ClickHouse/src/Common/StringSearcher.h
2020-04-30 16:25:17 +03:00

854 lines
29 KiB
C++

#pragma once
#include <Common/Exception.h>
#include <Common/StringUtils/StringUtils.h>
#include <Common/UTF8Helpers.h>
#include <Core/Defines.h>
#include <ext/range.h>
#include <Poco/Unicode.h>
#include <stdint.h>
#include <string.h>
#ifdef __SSE2__
#include <emmintrin.h>
#endif
#ifdef __SSE4_1__
#include <smmintrin.h>
#endif
namespace DB
{
namespace ErrorCodes
{
extern const int UNSUPPORTED_PARAMETER;
extern const int BAD_ARGUMENTS;
}
/** Variants for searching a substring in a string.
* In most cases, performance is less than Volnitsky (see Volnitsky.h).
*/
struct StringSearcherBase
{
#ifdef __SSE2__
static constexpr auto n = sizeof(__m128i);
const int page_size = getpagesize();
bool pageSafe(const void * const ptr) const
{
return ((page_size - 1) & reinterpret_cast<std::uintptr_t>(ptr)) <= page_size - n;
}
#endif
};
/// Performs case-sensitive and case-insensitive search of UTF-8 strings
template <bool CaseSensitive, bool ASCII> class StringSearcher;
/// Case-insensitive UTF-8 searcher
template <>
class StringSearcher<false, false> : private StringSearcherBase
{
private:
using UTF8SequenceBuffer = uint8_t[6];
/// substring to be searched for
const uint8_t * const needle;
const size_t needle_size;
const uint8_t * const needle_end = needle + needle_size;
/// lower and uppercase variants of the first octet of the first character in `needle`
bool first_needle_symbol_is_ascii{};
uint8_t l{};
uint8_t u{};
#ifdef __SSE4_1__
/// vectors filled with `l` and `u`, for determining leftmost position of the first symbol
__m128i patl;
__m128i patu;
/// lower and uppercase vectors of first 16 characters of `needle`
__m128i cachel = _mm_setzero_si128();
__m128i cacheu = _mm_setzero_si128();
int cachemask{};
size_t cache_valid_len{};
size_t cache_actual_len{};
#endif
public:
template <typename CharT, typename = std::enable_if_t<sizeof(CharT) == 1>>
StringSearcher(const CharT * needle_, const size_t needle_size_)
: needle{reinterpret_cast<const uint8_t *>(needle_)}, needle_size{needle_size_}
{
if (0 == needle_size)
return;
UTF8SequenceBuffer l_seq;
UTF8SequenceBuffer u_seq;
if (*needle < 0x80u)
{
first_needle_symbol_is_ascii = true;
l = std::tolower(*needle);
u = std::toupper(*needle);
}
else
{
const auto first_u32 = UTF8::convert(needle);
const auto first_l_u32 = Poco::Unicode::toLower(first_u32);
const auto first_u_u32 = Poco::Unicode::toUpper(first_u32);
/// lower and uppercase variants of the first octet of the first character in `needle`
UTF8::convert(first_l_u32, l_seq, sizeof(l_seq));
l = l_seq[0];
UTF8::convert(first_u_u32, u_seq, sizeof(u_seq));
u = u_seq[0];
}
#ifdef __SSE4_1__
/// for detecting leftmost position of the first symbol
patl = _mm_set1_epi8(l);
patu = _mm_set1_epi8(u);
/// lower and uppercase vectors of first 16 octets of `needle`
auto needle_pos = needle;
for (size_t i = 0; i < n;)
{
if (needle_pos == needle_end)
{
cachel = _mm_srli_si128(cachel, 1);
cacheu = _mm_srli_si128(cacheu, 1);
++i;
continue;
}
const auto src_len = UTF8::seqLength(*needle_pos);
const auto c_u32 = UTF8::convert(needle_pos);
const auto c_l_u32 = Poco::Unicode::toLower(c_u32);
const auto c_u_u32 = Poco::Unicode::toUpper(c_u32);
const auto dst_l_len = static_cast<uint8_t>(UTF8::convert(c_l_u32, l_seq, sizeof(l_seq)));
const auto dst_u_len = static_cast<uint8_t>(UTF8::convert(c_u_u32, u_seq, sizeof(u_seq)));
/// @note Unicode standard states it is a rare but possible occasion
if (!(dst_l_len == dst_u_len && dst_u_len == src_len))
throw Exception{"UTF8 sequences with different lowercase and uppercase lengths are not supported", ErrorCodes::UNSUPPORTED_PARAMETER};
