wild card matching in text string - regex

Question

My friend give this wild card(*) matching algorithm . Here is the code .
//This function compares text strings, one of which can have wildcards ('*').
//
BOOL GeneralTextCompare(
char * pTameText, // A string without wildcards
char * pWildText, // A (potentially) corresponding string with wildcards
BOOL bCaseSensitive = FALSE, // By default, match on 'X' vs 'x'
char cAltTerminator = '\0' // For function names, for example, you can stop at the first '('
)
{
BOOL bMatch = TRUE;
char * pAfterLastWild = NULL; // The location after the last '*', if we’ve encountered one
char * pAfterLastTame = NULL; // The location in the tame string, from which we started after last wildcard
char t, w;
// Walk the text strings one character at a time.
while (1)
{
t = *pTameText;
w = *pWildText;
// How do you match a unique text string?
if (!t || t == cAltTerminator)
{
// Easy: unique up on it!
if (!w || w == cAltTerminator)
{
break; // "x" matches "x"
}
else if (w == '*')
{
pWildText++;
continue; // "x*" matches "x" or "xy"
}
else if (pAfterLastTame)
{
if (!(*pAfterLastTame) || *pAfterLastTame == cAltTerminator)
{
bMatch = FALSE;
break;
}
pTameText = pAfterLastTame++;
pWildText = pAfterLastWild;
continue;
}
bMatch = FALSE;
break; // "x" doesn't match "xy"
}
else
{
if (!bCaseSensitive)
{
// Lowercase the characters to be compared.
if (t >= 'A' && t <= 'Z')
{
t += ('a' - 'A');
}
if (w >= 'A' && w <= 'Z')
{
w += ('a' - 'A');
}
}
// How do you match a tame text string?
if (t != w)
{
// The tame way: unique up on it!
if (w == '*')
{
pAfterLastWild = ++pWildText;
pAfterLastTame = pTameText;
w = *pWildText;
if (!w || w == cAltTerminator)
{
break; // "*" matches "x"
}
continue; // "*y" matches "xy"
}
else if (pAfterLastWild)
{
if (pAfterLastWild != pWildText)
{
pWildText = pAfterLastWild;
w = *pWildText;
if (!bCaseSensitive && w >= 'A' && w <= 'Z')
{
w += ('a' - 'A');
}
if (t == w)
{
pWildText++;
}
}
pTameText++;
continue; // "*sip*" matches "mississippi"
}
else
{
bMatch = FALSE;
break; // "x" doesn't match "y"
}
}
}
pTameText++;
pWildText++;
}
return bMatch;
}
This algo works as follow (according to me)
mississippi *sip*
mississippi sip*
ississippi sip*
ssissippi sip*
sissippi ip*
sissippi sip* pAfterLastWild is used to restore the location
issippi ip*
ssippi p*
ssippi sip* again pAfterLastWild is used here.
sippi ip*
sippi sip* here also.
ippi ip*
ppi p*
pi *
i *
I am not able to figure out why pAfterLastTame is needed and what does this piece of code is doing here as i am not able to find use of it .
else if (pAfterLastTame)
{
if (!(*pAfterLastTame) || *pAfterLastTame == cAltTerminator)
{
bMatch = FALSE;
break;
}
pTameText = pAfterLastTame++;
pWildText = pAfterLastWild;
continue;
}
This algo is pretty fast as number of comparisons are equal to size of tameString (correct me i am wrong) .
Does any one know more efficient algorithm than this ??