com.ibm.icu.lang.CharSequences Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of icu4j Show documentation
Show all versions of icu4j Show documentation
International Component for Unicode for Java (ICU4J) is a mature, widely used Java library
providing Unicode and Globalization support
/*
********************************************************************************
* Copyright (C) 2010-2011, Google, International Business Machines Corporation *
* and others. All Rights Reserved. *
********************************************************************************
*/
package com.ibm.icu.lang;
/**
* A number of utilities for dealing with CharSequences and related classes.
* For accessing codepoints with a CharSequence, also see
*
* - {@link java.lang.Character#codePointAt(CharSequence, int)}
* - {@link java.lang.Character#codePointBefore(CharSequence, int)}
* - {@link java.lang.Character#codePointCount(CharSequence, int, int)}
* - {@link java.lang.Character#charCount(int)}
* - {@link java.lang.Character#offsetByCodePoints(CharSequence, int, int)}
* - {@link java.lang.Character#toChars(int, char[], int)}
* - {@link java.lang.Character#toCodePoint(char, char)}
*
* @author markdavis
* @internal
* @deprecated This API is ICU internal only.
*/
public class CharSequences {
// TODO
// compareTo(a, b);
// compareToIgnoreCase(a, b)
// contentEquals(a, b)
// contentEqualsIgnoreCase(a, b)
// contains(a, b) => indexOf >= 0
// endsWith(a, b)
// startsWith(a, b)
// lastIndexOf(a, b, fromIndex)
// indexOf(a, ch, fromIndex)
// lastIndexOf(a, ch, fromIndex);
// s.trim() => UnicodeSet.trim(CharSequence s); return a subsequence starting with the first character not in the set to the last character not in the set.
// add UnicodeSet.split(CharSequence s);
/**
* Find the longest n such that a[aIndex,n] = b[bIndex,n], and n is on a character boundary.
* @internal
* @deprecated This API is ICU internal only.
*/
public static int matchAfter(CharSequence a, CharSequence b, int aIndex, int bIndex) {
int i = aIndex, j = bIndex;
int alen = a.length();
int blen = b.length();
for (; i < alen && j < blen; ++i, ++j) {
char ca = a.charAt(i);
char cb = b.charAt(j);
if (ca != cb) {
break;
}
}
// if we failed a match make sure that we didn't match half a character
int result = i - aIndex;
if (result != 0 && !onCharacterBoundary(a, i) && !onCharacterBoundary(b, j)) {
--result; // backup
}
return result;
}
/**
* Count the code point length. Unpaired surrogates count as 1.
* @internal
* @deprecated This API is ICU internal only.
*/
public int codePointLength(CharSequence s) {
return Character.codePointCount(s, 0, s.length());
// int length = s.length();
// int result = length;
// for (int i = 1; i < length; ++i) {
// char ch = s.charAt(i);
// if (0xDC00 <= ch && ch <= 0xDFFF) {
// char ch0 = s.charAt(i-1);
// if (0xD800 <= ch && ch <= 0xDbFF) {
// --result;
// }
// }
// }
}
/**
* Utility function for comparing codepoint to string without generating new
* string.
*
* @internal
* @deprecated This API is ICU internal only.
*/
public static final boolean equals(int codepoint, CharSequence other) {
if (other == null) {
return false;
}
switch (other.length()) {
case 1: return codepoint == other.charAt(0);
case 2: return codepoint > 0xFFFF && codepoint == Character.codePointAt(other, 0);
default: return false;
}
}
/**
* @internal
* @deprecated This API is ICU internal only.
*/
public static final boolean equals(CharSequence other, int codepoint) {
return equals(codepoint, other);
}
/**
* Utility to compare a string to a code point.
* Same results as turning the code point into a string (with the [ugly] new StringBuilder().appendCodePoint(codepoint).toString())
* and comparing, but much faster (no object creation).
* Actually, there is one difference; a null compares as less.
* Note that this (=String) order is UTF-16 order -- *not* code point order.
*
* @internal
* @deprecated This API is ICU internal only.
