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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;
import java.util.Comparator;
import java.util.Objects;
/**
* 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, 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 not 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() {
return stringHashCode(chars, offset, length);
}
/**
* @return the hash code of the given char sub-array, calculated by {@link String#hashCode()}
* specification
*/
public static int stringHashCode(char[] chars, int offset, int length) {
int end = offset + length;
int result = 0;
for (int i = offset; i < end; i++) {
result = 31 * 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) {
return Arrays.equals(
this.chars,
this.offset,
this.offset + this.length,
other.chars,
other.offset,
other.offset + other.length);
}
/** Signed int order comparison */
@Override
public int compareTo(CharsRef other) {
return Arrays.compare(
this.chars,
this.offset,
this.offset + this.length,
other.chars,
other.offset,
other.offset + 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
Objects.checkIndex(index, length);
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
Objects.checkFromToIndex(start, end, length);
return new CharsRef(chars, offset + start, end - start);
}
/**
* @deprecated This comparator is only a transition mechanism
*/
@Deprecated
private static final Comparator utf16SortedAsUTF8SortOrder =
new UTF16SortedAsUTF8Comparator();
/**
* @deprecated This comparator is only a transition mechanism
*/
@Deprecated
public static Comparator getUTF16SortedAsUTF8Comparator() {
return utf16SortedAsUTF8SortOrder;
}
/**
* @deprecated This comparator is only a transition mechanism
*/
@Deprecated
private static class UTF16SortedAsUTF8Comparator implements Comparator {
// Only singleton
private UTF16SortedAsUTF8Comparator() {}
@Override
public int compare(CharsRef a, CharsRef b) {
int aEnd = a.offset + a.length;
int bEnd = b.offset + b.length;
int i = Arrays.mismatch(a.chars, a.offset, aEnd, b.chars, b.offset, bEnd);
if (i >= 0 && i < Math.min(a.length, b.length)) {
// http://icu-project.org/docs/papers/utf16_code_point_order.html
char aChar = a.chars[a.offset + i];
char bChar = b.chars[b.offset + i];
/* 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 other
*
* The returned CharsRef will have a length of other.length and an offset of zero.
*/
public static CharsRef deepCopyOf(CharsRef other) {
return new CharsRef(
ArrayUtil.copyOfSubArray(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;
}
}