firstByte = iterator.next() & 0xff;
int result = firstByte & 0x1f;
int byteLen = firstByte >> 5;
while (--byteLen >= 0) {
result = (result << 8) + (iterator.next() & 0xff);
}
return result;
}
public static int readCompressed(@NotNull final ByteArrayInputStream iterator) {
final int firstByte = iterator.read() & 0xff;
int result = firstByte & 0x1f;
int byteLen = firstByte >> 5;
while (--byteLen >= 0) {
result = (result << 8) + (iterator.read() & 0xff);
}
return result;
}
public static int readCompressed(@NotNull final byte[] bytes) {
final int firstByte = bytes[0] & 0xff;
int result = firstByte & 0x1f;
int byteLen = firstByte >> 5;
for (int i = 1; i <= byteLen; ++i) {
result = (result << 8) + (bytes[i] & 0xff);
}
return result;
}
public static void writeCompressed(@NotNull final LightOutputStream output, int i) {
writeCompressed(output, i, new int[4]);
}
public static void writeCompressed(@NotNull final LightOutputStream output, int i, final int[] bytes) {
for (int j = 0; j < 4; ++j) {
bytes[j] = i & 0xff;
i >>= 8;
}
int byteLen = 4;
while (byteLen > 0 && bytes[byteLen - 1] == 0) {
--byteLen;
}
int firstByte = byteLen << 5;
if (byteLen > 0) {
final int upperByte = bytes[byteLen - 1];
if (upperByte < 32) {
firstByte = (((firstByte >> 5) - 1) << 5) + upperByte;
--byteLen;
}
}
output.write(firstByte);
while (--byteLen >= 0) {
output.write(bytes[byteLen]);
}
}
}