*/
public static int compare(CharSequence string, int codePoint) {
if (codePoint < Character.MIN_CODE_POINT || codePoint > Character.MAX_CODE_POINT) {
throw new IllegalArgumentException();
}
int stringLength = string.length();
if (stringLength == 0) {
return -1;
}
char firstChar = string.charAt(0);
int offset = codePoint - Character.MIN_SUPPLEMENTARY_CODE_POINT;
if (offset < 0) { // BMP codePoint
int result = firstChar - codePoint;
if (result != 0) {
return result;
}
return stringLength - 1;
}
// non BMP
char lead = (char)((offset >>> 10) + Character.MIN_HIGH_SURROGATE);
int result = firstChar - lead;
if (result != 0) {
return result;
}
if (stringLength > 1) {
char trail = (char)((offset & 0x3ff) + Character.MIN_LOW_SURROGATE);
result = string.charAt(1) - trail;
if (result != 0) {
return result;
}
}
return stringLength - 2;
}
/**
* Utility to compare a string to a code point.
* Same results as turning the code point into a string and comparing, but much faster (no object creation).
* Actually, there is one difference; a null compares as less.
* Note that this (=String) order is UTF-16 order -- *not* code point order.
*
* @internal
* @deprecated This API is ICU internal only.
*/
public static int compare(int codepoint, CharSequence a) {
return -compare(a, codepoint);
}
/**
* Return the value of the first code point, if the string is exactly one code point. Otherwise return Integer.MAX_VALUE.
*
* @internal
* @deprecated This API is ICU internal only.
*/
public static int getSingleCodePoint(CharSequence s) {
int length = s.length();
if (length < 1 || length > 2) {
return Integer.MAX_VALUE;
}
int result = Character.codePointAt(s, 0);
return (result < 0x10000) == (length == 1) ? result : Integer.MAX_VALUE;
}
/**
* Utility function for comparing objects that may be null
* string.
*
* @internal
* @deprecated This API is ICU internal only.
*/
public static final boolean equals(T a, T b) {
return a == null ? b == null
: b == null ? false
: a.equals(b);
}
/**
* Utility for comparing the contents of CharSequences
*
* @internal
* @deprecated This API is ICU internal only.
*/
public static int compare(CharSequence a, CharSequence b) {
int alength = a.length();
int blength = b.length();
int min = alength <= blength ? alength : blength;
for (int i = 0; i < min; ++i) {
int diff = a.charAt(i) - b.charAt(i);
if (diff != 0) {
return diff;
}
}
return alength - blength;
}
/**
* Utility for comparing the contents of CharSequences
*
* @internal
* @deprecated This API is ICU internal only.
*/
public static boolean equalsChars(CharSequence a, CharSequence b) {
// do length test first for fast path
return a.length() == b.length() && compare(a,b) == 0;
}
/**
* Are we on a character boundary?
*
* @internal
* @deprecated This API is ICU internal only.
*/
public static boolean onCharacterBoundary(CharSequence s, int i) {
return i <= 0
|| i >= s.length()
|| !Character.isHighSurrogate(s.charAt(i-1))
|| !Character.isLowSurrogate(s.charAt(i));
}
/**
* Find code point in string.
*
* @internal
* @deprecated This API is ICU internal only.
*/
public static int indexOf(CharSequence s, int codePoint) {
int cp;
for (int i = 0; i < s.length(); i += Character.charCount(cp)) {
cp = Character.codePointAt(s, i);
if (cp == codePoint) {
return i;
}
}
return -1;
}
/**
* Utility function for simplified, more robust loops, such as:
*
* for (int codePoint : CharSequences.codePoints(string)) {
* doSomethingWith(codePoint);
* }
*
*
* @internal
* @deprecated This API is ICU internal only.
*/
public static int[] codePoints(CharSequence s) {
int[] result = new int[s.length()]; // in the vast majority of cases, the length is the same
int j = 0;
for (int i = 0; i < s.length(); ++i) {
char cp = s.charAt(i);
if (cp >= 0xDC00 && cp <= 0xDFFF && i != 0 ) { // hand-code for speed
char last = (char) result[j-1];
if (last >= 0xD800 && last <= 0xDBFF) {
// Note: j-1 is safe, because j can only be zero if i is zero. But i!=0 in this block.
result[j-1] = Character.toCodePoint(last, cp);
continue;
}
}
result[j++] = cp;
}
if (j == result.length) {
return result;
}
int[] shortResult = new int[j];
System.arraycopy(result, 0, shortResult, 0, j);
return shortResult;
}
private CharSequences() {
}
}