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Implements StringRef::compare with bounds. It is behaves similarly to strncmp(). Unit tests also included. 

llvm-svn: 129582
This commit is contained in:
Lenny Maiorani 2011-04-15 17:56:50 +00:00
parent a236485b1f
commit fad9d95722
3 changed files with 40 additions and 0 deletions
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6
llvm/include/llvm/ADT/StringRef.h
View File

@ -125,6 +125,12 @@ namespace llvm {
return Length < RHS.Length ? -1 : 1;
}
/// compare - Compare two strings; the result is -1, 0, or 1 if this string
/// is lexicographically less than, equal to, or greater than the \arg RHS.
/// This is different than compare with no size specified as it only
/// compares at most the first n bytes.
int compare(StringRef RHS, size_t n) const;
/// compare_lower - Compare two strings, ignoring case.
int compare_lower(StringRef RHS) const;

21
llvm/lib/Support/StringRef.cpp
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@ -29,6 +29,27 @@ static bool ascii_isdigit(char x) {
return x >= '0' && x <= '9';
}
/// compare - Compare two strings; the result is -1, 0, or 1 if this string
/// is lexicographically less than, equal to, or greater than the \arg RHS.
/// This is different than compare with no size specified as it only
/// compares at most the first n bytes.
int StringRef::compare(StringRef RHS, size_t n) const {
// Check the prefix for a mismatch.
size_t maxToCmp = min(Length, RHS.Length);
maxToCmp = min(maxToCmp, n);
if (int Res = memcmp(Data, RHS.Data, maxToCmp))
return Res < 0 ? -1 : 1;
// Otherwise the prefixes match, so we only need to check the lengths.
// Be mindful that if the n is less than or equal to the length of either
// string, that is the same as the strings matching because in that case
// we only care about the prefix.
if (((n <= Length) && (n <= RHS.Length)) ||
(Length == RHS.Length))
return 0;
return Length < RHS.Length ? -1 : 1;
}
/// 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) {

13
llvm/unittests/ADT/StringRefTest.cpp
View File

@ -55,6 +55,19 @@ TEST(StringRefTest, StringOps) {
EXPECT_EQ( 1, StringRef("aab").compare("aa"));
EXPECT_EQ( 1, StringRef("\xFF").compare("\1"));
EXPECT_EQ(-1, StringRef("aab").compare("aad", 3));
EXPECT_EQ( 0, StringRef("aab").compare("aab", 3));
EXPECT_EQ( 1, StringRef("aab").compare("aaa", 3));
EXPECT_EQ(-1, StringRef("aab").compare("aabb", 4));
EXPECT_EQ( 1, StringRef("aab").compare("aa", 3));
EXPECT_EQ( 1, StringRef("\xFF").compare("\1", 3));
EXPECT_EQ( 0, StringRef("aab").compare("aad", 2));
EXPECT_EQ( 0, StringRef("aab").compare("aab", 2));
EXPECT_EQ( 0, StringRef("aab").compare("aab", 4));
EXPECT_EQ( 0, StringRef("aab").compare("aaa", 2));
EXPECT_EQ( 0, StringRef("aab").compare("aabb", 3));
EXPECT_EQ( 0, StringRef("aab").compare("aa", 2));
EXPECT_EQ(-1, StringRef("AaB").compare_lower("aAd"));
EXPECT_EQ( 0, StringRef("AaB").compare_lower("aab"));
EXPECT_EQ( 1, StringRef("AaB").compare_lower("AAA"));