/*
* 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.lucene.util;
import java.util.Arrays;
/** Represents byte[], as a slice (offset + length) into an
* existing byte[]. The {@link #bytes} member should never be null;
* use {@link #EMPTY_BYTES} if necessary.
*
* <p><b>Important note:</b> Unless otherwise noted, Lucene uses this class to
* represent terms that are encoded as <b>UTF8</b> bytes in the index. To
* convert them to a Java {@link String} (which is UTF16), use {@link #utf8ToString}.
* Using code like {@code new String(bytes, offset, length)} to do this
* is <b>wrong</b>, as it does not respect the correct character set
* and may return wrong results (depending on the platform's defaults)!
*
* <p>{@code BytesRef} implements {@link Comparable}. The underlying byte arrays
* are sorted lexicographically, numerically treating elements as unsigned.
* This is identical to Unicode codepoint order.
*/
public final class BytesRef implements Comparable<BytesRef>,Cloneable {
/** An empty byte array for convenience */
public static final byte[] EMPTY_BYTES = new byte[0];
/** The contents of the BytesRef. Should never be {@code null}. */
public byte[] bytes;
/** Offset of first valid byte. */
public int offset;
/** Length of used bytes. */
public int length;
/** Create a BytesRef with {@link #EMPTY_BYTES} */
public BytesRef() {
this(EMPTY_BYTES);
}
/** This instance will directly reference bytes w/o making a copy.
* bytes should not be null.
*/
public BytesRef(byte[] bytes, int offset, int length) {
this.bytes = bytes;
this.offset = offset;
this.length = length;
assert isValid();
}
/** This instance will directly reference bytes w/o making a copy.
* bytes should not be null */
public BytesRef(byte[] bytes) {
this(bytes, 0, bytes.length);
}
/**
* Create a BytesRef pointing to a new array of size <code>capacity</code>.
* Offset and length will both be zero.
*/
public BytesRef(int capacity) {
this.bytes = new byte[capacity];
}
/**
* Initialize the byte[] from the UTF8 bytes
* for the provided String.
*
* @param text This must be well-formed
* unicode text, with no unpaired surrogates.
*/
public BytesRef(CharSequence text) {
this(new byte[UnicodeUtil.maxUTF8Length(text.length())]);
length = UnicodeUtil.UTF16toUTF8(text, 0, text.length(), bytes);
}
/**
* Expert: compares the bytes against another BytesRef,
* returning true if the bytes are equal.
*
* @param other Another BytesRef, should not be null.
* @lucene.internal
*/
public boolean bytesEquals(BytesRef other) {
assert other != null;
if (length == other.length) {
int otherUpto = other.offset;
final byte[] otherBytes = other.bytes;
final int end = offset + length;
for(int upto=offset;upto<end;upto++,otherUpto++) {
if (bytes[upto] != otherBytes[otherUpto]) {
return false;
}
}
return true;
} else {
return false;
}
}
/**
* Returns a shallow clone of this instance (the underlying bytes are
* <b>not</b> copied and will be shared by both the returned object and this
* object.
*
* @see #deepCopyOf
*/
@Override
public BytesRef clone() {
return new BytesRef(bytes, offset, length);
}
/** Calculates the hash code as required by TermsHash during indexing.
* <p> This is currently implemented as MurmurHash3 (32
* bit), using the seed from {@link
* StringHelper#GOOD_FAST_HASH_SEED}, but is subject to
* change from release to release. */
@Override
public int hashCode() {
return StringHelper.murmurhash3_x86_32(this, StringHelper.GOOD_FAST_HASH_SEED);
}
@Override
public boolean equals(Object other) {
if (other == null) {
return false;
}
if (other instanceof BytesRef) {
return this.bytesEquals((BytesRef) other);
}
return false;
}
/** Interprets stored bytes as UTF8 bytes, returning the
* resulting string */
public String utf8ToString() {
final char[] ref = new char[length];
final int len = UnicodeUtil.UTF8toUTF16(bytes, offset, length, ref);
return new String(ref, 0, len);
}
/** Returns hex encoded bytes, eg [0x6c 0x75 0x63 0x65 0x6e 0x65] */
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append('[');
final int end = offset + length;
for(int i=offset;i<end;i++) {
if (i > offset) {
sb.append(' ');
}
sb.append(Integer.toHexString(bytes[i]&0xff));
}
sb.append(']');
return sb.toString();
}
/** Unsigned byte order comparison */
@Override
public int compareTo(BytesRef other) {
// TODO: Once we are on Java 9 replace this by java.util.Arrays#compareUnsigned()
// which is implemented by a Hotspot intrinsic! Also consider building a
// Multi-Release-JAR!
final byte[] aBytes = this.bytes;
int aUpto = this.offset;
final byte[] bBytes = other.bytes;
int bUpto = other.offset;
final int aStop = aUpto + Math.min(this.length, other.length);
while(aUpto < aStop) {
int aByte = aBytes[aUpto++] & 0xff;
int bByte = bBytes[bUpto++] & 0xff;
int diff = aByte - bByte;
if (diff != 0) {
return diff;
}
}
// One is a prefix of the other, or, they are equal:
return this.length - other.length;
}
/**
* Creates a new BytesRef that points to a copy of the bytes from
* <code>other</code>
* <p>
* The returned BytesRef will have a length of other.length
* and an offset of zero.
*/
public static BytesRef deepCopyOf(BytesRef other) {
BytesRef copy = new BytesRef();
copy.bytes = Arrays.copyOfRange(other.bytes, other.offset, other.offset + other.length);
copy.offset = 0;
copy.length = other.length;
return copy;
}
/**
* Performs internal consistency checks.
* Always returns true (or throws IllegalStateException)
*/
public boolean isValid() {
if (bytes == null) {
throw new IllegalStateException("bytes is null");
}
if (length < 0) {
throw new IllegalStateException("length is negative: " + length);
}
if (length > bytes.length) {
throw new IllegalStateException("length is out of bounds: " + length + ",bytes.length=" + bytes.length);
}
if (offset < 0) {
throw new IllegalStateException("offset is negative: " + offset);
}
if (offset > bytes.length) {
throw new IllegalStateException("offset out of bounds: " + offset + ",bytes.length=" + bytes.length);
}
if (offset + length < 0) {
throw new IllegalStateException("offset+length is negative: offset=" + offset + ",length=" + length);
}
if (offset + length > bytes.length) {
throw new IllegalStateException("offset+length out of bounds: offset=" + offset + ",length=" + length + ",bytes.length=" + bytes.length);
}
return true;
}
}