Method ComputeByteDiff

Src/stringdiffs.cpp:853–1074

* @brief Compute begin1,begin2,end1,end2 to display byte difference between strings str1 & str2 * @param casitive [in] true for case-sensitive, false for case-insensitive * @param xwhite [in] This governs whether we handle whitespace specially (see WHITESPACE_COMPARE_ALL, WHITESPACE_IGNORE_CHANGE, WHITESPACE_IGNORE_ALL) * @param [out] begin return -1 if not found or pos of equal * @param [out]

 * Assumes whitespace is never leadbyte or trailbyte!
 */
void
stringdiffs::ComputeByteDiff(const String & str1, const String & str2, 
		   bool casitive, int xwhite, 
		   int begin[2], int end[2], bool equal)
{
	// Set to sane values
	// Also this way can distinguish if we set begin[0] to -1 for no diff in line
	begin[0] = begin[1] = end[0] = end[1] = 0;

	int len1 = static_cast<int>(str1.length());
	int len2 = static_cast<int>(str2.length());

	const tchar_t *pbeg1 = str1.c_str();
	const tchar_t *pbeg2 = str2.c_str();

	ICUBreakIterator *pIterCharBegin1 = ICUBreakIterator::getCharacterBreakIterator(reinterpret_cast<const UChar *>(pbeg1), static_cast<int32_t>(len1));
	ICUBreakIterator *pIterCharBegin2 = ICUBreakIterator::getCharacterBreakIterator<2>(reinterpret_cast<const UChar *>(pbeg2), static_cast<int32_t>(len2));
	ICUBreakIterator *pIterCharEnd1 = ICUBreakIterator::getCharacterBreakIterator<3>(reinterpret_cast<const UChar *>(pbeg1), static_cast<int32_t>(len1));
	ICUBreakIterator *pIterCharEnd2 = ICUBreakIterator::getCharacterBreakIterator<4>(reinterpret_cast<const UChar *>(pbeg2), static_cast<int32_t>(len2));
	
	if (len1 == 0 || len2 == 0)
	{
		if (len1 == len2)
		{
			begin[0] = begin[1] = end[0] = end[1] = -1;
		}
		else
		{
			end[0] = len1 - 1;
			end[1] = len2 - 1;
		}
		return;
	}

	// cursors from front, which we advance to beginning of difference
	const tchar_t *py1 = pbeg1;
	const tchar_t *py2 = pbeg2;

	// pen1,pen2 point to the last valid character (broken multibyte lead chars don't count)
	const tchar_t *pen1 = pbeg1 + (len1 > 0 ? pIterCharEnd1->preceding(len1) : 0);
	const tchar_t *pen2 = pbeg2 + (len2 > 0 ? pIterCharEnd2->preceding(len2) : 0);
	size_t glyphlenz1 = pbeg1 + len1 - pen1;
	size_t glyphlenz2 = pbeg2 + len2 - pen2;

	if (xwhite != WHITESPACE_COMPARE_ALL)
	{
		// Ignore leading and trailing whitespace
		// by advancing py1 and py2
		// and retreating pen1 and pen2
		while (py1 < pen1 && isSafeWhitespace(*py1))
			py1 = pbeg1 + pIterCharBegin1->next();
		while (py2 < pen2 && isSafeWhitespace(*py2))
			py2 = pbeg2 + pIterCharBegin2->next();
		if ((pen1 < pbeg1 + len1 - 1 || pen2 < pbeg2 + len2 -1)
			&& (pbeg1[len1] != pbeg2[len2]))
		{
			// mismatched broken multibyte ends
		}