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string: add variants for char16_t/char16_t strncmp
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Technically, this is still binary compare with no locale-specific
ordering knowledge. But takes Unicode representation of UTF-16 surrogate
pairs when comparing.

Signed-off-by: Simon Rozman <simon.rozman@amebis.si>
This commit is contained in:
Simon Rozman
2025-12-03 12:49:10 +01:00
parent f9b7dba542
commit 655bee3692
1 changed files with 97 additions and 0 deletions
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97
include/stdex/string.hpp
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@@ -1066,6 +1066,103 @@ namespace stdex
reinterpret_cast<const utf16_t*>(str2), N2);
}
///
/// Binary compare two strings
///
/// \param[in] str1 String 1
/// \param[in] count1 String 1 code unit count limit
/// \param[in] str2 String 2
/// \param[in] count2 String 2 code unit count limit
///
/// \return Negative if str1<str2; positive if str1>str2; zero if str1==str2
///
inline int strncmp(
_In_reads_or_z_opt_(count1) const utf16_t* str1, _In_ size_t count1,
_In_reads_or_z_opt_(count2) const utf16_t* str2, _In_ size_t count2)
{
stdex_assert(str1 || !count1);
stdex_assert(str2 || !count2);
for (size_t i = 0, j = 0; ;) {
if (i >= count1 && j >= count2) return 0;
if (i >= count1 && j < count2) return -1;
if (i < count1 && j >= count2) return +1;
utf32_t a;
if (i + 1 >= count1 || !is_surrogate_pair(&str1[i])) {
a = static_cast<utf16_t>(str1[i]);
i++;
}
else {
a = surrogate_pair_to_ucs4(&str1[i]);
i += 2;
}
utf32_t b;
if (j + 1 >= count2 || !is_surrogate_pair(&str2[j])) {
b = static_cast<utf16_t>(str2[j]);
j++;
}
else {
b = surrogate_pair_to_ucs4(&str2[j]);
j += 2;
}
if (a < b) return -1;
if (a > b) return +1;
}
}
///
/// Binary compare two strings
///
/// \param[in] str1 String 1
/// \param[in] count1 String 1 code unit count limit
/// \param[in] str2 String 2
/// \param[in] count2 String 2 code unit count limit
///
/// \return Negative if str1<str2; positive if str1>str2; zero if str1==str2
///
inline int strncmp(
_In_reads_or_z_opt_(count1) const char16_t* str1, _In_ size_t count1,
_In_reads_or_z_opt_(count2) const char16_t* str2, _In_ size_t count2)
{
return strncmp(
reinterpret_cast<const utf16_t*>(str1), count1,
reinterpret_cast<const utf16_t*>(str2), count2);
}
///
/// Binary compare two strings
///
/// \param[in] str1 String 1
/// \param[in] str2 String 2
///
/// \return Negative if str1<str2; positive if str1>str2; zero if str1==str2
///
template <size_t N1, size_t N2>
int strncmp(
_In_ const utf16_t(&str1)[N1],
_In_ const utf16_t(&str2)[N2])
{
return strncmp(str1, N1, str2, N2);
}
///
/// Binary compare two strings
///
/// \param[in] str1 String 1
/// \param[in] str2 String 2
///
/// \return Negative if str1<str2; positive if str1>str2; zero if str1==str2
///
template <size_t N1, size_t N2>
int strncmp(
_In_ const char16_t(&str1)[N1],
_In_ const char16_t(&str2)[N2])
{
return strncmp(
reinterpret_cast<const utf16_t*>(str1), N1,
reinterpret_cast<const utf16_t*>(str2), N2);
}
///
/// Binary compare two strings in reverse direction
///