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Add {start,end}with_lower methods to StringRef.

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startswith_lower is ocassionally useful and I think worth adding.
endwith_lower is added for completeness.

Differential Revision: http://llvm-reviews.chandlerc.com/D2041

llvm-svn: 193706
This commit is contained in:
Rui Ueyama
2013-10-30 18:32:26 +00:00
parent c1be9c16bc
commit 00e24e48b6
3 changed files with 53 additions and 5 deletions
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29
llvm/lib/Support/StringRef.cpp
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@@ -37,20 +37,39 @@ static bool ascii_isdigit(char x) {
return x >= '0' && x <= '9';
}
/// compare_lower - Compare strings, ignoring case.
int StringRef::compare_lower(StringRef RHS) const {
for (size_t I = 0, E = min(Length, RHS.Length); I != E; ++I) {
unsigned char LHC = ascii_tolower(Data[I]);
unsigned char RHC = ascii_tolower(RHS.Data[I]);
// strncasecmp() is not available on non-POSIX systems, so define an
// alternative function here.
static int ascii_strncasecmp(const char *LHS, const char *RHS, size_t Length) {
for (size_t I = 0; I < Length; ++I) {
unsigned char LHC = ascii_tolower(LHS[I]);
unsigned char RHC = ascii_tolower(RHS[I]);
if (LHC != RHC)
return LHC < RHC ? -1 : 1;
}
return 0;
}
/// compare_lower - Compare strings, ignoring case.
int StringRef::compare_lower(StringRef RHS) const {
if (int Res = ascii_strncasecmp(Data, RHS.Data, min(Length, RHS.Length)))
return Res;
if (Length == RHS.Length)
return 0;
return Length < RHS.Length ? -1 : 1;
}
/// Check if this string starts with the given \p Prefix, ignoring case.
bool StringRef::startswith_lower(StringRef Prefix) const {
return Length >= Prefix.Length &&
ascii_strncasecmp(Data, Prefix.Data, Prefix.Length) == 0;
}
/// Check if this string ends with the given \p Suffix, ignoring case.
bool StringRef::endswith_lower(StringRef Suffix) const {
return Length >= Suffix.Length &&
ascii_strncasecmp(end() - Suffix.Length, Suffix.Data, Suffix.Length) == 0;
}
/// compare_numeric - Compare strings, handle embedded numbers.
int StringRef::compare_numeric(StringRef RHS) const {
for (size_t I = 0, E = min(Length, RHS.Length); I != E; ++I) {