cache_actual_len += src_len;
if (cache_actual_len < n)
cache_valid_len += src_len;
for (size_t j = 0; j < src_len && i < n; ++j, ++i)
{
cachel = _mm_srli_si128(cachel, 1);
cacheu = _mm_srli_si128(cacheu, 1);
if (needle_pos != needle_end)
{
cachel = _mm_insert_epi8(cachel, l_seq[j], n - 1);
cacheu = _mm_insert_epi8(cacheu, u_seq[j], n - 1);
cachemask |= 1 << i;
++needle_pos;
}
}
}
#endif
}
template <typename CharT, typename = std::enable_if_t<sizeof(CharT) == 1>>
ALWAYS_INLINE bool compare(const CharT * /*haystack*/, const CharT * /*haystack_end*/, const CharT * pos) const
{
#ifdef __SSE4_1__
if (pageSafe(pos))
{
const auto v_haystack = _mm_loadu_si128(reinterpret_cast<const __m128i *>(pos));
const auto v_against_l = _mm_cmpeq_epi8(v_haystack, cachel);
const auto v_against_u = _mm_cmpeq_epi8(v_haystack, cacheu);
const auto v_against_l_or_u = _mm_or_si128(v_against_l, v_against_u);
const auto mask = _mm_movemask_epi8(v_against_l_or_u);
if (0xffff == cachemask)
{
if (mask == cachemask)
{
pos += cache_valid_len;
auto needle_pos = needle + cache_valid_len;
while (needle_pos < needle_end &&
Poco::Unicode::toLower(UTF8::convert(pos)) ==
Poco::Unicode::toLower(UTF8::convert(needle_pos)))
{
/// @note assuming sequences for lowercase and uppercase have exact same length
const auto len = UTF8::seqLength(*pos);
pos += len;
needle_pos += len;
}
if (needle_pos == needle_end)
return true;
}
}
else if ((mask & cachemask) == cachemask)
return true;
return false;
}
#endif
if (*pos == l || *pos == u)
{
pos += first_needle_symbol_is_ascii;
auto needle_pos = needle + first_needle_symbol_is_ascii;
while (needle_pos < needle_end &&
Poco::Unicode::toLower(UTF8::convert(pos)) ==
Poco::Unicode::toLower(UTF8::convert(needle_pos)))
{
const auto len = UTF8::seqLength(*pos);
pos += len;
needle_pos += len;
}
if (needle_pos == needle_end)
return true;
}
return false;
}
/** Returns haystack_end if not found.
*/
template <typename CharT, typename = std::enable_if_t<sizeof(CharT) == 1>>
const CharT * search(const CharT * haystack, const CharT * const haystack_end) const
{
if (0 == needle_size)
return haystack;
while (haystack < haystack_end)
{
#ifdef __SSE4_1__
if (haystack + n <= haystack_end && pageSafe(haystack))
{
const auto v_haystack = _mm_loadu_si128(reinterpret_cast<const __m128i *>(haystack));
const auto v_against_l = _mm_cmpeq_epi8(v_haystack, patl);
const auto v_against_u = _mm_cmpeq_epi8(v_haystack, patu);
const auto v_against_l_or_u = _mm_or_si128(v_against_l, v_against_u);
const auto mask = _mm_movemask_epi8(v_against_l_or_u);
if (mask == 0)
{
haystack += n;
UTF8::syncForward(haystack, haystack_end);
continue;
}
const auto offset = __builtin_ctz(mask);
haystack += offset;
if (haystack < haystack_end && haystack + n <= haystack_end && pageSafe(haystack))
{
const auto v_haystack_offset = _mm_loadu_si128(reinterpret_cast<const __m128i *>(haystack));
const auto v_against_l_offset = _mm_cmpeq_epi8(v_haystack_offset, cachel);
const auto v_against_u_offset = _mm_cmpeq_epi8(v_haystack_offset, cacheu);
const auto v_against_l_or_u_offset = _mm_or_si128(v_against_l_offset, v_against_u_offset);
const auto mask_offset = _mm_movemask_epi8(v_against_l_or_u_offset);
if (0xffff == cachemask)
{
if (mask_offset == cachemask)
{
auto haystack_pos = haystack + cache_valid_len;
auto needle_pos = needle + cache_valid_len;
while (haystack_pos < haystack_end && needle_pos < needle_end &&
Poco::Unicode::toLower(UTF8::convert(haystack_pos)) ==
Poco::Unicode::toLower(UTF8::convert(needle_pos)))
{
/// @note assuming sequences for lowercase and uppercase have exact same length
const auto len = UTF8::seqLength(*haystack_pos);
haystack_pos += len;
