com.ibm.icu.text.TitlecaseTransliterator 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
// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html#License
/*
* Copyright (C) 1996-2011, International Business Machines Corporation and
* others. All Rights Reserved.
*
*/
package com.ibm.icu.text;
import com.ibm.icu.impl.UCaseProps;
import com.ibm.icu.lang.UCharacter;
import com.ibm.icu.util.ULocale;
/**
* A transliterator that converts all letters (as defined by
* UCharacter.isLetter()) to lower case, except for those
* letters preceded by non-letters. The latter are converted to title
* case using UCharacter.toTitleCase().
* @author Alan Liu
*/
class TitlecaseTransliterator extends Transliterator {
static final String _ID = "Any-Title";
// TODO: Add variants for tr/az, lt, default = default locale: ICU ticket #12720
/**
* System registration hook.
*/
static void register() {
Transliterator.registerFactory(_ID, new Transliterator.Factory() {
@Override
public Transliterator getInstance(String ID) {
return new TitlecaseTransliterator(ULocale.US);
}
});
registerSpecialInverse("Title", "Lower", false);
}
private final ULocale locale;
private final UCaseProps csp;
private ReplaceableContextIterator iter;
private StringBuilder result;
private int caseLocale;
/**
* Constructs a transliterator.
*/
public TitlecaseTransliterator(ULocale loc) {
super(_ID, null);
locale = loc;
// Need to look back 2 characters in the case of "can't"
setMaximumContextLength(2);
csp=UCaseProps.INSTANCE;
iter=new ReplaceableContextIterator();
result = new StringBuilder();
caseLocale = UCaseProps.getCaseLocale(locale);
}
/**
* Implements {@link Transliterator#handleTransliterate}.
*/
@Override
protected synchronized void handleTransliterate(Replaceable text,
Position offsets, boolean isIncremental) {
// TODO reimplement, see ustrcase.c
// using a real word break iterator
// instead of just looking for a transition between cased and uncased characters
// call CaseMapTransliterator::handleTransliterate() for lowercasing? (set fMap)
// needs to take isIncremental into account because case mappings are context-sensitive
// also detect when lowercasing function did not finish because of context
if (offsets.start >= offsets.limit) {
return;
}
// case type: >0 cased (UCaseProps.LOWER etc.) ==0 uncased <0 case-ignorable
int type;
// Our mode; we are either converting letter toTitle or
// toLower.
boolean doTitle = true;
// Determine if there is a preceding context of cased case-ignorable*,
// in which case we want to start in toLower mode. If the
// prior context is anything else (including empty) then start
// in toTitle mode.
int c, start;
for (start = offsets.start - 1; start >= offsets.contextStart; start -= UTF16.getCharCount(c)) {
c = text.char32At(start);
type=csp.getTypeOrIgnorable(c);
if(type>0) { // cased
doTitle=false;
break;
} else if(type==0) { // uncased but not ignorable
break;
}
// else (type<0) case-ignorable: continue
}
// Convert things after a cased character toLower; things
// after a uncased, non-case-ignorable character toTitle. Case-ignorable
// characters are copied directly and do not change the mode.
iter.setText(text);
iter.setIndex(offsets.start);
iter.setLimit(offsets.limit);
iter.setContextLimits(offsets.contextStart, offsets.contextLimit);
result.setLength(0);
// Walk through original string
// If there is a case change, modify corresponding position in replaceable
int delta;
while((c=iter.nextCaseMapCP())>=0) {
type=csp.getTypeOrIgnorable(c);
if(type>=0) { // not case-ignorable
if(doTitle) {
c=csp.toFullTitle(c, iter, result, caseLocale);
} else {
c=csp.toFullLower(c, iter, result, caseLocale);
}
doTitle = type==0; // doTitle=isUncased
if(iter.didReachLimit() && isIncremental) {
// the case mapping function tried to look beyond the context limit
// wait for more input
offsets.start=iter.getCaseMapCPStart();
return;
}
/* decode the result */
if(c<0) {
/* c mapped to itself, no change */
continue;
} else if(c<=UCaseProps.MAX_STRING_LENGTH) {
/* replace by the mapping string */
delta=iter.replace(result.toString());
result.setLength(0);
} else {
/* replace by single-code point mapping */
delta=iter.replace(UTF16.valueOf(c));
}
if(delta!=0) {
offsets.limit += delta;
offsets.contextLimit += delta;
}
}
}
offsets.start = offsets.limit;
}
// NOTE: normally this would be static, but because the results vary by locale....
SourceTargetUtility sourceTargetUtility = null;
/* (non-Javadoc)
* @see com.ibm.icu.text.Transliterator#addSourceTargetSet(com.ibm.icu.text.UnicodeSet, com.ibm.icu.text.UnicodeSet, com.ibm.icu.text.UnicodeSet)
*/
@Override
public void addSourceTargetSet(UnicodeSet inputFilter, UnicodeSet sourceSet, UnicodeSet targetSet) {
synchronized (this) {
if (sourceTargetUtility == null) {
sourceTargetUtility = new SourceTargetUtility(new Transform() {
@Override
public String transform(String source) {
return UCharacter.toTitleCase(locale, source, null);
}
});
}
}
sourceTargetUtility.addSourceTargetSet(this, inputFilter, sourceSet, targetSet);
}
}