package org.apache.lucene.util;
/*
* 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.
*/
import java.util.Comparator;
/** 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)!
*/
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();
copyChars(text);
}
/**
* Copies the UTF8 bytes for this string.
*
* @param text Must be well-formed unicode text, with no
* unpaired surrogates or invalid UTF16 code units.
*/
public void copyChars(CharSequence text) {
assert offset == 0; // TODO broken if offset != 0
UnicodeUtil.UTF16toUTF8(text, 0, text.length(), this);
}
/**
* 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>It is defined as:
* <pre class="prettyprint">
* int hash = 0;
* for (int i = offset; i < offset + length; i++) {
* hash = 31*hash + bytes[i];
* }
* </pre>
*/
@Override
public int hashCode() {
int hash = 0;
final int end = offset + length;
for(int i=offset;i<end;i++) {
hash = 31 * hash + bytes[i];
}
return hash;
}
@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 CharsRef ref = new CharsRef(length);
UnicodeUtil.UTF8toUTF16(bytes, offset, length, ref);
return ref.toString();
}
/** 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();
}
/**
* Copies the bytes from the given {@link BytesRef}
* <p>
* NOTE: if this would exceed the array size, this method creates a
* new reference array.
*/
public void copyBytes(BytesRef other) {
if (bytes.length - offset < other.length) {
bytes = new byte[other.length];
offset = 0;
}
System.arraycopy(other.bytes, other.offset, bytes, offset, other.length);
length = other.length;
}
/**
* Appends the bytes from the given {@link BytesRef}
* <p>
* NOTE: if this would exceed the array size, this method creates a
* new reference array.
*/
public void append(BytesRef other) {
int newLen = length + other.length;
if (bytes.length - offset < newLen) {
byte[] newBytes = new byte[newLen];
System.arraycopy(bytes, offset, newBytes, 0, length);
offset = 0;
bytes = newBytes;
}
System.arraycopy(other.bytes, other.offset, bytes, length+offset, other.length);
length = newLen;
}
/**
* Used to grow the reference array.
*
* In general this should not be used as it does not take the offset into account.
* @lucene.internal */
public void grow(int newLength) {
assert offset == 0; // NOTE: senseless if offset != 0
bytes = ArrayUtil.grow(bytes, newLength);
}
/** Unsigned byte order comparison */
@Override
public int compareTo(BytesRef other) {
return utf8SortedAsUnicodeSortOrder.compare(this, other);
}
private final static Comparator<BytesRef> utf8SortedAsUnicodeSortOrder = new UTF8SortedAsUnicodeComparator();
public static Comparator<BytesRef> getUTF8SortedAsUnicodeComparator() {
return utf8SortedAsUnicodeSortOrder;
}
private static class UTF8SortedAsUnicodeComparator implements Comparator<BytesRef> {
// Only singleton
private UTF8SortedAsUnicodeComparator() {};
@Override
public int compare(BytesRef a, BytesRef b) {
final byte[] aBytes = a.bytes;
int aUpto = a.offset;
final byte[] bBytes = b.bytes;
int bUpto = b.offset;
final int aStop = aUpto + Math.min(a.length, b.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 a.length - b.length;
}
}
/** @deprecated This comparator is only a transition mechanism */
@Deprecated
private final static Comparator<BytesRef> utf8SortedAsUTF16SortOrder = new UTF8SortedAsUTF16Comparator();
/** @deprecated This comparator is only a transition mechanism */
@Deprecated
public static Comparator<BytesRef> getUTF8SortedAsUTF16Comparator() {
return utf8SortedAsUTF16SortOrder;
}
/** @deprecated This comparator is only a transition mechanism */
@Deprecated
private static class UTF8SortedAsUTF16Comparator implements Comparator<BytesRef> {
// Only singleton
private UTF8SortedAsUTF16Comparator() {};
@Override
public int compare(BytesRef a, BytesRef b) {
final byte[] aBytes = a.bytes;
int aUpto = a.offset;
final byte[] bBytes = b.bytes;
int bUpto = b.offset;
final int aStop;
if (a.length < b.length) {
aStop = aUpto + a.length;
} else {
aStop = aUpto + b.length;
}
while(aUpto < aStop) {
int aByte = aBytes[aUpto++] & 0xff;
int bByte = bBytes[bUpto++] & 0xff;
if (aByte != bByte) {
// See http://icu-project.org/docs/papers/utf16_code_point_order.html#utf-8-in-utf-16-order
// We know the terms are not equal, but, we may
// have to carefully fixup the bytes at the
// difference to match UTF16's sort order:
// NOTE: instead of moving supplementary code points (0xee and 0xef) to the unused 0xfe and 0xff,
// we move them to the unused 0xfc and 0xfd [reserved for future 6-byte character sequences]
// this reserves 0xff for preflex's term reordering (surrogate dance), and if unicode grows such
// that 6-byte sequences are needed we have much bigger problems anyway.
if (aByte >= 0xee && bByte >= 0xee) {
if ((aByte & 0xfe) == 0xee) {
aByte += 0xe;
}
if ((bByte&0xfe) == 0xee) {
bByte += 0xe;
}
}
return aByte - bByte;
}
}
// One is a prefix of the other, or, they are equal:
return a.length - b.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.copyBytes(other);
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;
}
}