needle_pos += len;
}
if (needle_pos == needle_end)
return haystack;
}
}
else if ((mask_offset & cachemask) == cachemask)
return haystack;
/// first octet was ok, but not the first 16, move to start of next sequence and reapply
haystack += UTF8::seqLength(*haystack);
continue;
}
}
#endif
if (haystack == haystack_end)
return haystack_end;
if (*haystack == l || *haystack == u)
{
auto haystack_pos = haystack + first_needle_symbol_is_ascii;
auto needle_pos = needle + first_needle_symbol_is_ascii;
while (haystack_pos < haystack_end && needle_pos < needle_end &&
Poco::Unicode::toLower(UTF8::convert(haystack_pos)) ==
Poco::Unicode::toLower(UTF8::convert(needle_pos)))
{
const auto len = UTF8::seqLength(*haystack_pos);
haystack_pos += len;
needle_pos += len;
}
if (needle_pos == needle_end)
return haystack;
}
/// advance to the start of the next sequence
haystack += UTF8::seqLength(*haystack);
}
return haystack_end;
}
template <typename CharT, typename = std::enable_if_t<sizeof(CharT) == 1>>
const CharT * search(const CharT * haystack, const size_t haystack_size) const
{
return search(haystack, haystack + haystack_size);
}
};
/// Case-insensitive ASCII searcher
template <>
class StringSearcher<false, true> : private StringSearcherBase
{
private:
/// string to be searched for
const uint8_t * const needle;
const uint8_t * const needle_end;
/// lower and uppercase variants of the first character in `needle`
uint8_t l{};
uint8_t u{};
#ifdef __SSE4_1__
/// vectors filled with `l` and `u`, for determining leftmost position of the first symbol
__m128i patl, patu;
/// lower and uppercase vectors of first 16 characters of `needle`
__m128i cachel = _mm_setzero_si128(), cacheu = _mm_setzero_si128();
int cachemask{};
#endif
public:
template <typename CharT, typename = std::enable_if_t<sizeof(CharT) == 1>>
StringSearcher(const CharT * needle_, const size_t needle_size)
: needle{reinterpret_cast<const uint8_t *>(needle_)}, needle_end{needle + needle_size}
{
if (0 == needle_size)
return;
l = static_cast<uint8_t>(std::tolower(*needle));
u = static_cast<uint8_t>(std::toupper(*needle));
#ifdef __SSE4_1__
patl = _mm_set1_epi8(l);
patu = _mm_set1_epi8(u);
auto needle_pos = needle;
for (const auto i : ext::range(0, n))
{
cachel = _mm_srli_si128(cachel, 1);
cacheu = _mm_srli_si128(cacheu, 1);
if (needle_pos != needle_end)
{
cachel = _mm_insert_epi8(cachel, std::tolower(*needle_pos), n - 1);
cacheu = _mm_insert_epi8(cacheu, std::toupper(*needle_pos), n - 1);
cachemask |= 1 << i;
++needle_pos;
}
}
#endif
}
template <typename CharT, typename = std::enable_if_t<sizeof(CharT) == 1>>
ALWAYS_INLINE bool compare(const CharT * /*haystack*/, const CharT * /*haystack_end*/, const CharT * pos) const
{
#ifdef __SSE4_1__
if (pageSafe(pos))
{
const auto v_haystack = _mm_loadu_si128(reinterpret_cast<const __m128i *>(pos));
const auto v_against_l = _mm_cmpeq_epi8(v_haystack, cachel);
const auto v_against_u = _mm_cmpeq_epi8(v_haystack, cacheu);
const auto v_against_l_or_u = _mm_or_si128(v_against_l, v_against_u);
const auto mask = _mm_movemask_epi8(v_against_l_or_u);
if (0xffff == cachemask)
{
if (mask == cachemask)
{
pos += n;
auto needle_pos = needle + n;
while (needle_pos < needle_end && std::tolower(*pos) == std::tolower(*needle_pos))
{
++pos;
++needle_pos;
}
if (needle_pos == needle_end)
return true;
}
}
else if ((mask & cachemask) == cachemask)
return true;
return false;
}
#endif
if (*pos == l || *pos == u)
{
++pos;
auto needle_pos = needle + 1;
while (needle_pos < needle_end && std::tolower(*pos) == std::tolower(*needle_pos))
{
++pos;
++needle_pos;
}
if (needle_pos == needle_end)
return true;
}
return false;
}
