142 lines
4.7 KiB
C++
142 lines
4.7 KiB
C++
/*
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**********************************************************************
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* Copyright (C) 2001, International Business Machines
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* Corporation and others. All Rights Reserved.
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**********************************************************************
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* Date Name Description
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* 05/24/01 aliu Creation.
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**********************************************************************
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*/
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#include "unicode/uchar.h"
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#include "unicode/titletrn.h"
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U_NAMESPACE_BEGIN
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/**
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* ID for this transliterator.
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*/
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const char TitlecaseTransliterator::_ID[] = "Any-Title";
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TitlecaseTransliterator::TitlecaseTransliterator(UnicodeFilter* adoptedFilter) :
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Transliterator(_ID, adoptedFilter) {
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// Need to look back 2 characters in the case of "can't"
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setMaximumContextLength(2);
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}
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/**
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* Destructor.
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*/
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TitlecaseTransliterator::~TitlecaseTransliterator() {}
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/**
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* Copy constructor.
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*/
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TitlecaseTransliterator::TitlecaseTransliterator(const TitlecaseTransliterator& o) :
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Transliterator(o) {}
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/**
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* Assignment operator.
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*/
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TitlecaseTransliterator& TitlecaseTransliterator::operator=(
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const TitlecaseTransliterator& o) {
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Transliterator::operator=(o);
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return *this;
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}
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/**
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* Transliterator API.
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*/
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Transliterator* TitlecaseTransliterator::clone(void) const {
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return new TitlecaseTransliterator(*this);
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}
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/**
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* Implements {@link Transliterator#handleTransliterate}.
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*/
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void TitlecaseTransliterator::handleTransliterate(
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Replaceable& text, UTransPosition& offsets,
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UBool isIncremental) const {
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// NOTE: This method contains some special case code to handle
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// apostrophes between alpha characters. We want to have
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// "can't" => "Can't" (not "Can'T"). This may be incorrect
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// for some locales, e.g., "l'arbre" => "L'Arbre" (?).
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// TODO: Revisit this.
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// Determine if there is a preceding letter character in the
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// left context (if there is any left context).
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UBool wasLastCharALetter = FALSE;
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if (offsets.start > offsets.contextStart) {
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UChar c = text.charAt(offsets.start - 1);
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// Handle the case "Can'|t", where the | marks the context
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// boundary. We only handle a single apostrophe.
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if (c == 0x0027 /*'*/ && (offsets.start-2) >= offsets.contextStart) {
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c = text.charAt(offsets.start - 2);
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}
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wasLastCharALetter = u_isalpha(c);
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}
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// The buffer used to batch up changes to be made
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UnicodeString buffer;
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int32_t bufStart = 0;
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int32_t bufLimit = -1;
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int32_t start;
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for (start = offsets.start; start < offsets.limit; ++start) {
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// For each character, if the preceding character was a
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// non-letter, and this character is a letter, then apply
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// the titlecase transformation. Otherwise apply the
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// lowercase transformation.
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UChar32 c = text.charAt(start);
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if (u_isalpha(c)) {
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UChar32 newChar;
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if (wasLastCharALetter) {
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newChar = u_tolower(c);
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} else {
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newChar = u_totitle(c);
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}
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if (c != newChar) {
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// This is the simple way of doing this:
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//text.replace(start, start+1,
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// String.valueOf((char) newChar));
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// Instead, we do something more complicated that
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// minimizes the number of calls to
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// Replaceable.replace(). We batch up the changes
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// we want to make in a buffer, recording
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// our position and dumping the buffer out when a
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// non-contiguous change arrives.
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if (bufLimit == start) {
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++bufLimit;
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// Fall through and append newChar below
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} else {
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if (buffer.length() > 0) {
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text.handleReplaceBetween(bufStart, bufLimit, buffer);
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buffer.truncate(0);
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}
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bufStart = start;
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bufLimit = start+1;
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// Fall through and append newChar below
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}
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buffer.append(newChar);
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}
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wasLastCharALetter = TRUE;
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} else if (c == 0x0027 /*'*/ && wasLastCharALetter) {
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// Ignore a single embedded apostrophe, so that "can't" =>
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// "Can't", not "Can'T".
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} else {
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wasLastCharALetter = FALSE;
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}
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}
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// assert(start == offsets.limit);
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offsets.start = start;
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if (buffer.length() > 0) {
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text.handleReplaceBetween(bufStart, bufLimit, buffer);
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}
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}
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U_NAMESPACE_END
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