We don't need to use an istringstream to convert a hex digit to its
numerical value.
libstdc++-v3/ChangeLog:
* include/bits/regex.tcc (regex_traits::value): Implement
without using istringstream.
* include/std/regex: Do not include <sstream>.
---
Tested x86_64-linux.
This changes what we do for radix != 8 && radix != 16 but that's fine,
because it's undefined to use an arbitrary radix anyway. The standard
says:
Preconditions: The value of radix is 8, 10, or 16.
libstdc++-v3/include/bits/regex.tcc | 49 ++++++++++++++++++++++++-----
libstdc++-v3/include/std/regex | 1 -
2 files changed, 41 insertions(+), 9 deletions(-)
diff --git a/libstdc++-v3/include/bits/regex.tcc
b/libstdc++-v3/include/bits/regex.tcc
index b94fe4490f7c..a0edf272717e 100644
--- a/libstdc++-v3/include/bits/regex.tcc
+++ b/libstdc++-v3/include/bits/regex.tcc
@@ -331,20 +331,53 @@ namespace __detail
&& __c == __fctyp.widen('_'));
}
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wc++17-extensions" // if constexpr
template<typename _Ch_type>
int
regex_traits<_Ch_type>::
value(_Ch_type __ch, int __radix) const
{
- std::basic_istringstream<char_type> __is(string_type(1, __ch));
- long __v;
- if (__radix == 8)
- __is >> std::oct;
- else if (__radix == 16)
- __is >> std::hex;
- __is >> __v;
- return __is.fail() ? -1 : __v;
+ if constexpr (sizeof(_Ch_type) > 1)
+ {
+ const auto& __ctyp = std::use_facet<ctype<_Ch_type>>(_M_locale);
+ const char __c = __ctyp.narrow(__ch, '\0');
+ return regex_traits<char>{}.value(__c, __radix);
+ }
+ else
+ {
+ const char __c = static_cast<char>(__ch);
+ const char __max_digit = __radix == 8 ? '7' : '9';
+ if ('0' <= __ch && __ch <= __max_digit)
+ return __ch - '0';
+ if (__radix < 16)
+ return -1;
+ switch (__ch)
+ {
+ case 'a':
+ case 'A':
+ return 10;
+ case 'b':
+ case 'B':
+ return 11;
+ case 'c':
+ case 'C':
+ return 12;
+ case 'd':
+ case 'D':
+ return 13;
+ case 'e':
+ case 'E':
+ return 14;
+ case 'f':
+ case 'F':
+ return 15;
+ default:
+ return -1;
+ }
+ }
}
+#pragma GCC diagnostic pop
template<typename _Bi_iter, typename _Alloc>
template<typename _Out_iter>
diff --git a/libstdc++-v3/include/std/regex b/libstdc++-v3/include/std/regex
index 022306621cba..9121d267a793 100644
--- a/libstdc++-v3/include/std/regex
+++ b/libstdc++-v3/include/std/regex
@@ -41,7 +41,6 @@
#include <bitset>
#include <locale>
-#include <sstream>
#include <stack>
#include <stdexcept>
#include <string>
--
2.51.0