template <typename CharT, typename = std::enable_if_t<sizeof(CharT) == 1>>
const CharT * search(const CharT * haystack, const CharT * const haystack_end) const
{
if (needle == needle_end)
return haystack;
while (haystack < haystack_end)
{
#ifdef __SSE4_1__
if (haystack + n <= haystack_end && pageSafe(haystack))
{
const auto v_haystack = _mm_loadu_si128(reinterpret_cast<const __m128i *>(haystack));
const auto v_against_l = _mm_cmpeq_epi8(v_haystack, patl);
const auto v_against_u = _mm_cmpeq_epi8(v_haystack, patu);
const auto v_against_l_or_u = _mm_or_si128(v_against_l, v_against_u);
const auto mask = _mm_movemask_epi8(v_against_l_or_u);
if (mask == 0)
{
haystack += n;
continue;
}
const auto offset = __builtin_ctz(mask);
haystack += offset;
if (haystack < haystack_end && haystack + n <= haystack_end && pageSafe(haystack))
{
const auto v_haystack_offset = _mm_loadu_si128(reinterpret_cast<const __m128i *>(haystack));
const auto v_against_l_offset = _mm_cmpeq_epi8(v_haystack_offset, cachel);
const auto v_against_u_offset = _mm_cmpeq_epi8(v_haystack_offset, cacheu);
const auto v_against_l_or_u_offset = _mm_or_si128(v_against_l_offset, v_against_u_offset);
const auto mask_offset = _mm_movemask_epi8(v_against_l_or_u_offset);
if (0xffff == cachemask)
{
if (mask_offset == cachemask)
{
auto haystack_pos = haystack + n;
auto needle_pos = needle + n;
while (haystack_pos < haystack_end && needle_pos < needle_end &&
std::tolower(*haystack_pos) == std::tolower(*needle_pos))
{
++haystack_pos;
++needle_pos;
}
if (needle_pos == needle_end)
return haystack;
}
}
else if ((mask_offset & cachemask) == cachemask)
return haystack;
++haystack;
continue;
}
}
#endif
if (haystack == haystack_end)
return haystack_end;
if (*haystack == l || *haystack == u)
{
auto haystack_pos = haystack + 1;
auto needle_pos = needle + 1;
while (haystack_pos < haystack_end && needle_pos < needle_end &&
std::tolower(*haystack_pos) == std::tolower(*needle_pos))
{
++haystack_pos;
++needle_pos;
}
if (needle_pos == needle_end)
return haystack;
}
++haystack;
}
return haystack_end;
}
template <typename CharT, typename = std::enable_if_t<sizeof(CharT) == 1>>
const CharT * search(const CharT * haystack, const size_t haystack_size) const
{
return search(haystack, haystack + haystack_size);
}
};
/// Case-sensitive searcher (both ASCII and UTF-8)
template <bool ASCII>
class StringSearcher<true, ASCII> : private StringSearcherBase
{
private:
/// string to be searched for
const uint8_t * const needle;
const uint8_t * const needle_end;
/// first character in `needle`
uint8_t first{};
#ifdef __SSE4_1__
/// vector filled `first` for determining leftmost position of the first symbol
__m128i pattern;
/// vector of first 16 characters of `needle`
__m128i cache = _mm_setzero_si128();
int cachemask{};
#endif
public:
template <typename CharT, typename = std::enable_if_t<sizeof(CharT) == 1>>
StringSearcher(const CharT * needle_, const size_t needle_size)
: needle{reinterpret_cast<const uint8_t *>(needle_)}, needle_end{needle + needle_size}
{
if (0 == needle_size)
return;
first = *needle;
#ifdef __SSE4_1__
pattern = _mm_set1_epi8(first);
auto needle_pos = needle;
for (const auto i : ext::range(0, n))
{
cache = _mm_srli_si128(cache, 1);
if (needle_pos != needle_end)
{
cache = _mm_insert_epi8(cache, *needle_pos, n - 1);
cachemask |= 1 << i;
++needle_pos;
}
}
#endif
}
template <typename CharT, typename = std::enable_if_t<sizeof(CharT) == 1>>
ALWAYS_INLINE bool compare(const CharT * /*haystack*/, const CharT * /*haystack_end*/, const CharT * pos) const
{
#ifdef __SSE4_1__
if (pageSafe(pos))
{
const auto v_haystack = _mm_loadu_si128(reinterpret_cast<const __m128i *>(pos));
const auto v_against_cache = _mm_cmpeq_epi8(v_haystack, cache);
