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/*
* 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.
*
* Important note: Unless otherwise noted, Lucene uses this class to represent terms that
* are encoded as UTF8 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 wrong, as it does not respect the correct character set and may return wrong
* results (depending on the platform's defaults)!
*
*
{@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, 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 capacity. Offset and length will
* both be zero.
*/
public BytesRef(int capacity) {
this.bytes = capacity == 0 ? EMPTY_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(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) {
return Arrays.equals(
this.bytes,
this.offset,
this.offset + this.length,
other.bytes,
other.offset,
other.offset + other.length);
}
/**
* Returns a shallow clone of this instance (the underlying bytes are not 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.
*
* 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 UTF-8 bytes, returning the resulting string. May throw an {@link
* AssertionError} or a {@link RuntimeException} if the data is not well-formed UTF-8.
*/
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, e.g. "[6c 75 63 65 6e 65]" */
@Override
public String toString() {
StringBuilder sb = new StringBuilder(2 + 3 * length);
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) {
return Arrays.compareUnsigned(
this.bytes,
this.offset,
this.offset + this.length,
other.bytes,
other.offset,
other.offset + other.length);
}
/**
* Creates a new BytesRef that points to a copy of the bytes from other
*
*
The returned BytesRef will have a length of other.length and an offset of zero.
*/
public static BytesRef deepCopyOf(BytesRef other) {
return new BytesRef(
ArrayUtil.copyOfSubArray(other.bytes, other.offset, other.offset + other.length),
0,
other.length);
}
/** 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;
}
}