/*
* 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;
import java.util.Comparator;
/**
* Represents char[], as a slice (offset + length) into an existing char[].
* The {@link #chars} member should never be null; use
* {@link #EMPTY_CHARS} if necessary.
* @lucene.internal
*/
public final class CharsRef implements Comparable<CharsRef>, CharSequence, Cloneable {
/** An empty character array for convenience */
public static final char[] EMPTY_CHARS = new char[0];
/** The contents of the CharsRef. Should never be {@code null}. */
public char[] chars;
/** Offset of first valid character. */
public int offset;
/** Length of used characters. */
public int length;
/**
* Creates a new {@link CharsRef} initialized an empty array zero-length
*/
public CharsRef() {
this(EMPTY_CHARS, 0, 0);
}
/**
* Creates a new {@link CharsRef} initialized with an array of the given
* capacity
*/
public CharsRef(int capacity) {
chars = new char[capacity];
}
/**
* Creates a new {@link CharsRef} initialized with the given array, offset and
* length
*/
public CharsRef(char[] chars, int offset, int length) {
this.chars = chars;
this.offset = offset;
this.length = length;
assert isValid();
}
/**
* Creates a new {@link CharsRef} initialized with the given Strings character
* array
*/
public CharsRef(String string) {
this.chars = string.toCharArray();
this.offset = 0;
this.length = chars.length;
}
/**
* Returns a shallow clone of this instance (the underlying characters are
* <b>not</b> copied and will be shared by both the returned object and this
* object.
*
* @see #deepCopyOf
*/
@Override
public CharsRef clone() {
return new CharsRef(chars, offset, length);
}
@Override
public int hashCode() {
final int prime = 31;
int result = 0;
final int end = offset + length;
for (int i = offset; i < end; i++) {
result = prime * result + chars[i];
}
return result;
}
@Override
public boolean equals(Object other) {
if (other == null) {
return false;
}
if (other instanceof CharsRef) {
return this.charsEquals((CharsRef) other);
}
return false;
}
public boolean charsEquals(CharsRef other) {
if (length == other.length) {
int otherUpto = other.offset;
final char[] otherChars = other.chars;
final int end = offset + length;
for (int upto = offset; upto < end; upto++, otherUpto++) {
if (chars[upto] != otherChars[otherUpto]) {
return false;
}
}
return true;
} else {
return false;
}
}
/** Signed int order comparison */
@Override
public int compareTo(CharsRef other) {
if (this == other)
return 0;
final char[] aChars = this.chars;
int aUpto = this.offset;
final char[] bChars = other.chars;
int bUpto = other.offset;
final int aStop = aUpto + Math.min(this.length, other.length);
while (aUpto < aStop) {
int aInt = aChars[aUpto++];
int bInt = bChars[bUpto++];
if (aInt > bInt) {
return 1;
} else if (aInt < bInt) {
return -1;
}
}
// One is a prefix of the other, or, they are equal:
return this.length - other.length;
}
@Override
public String toString() {
return new String(chars, offset, length);
}
@Override
public int length() {
return length;
}
@Override
public char charAt(int index) {
// NOTE: must do a real check here to meet the specs of CharSequence
if (index < 0 || index >= length) {
throw new IndexOutOfBoundsException();
}
return chars[offset + index];
}
@Override
public CharSequence subSequence(int start, int end) {
// NOTE: must do a real check here to meet the specs of CharSequence
if (start < 0 || end > length || start > end) {
throw new IndexOutOfBoundsException();
}
return new CharsRef(chars, offset + start, end - start);
}
/** @deprecated This comparator is only a transition mechanism */
@Deprecated
private final static Comparator<CharsRef> utf16SortedAsUTF8SortOrder = new UTF16SortedAsUTF8Comparator();
/** @deprecated This comparator is only a transition mechanism */
@Deprecated
public static Comparator<CharsRef> getUTF16SortedAsUTF8Comparator() {
return utf16SortedAsUTF8SortOrder;
}
/** @deprecated This comparator is only a transition mechanism */
@Deprecated
private static class UTF16SortedAsUTF8Comparator implements Comparator<CharsRef> {
// Only singleton
private UTF16SortedAsUTF8Comparator() {};
@Override
public int compare(CharsRef a, CharsRef b) {
if (a == b)
return 0;
final char[] aChars = a.chars;
int aUpto = a.offset;
final char[] bChars = b.chars;
int bUpto = b.offset;
final int aStop = aUpto + Math.min(a.length, b.length);
while (aUpto < aStop) {
char aChar = aChars[aUpto++];
char bChar = bChars[bUpto++];
if (aChar != bChar) {
// http://icu-project.org/docs/papers/utf16_code_point_order.html
/* aChar != bChar, fix up each one if they're both in or above the surrogate range, then compare them */
if (aChar >= 0xd800 && bChar >= 0xd800) {
if (aChar >= 0xe000) {
aChar -= 0x800;
} else {
aChar += 0x2000;
}
if (bChar >= 0xe000) {
bChar -= 0x800;
} else {
bChar += 0x2000;
}
}
/* now aChar and bChar are in code point order */
return (int)aChar - (int)bChar; /* int must be 32 bits wide */
}
}
// One is a prefix of the other, or, they are equal:
return a.length - b.length;
}
}
/**
* Creates a new CharsRef that points to a copy of the chars from
* <code>other</code>
* <p>
* The returned CharsRef will have a length of other.length
* and an offset of zero.
*/
public static CharsRef deepCopyOf(CharsRef other) {
return new CharsRef(Arrays.copyOfRange(other.chars, other.offset, other.offset + other.length), 0, other.length);
}
/**
* Performs internal consistency checks.
* Always returns true (or throws IllegalStateException)
*/
public boolean isValid() {
if (chars == null) {
throw new IllegalStateException("chars is null");
}
if (length < 0) {
throw new IllegalStateException("length is negative: " + length);
}
if (length > chars.length) {
throw new IllegalStateException("length is out of bounds: " + length + ",chars.length=" + chars.length);
}
if (offset < 0) {
throw new IllegalStateException("offset is negative: " + offset);
}
if (offset > chars.length) {
throw new IllegalStateException("offset out of bounds: " + offset + ",chars.length=" + chars.length);
}
if (offset + length < 0) {
throw new IllegalStateException("offset+length is negative: offset=" + offset + ",length=" + length);
}
if (offset + length > chars.length) {
throw new IllegalStateException("offset+length out of bounds: offset=" + offset + ",length=" + length + ",chars.length=" + chars.length);
}
return true;
}
}