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| International friendly string comparison with case-order | |
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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.
*/
/*
* $Id: StringComparable.java 468655 2006-10-28 07:12:06Z minchau $
*/
import java.util.Vector;
import java.text.Collator;
import java.text.RuleBasedCollator;
import java.text.CollationElementIterator;
import java.util.Locale;
import java.text.CollationKey;
/**
* International friendly string comparison with case-order
* @author Igor Hersht, [email protected]
*/
public class StringComparable implements Comparable {
public final static int UNKNOWN_CASE = -1;
public final static int UPPER_CASE = 1;
public final static int LOWER_CASE = 2;
private String m_text;
private Locale m_locale;
private RuleBasedCollator m_collator;
private String m_caseOrder;
private int m_mask = 0xFFFFFFFF;
public StringComparable(final String text, final Locale locale, final Collator collator, final String caseOrder){
m_text = text;
m_locale = locale;
m_collator = (RuleBasedCollator)collator;
m_caseOrder = caseOrder;
m_mask = getMask(m_collator.getStrength());
}
public final static Comparable getComparator( final String text, final Locale locale, final Collator collator, final String caseOrder){
if((caseOrder == null) ||(caseOrder.length() == 0)){// no case-order specified
return ((RuleBasedCollator)collator).getCollationKey(text);
}else{
return new StringComparable(text, locale, collator, caseOrder);
}
}
public final String toString(){return m_text;}
public int compareTo(Object o) {
final String pattern = ((StringComparable)o).toString();
if(m_text.equals(pattern)){//Code-point equals
return 0;
}
final int savedStrength = m_collator.getStrength();
int comp = 0;
// Is there difference more significant than case-order?
if(((savedStrength == Collator.PRIMARY) || (savedStrength == Collator.SECONDARY))){
comp = m_collator.compare(m_text, pattern );
}else{// more than SECONDARY
m_collator.setStrength(Collator.SECONDARY);
comp = m_collator.compare(m_text, pattern );
m_collator.setStrength(savedStrength);
}
if(comp != 0){//Difference more significant than case-order
return comp ;
}
// No difference more significant than case-order.
// Find case difference
comp = getCaseDiff(m_text, pattern);
if(comp != 0){
return comp;
}else{// No case differences. Less significant difference could exist
return m_collator.compare(m_text, pattern );
}
}
private final int getCaseDiff (final String text, final String pattern){
final int savedStrength = m_collator.getStrength();
final int savedDecomposition = m_collator.getDecomposition();
m_collator.setStrength(Collator.TERTIARY);// not to ignore case
m_collator.setDecomposition(Collator.CANONICAL_DECOMPOSITION );// corresponds NDF
final int diff[] =getFirstCaseDiff (text, pattern, m_locale);
m_collator.setStrength(savedStrength);// restore
m_collator.setDecomposition(savedDecomposition); //restore
if(diff != null){
if((m_caseOrder).equals("upper-first")){
if(diff[0] == UPPER_CASE){
return -1;
}else{
return 1;
}
}else{// lower-first
if(diff[0] == LOWER_CASE){
return -1;
}else{
return 1;
}
}
}else{// No case differences
return 0;
}
}
private final int[] getFirstCaseDiff(final String text, final String pattern, final Locale locale){
final CollationElementIterator targIter = m_collator.getCollationElementIterator(text);
final CollationElementIterator patIter = m_collator.getCollationElementIterator(pattern);
int startTarg = -1;
int endTarg = -1;
int startPatt = -1;
int endPatt = -1;
final int done = getElement(CollationElementIterator.NULLORDER);
int patternElement = 0, targetElement = 0;
boolean getPattern = true, getTarget = true;
while (true) {
if (getPattern){
startPatt = patIter.getOffset();
patternElement = getElement(patIter.next());
endPatt = patIter.getOffset();
}
if ((getTarget)){
startTarg = targIter.getOffset();
targetElement = getElement(targIter.next());
endTarg = targIter.getOffset();
}
getTarget = getPattern = true;
if ((patternElement == done) ||( targetElement == done)) {
return null;
} else if (targetElement == 0) {
getPattern = false;
} else if (patternElement == 0) {
getTarget = false;
} else if (targetElement != patternElement) {// mismatch
if((startPatt < endPatt) && (startTarg < endTarg)){
final String subText = text.substring(startTarg, endTarg);
final String subPatt = pattern.substring(startPatt, endPatt);
final String subTextUp = subText.toUpperCase(locale);
final String subPattUp = subPatt.toUpperCase(locale);
if(m_collator.compare(subTextUp, subPattUp) != 0){ // not case diffference
continue;
}
int diff[] = {UNKNOWN_CASE, UNKNOWN_CASE};
if(m_collator.compare(subText, subTextUp) == 0){
diff[0] = UPPER_CASE;
}else if(m_collator.compare(subText, subText.toLowerCase(locale)) == 0){
diff[0] = LOWER_CASE;
}
if(m_collator.compare(subPatt, subPattUp) == 0){
diff[1] = UPPER_CASE;
}else if(m_collator.compare(subPatt, subPatt.toLowerCase(locale)) == 0){
diff[1] = LOWER_CASE;
}
if(((diff[0] == UPPER_CASE) && ( diff[1] == LOWER_CASE)) ||
((diff[0] == LOWER_CASE) && ( diff[1] == UPPER_CASE))){
return diff;
}else{// not case diff
continue;
}
}else{
continue;
}
}
}
}
// Return a mask for the part of the order we're interested in
private static final int getMask(final int strength) {
switch (strength) {
case Collator.PRIMARY:
return 0xFFFF0000;
case Collator.SECONDARY:
return 0xFFFFFF00;
default:
return 0xFFFFFFFF;
}
}
//get collation element with given strength
// from the element with max strength
private final int getElement(int maxStrengthElement){
return (maxStrengthElement & m_mask);
}
}//StringComparable
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