Function lstrcasestr

source/util.cpp:800–894

LPTSTR lstrcasestr(LPCTSTR phaystack, LPCTSTR pneedle)
// This is the locale-obeying variant of strcasestr.  It uses CharUpper/Lower in place of toupper/lower,
// which sees chars like ä as the same as Ä (depending on code page/locale).  This function is about
// 1 to 8 times slower than strcasestr() depending on factors such as how many partial matches for needle
// are in haystack.
// License: GNU GPL
// Copyright (C) 1994,1996,1997,1998,1999,2000 Free Software Foundation, Inc.
// See strcasestr() for more comments.
{
	register const TBYTE *haystack, *needle;
	register unsigned bl, bu, cl, cu;
	
	haystack = (const TBYTE *) phaystack;
	needle = (const TBYTE *) pneedle;

	bl = (UINT)ltolower(*needle);
	if (bl != 0)
	{
		// Scan haystack until the first character of needle is found:
		bu = (UINT)(size_t)ltoupper(bl);
		haystack--;				/* possible ANSI violation */
		do
		{
			cl = *++haystack;
			if (cl == '\0')
				goto ret0;
		}
		while ((cl != bl) && (cl != bu));

		// See if the rest of needle is a one-for-one match with this part of haystack:
		cl = (UINT)ltolower(*++needle);
		if (cl == '\0')  // Since needle consists of only one character, it is already a match as found above.
			goto foundneedle;
		cu = (UINT)ltoupper(cl);
		++needle;
		goto jin;
		
		for (;;)
		{
			register unsigned a;
			register const TBYTE *rhaystack, *rneedle;
			do
			{
				a = *++haystack;
				if (a == '\0')
					goto ret0;
				if ((a == bl) || (a == bu))
					break;
				a = *++haystack;
				if (a == '\0')
					goto ret0;
shloop:
				;
			}
			while ((a != bl) && (a != bu));

jin:
			a = *++haystack;