const auto mask = _mm_movemask_epi8(v_against_cache);
if (0xffff == cachemask)
{
if (mask == cachemask)
{
pos += n;
auto needle_pos = needle + n;
while (needle_pos < needle_end && *pos == *needle_pos)
++pos, ++needle_pos;
if (needle_pos == needle_end)
return true;
}
}
else if ((mask & cachemask) == cachemask)
return true;
return false;
}
#endif
if (*pos == first)
{
++pos;
auto needle_pos = needle + 1;
while (needle_pos < needle_end && *pos == *needle_pos)
++pos, ++needle_pos;
if (needle_pos == needle_end)
return true;
}
return false;
}
template <typename CharT, typename = std::enable_if_t<sizeof(CharT) == 1>>
const CharT * search(const CharT * haystack, const CharT * const haystack_end) const
{
if (needle == needle_end)
return haystack;
while (haystack < haystack_end)
{
#ifdef __SSE4_1__
if (haystack + n <= haystack_end && pageSafe(haystack))
{
/// find first character
const auto v_haystack = _mm_loadu_si128(reinterpret_cast<const __m128i *>(haystack));
const auto v_against_pattern = _mm_cmpeq_epi8(v_haystack, pattern);
const auto mask = _mm_movemask_epi8(v_against_pattern);
/// first character not present in 16 octets starting at `haystack`
if (mask == 0)
{
haystack += n;
continue;
}
const auto offset = __builtin_ctz(mask);
haystack += offset;
if (haystack < haystack_end && haystack + n <= haystack_end && pageSafe(haystack))
{
/// check for first 16 octets
const auto v_haystack_offset = _mm_loadu_si128(reinterpret_cast<const __m128i *>(haystack));
const auto v_against_cache = _mm_cmpeq_epi8(v_haystack_offset, cache);
const auto mask_offset = _mm_movemask_epi8(v_against_cache);
if (0xffff == cachemask)
{
if (mask_offset == cachemask)
{
auto haystack_pos = haystack + n;
auto needle_pos = needle + n;
while (haystack_pos < haystack_end && needle_pos < needle_end &&
*haystack_pos == *needle_pos)
++haystack_pos, ++needle_pos;
if (needle_pos == needle_end)
return haystack;
}
}
else if ((mask_offset & cachemask) == cachemask)
return haystack;
++haystack;
continue;
}
}
#endif
if (haystack == haystack_end)
return haystack_end;
if (*haystack == first)
{
auto haystack_pos = haystack + 1;
auto needle_pos = needle + 1;
while (haystack_pos < haystack_end && needle_pos < needle_end &&
*haystack_pos == *needle_pos)
++haystack_pos, ++needle_pos;
if (needle_pos == needle_end)
return haystack;
}
++haystack;
}
return haystack_end;
}
template <typename CharT, typename = std::enable_if_t<sizeof(CharT) == 1>>
const CharT * search(const CharT * haystack, const size_t haystack_size) const
{
return search(haystack, haystack + haystack_size);
}
};
// Searches for needle surrounded by token-separators.
// Separators are anything inside ASCII (0-128) and not alphanum.
// Any value outside of basic ASCII (>=128) is considered a non-separator symbol, hence UTF-8 strings
// should work just fine. But any Unicode whitespace is not considered a token separtor.
template <typename StringSearcher>
class TokenSearcher
{
StringSearcher searcher;
size_t needle_size;
public:
template <typename CharT, typename = std::enable_if_t<sizeof(CharT) == 1>>
TokenSearcher(const CharT * needle_, const size_t needle_size_)
: searcher{needle_, needle_size_},
needle_size(needle_size_)
{
if (std::any_of(needle_, needle_ + needle_size_, isTokenSeparator))
{
throw Exception{"Needle must not contain whitespace or separator characters", ErrorCodes::BAD_ARGUMENTS};
}
}
template <typename CharT, typename = std::enable_if_t<sizeof(CharT) == 1>>
ALWAYS_INLINE bool compare(const CharT * haystack, const CharT * haystack_end, const CharT * pos) const
{
// use searcher only if pos is in the beginning of token and pos + searcher.needle_size is end of token.
if (isToken(haystack, haystack_end, pos))
return searcher.compare(haystack, haystack_end, pos);
return false;
}
template <typename CharT, typename = std::enable_if_t<sizeof(CharT) == 1>>
const CharT * search(const CharT * haystack, const CharT * const haystack_end) const
{
// use searcher.search(), then verify that returned value is a token
// if it is not, skip it and re-run
const auto * pos = haystack;
while (pos < haystack_end)
{
pos = searcher.search(pos, haystack_end);
if (pos == haystack_end || isToken(haystack, haystack_end, pos))
return pos;
// assuming that heendle does not contain any token separators.
pos += needle_size;
}
return haystack_end;
}
template <typename CharT, typename = std::enable_if_t<sizeof(CharT) == 1>>
const CharT * search(const CharT * haystack, const size_t haystack_size) const
{
return search(haystack, haystack + haystack_size);
}
template <typename CharT, typename = std::enable_if_t<sizeof(CharT) == 1>>
ALWAYS_INLINE bool isToken(const CharT * haystack, const CharT * const haystack_end, const CharT* p) const
{
return (p == haystack || isTokenSeparator(*(p - 1)))
&& (p + needle_size >= haystack_end || isTokenSeparator(*(p + needle_size)));
}
ALWAYS_INLINE static bool isTokenSeparator(const uint8_t c)
{
if (isAlphaNumericASCII(c) || !isASCII(c))
return false;
return true;
}
};
using ASCIICaseSensitiveStringSearcher = StringSearcher<true, true>;
using ASCIICaseInsensitiveStringSearcher = StringSearcher<false, true>;
using UTF8CaseSensitiveStringSearcher = StringSearcher<true, false>;
using UTF8CaseInsensitiveStringSearcher = StringSearcher<false, false>;
using ASCIICaseSensitiveTokenSearcher = TokenSearcher<ASCIICaseSensitiveStringSearcher>;
using ASCIICaseInsensitiveTokenSearcher = TokenSearcher<ASCIICaseInsensitiveStringSearcher>;
/** Uses functions from libc.
* It makes sense to use only with short haystacks when cheap initialization is required.
* There is no option for case-insensitive search for UTF-8 strings.
* It is required that strings are zero-terminated.
*/
struct LibCASCIICaseSensitiveStringSearcher
{
const char * const needle;
template <typename CharT, typename = std::enable_if_t<sizeof(CharT) == 1>>
LibCASCIICaseSensitiveStringSearcher(const CharT * const needle_, const size_t /* needle_size */)
: needle(reinterpret_cast<const char *>(needle_)) {}
template <typename CharT, typename = std::enable_if_t<sizeof(CharT) == 1>>
const CharT * search(const CharT * haystack, const CharT * const haystack_end) const
{
auto res = strstr(reinterpret_cast<const char *>(haystack), reinterpret_cast<const char *>(needle));
if (!res)
return haystack_end;
return reinterpret_cast<const CharT *>(res);
}
template <typename CharT, typename = std::enable_if_t<sizeof(CharT) == 1>>
const CharT * search(const CharT * haystack, const size_t haystack_size) const
{
return search(haystack, haystack + haystack_size);
}
};
struct LibCASCIICaseInsensitiveStringSearcher
{
const char * const needle;
template <typename CharT, typename = std::enable_if_t<sizeof(CharT) == 1>>
LibCASCIICaseInsensitiveStringSearcher(const CharT * const needle_, const size_t /* needle_size */)
: needle(reinterpret_cast<const char *>(needle_)) {}
template <typename CharT, typename = std::enable_if_t<sizeof(CharT) == 1>>
const CharT * search(const CharT * haystack, const CharT * const haystack_end) const
{
auto res = strcasestr(reinterpret_cast<const char *>(haystack), reinterpret_cast<const char *>(needle));
if (!res)
return haystack_end;
return reinterpret_cast<const CharT *>(res);
}
template <typename CharT, typename = std::enable_if_t<sizeof(CharT) == 1>>
const CharT * search(const CharT * haystack, const size_t haystack_size) const
{
return search(haystack, haystack + haystack_size);
}
};
}