Second part of P0482 - char8_t. Reviewed as https://reviews.llvm.org/D55308

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@348828 91177308-0d34-0410-b5e6-96231b3b80d8
2018-12-11 04:35:44 +00:00
parent 21a8669ade
commit 96484477d1
91 changed files with 1152 additions and 103 deletions
--- a/include/__string
+++ b/include/__string
@@ -47,6 +47,7 @@ struct char_traits

 template <> struct char_traits<char>;
 template <> struct char_traits<wchar_t>;
+template <> struct char_traits<char8_t>;  // c++20

 }  // std

@@ -389,6 +390,102 @@ char_traits<wchar_t>::find(const char_type* __s, size_t __n, const char_type& __
 }


+#ifndef _LIBCPP_NO_HAS_CHAR8_T
+
+template <>
+struct _LIBCPP_TEMPLATE_VIS char_traits<char8_t>
+{
+    typedef char8_t        char_type;
+    typedef unsigned int   int_type;
+    typedef streamoff      off_type;
+    typedef u8streampos    pos_type;
+    typedef mbstate_t      state_type;
+
+    static inline constexpr void assign(char_type& __c1, const char_type& __c2) noexcept
+        {__c1 = __c2;}
+    static inline constexpr bool eq(char_type __c1, char_type __c2) noexcept
+        {return __c1 == __c2;}
+    static inline constexpr bool lt(char_type __c1, char_type __c2) noexcept
+        {return __c1 < __c2;}
+
+    static constexpr
+    int              compare(const char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT;
+
+    static constexpr
+    size_t           length(const char_type* __s) _NOEXCEPT;
+ 
+    _LIBCPP_INLINE_VISIBILITY static constexpr
+    const char_type* find(const char_type* __s, size_t __n, const char_type& __a) _NOEXCEPT;
+ 
+    static char_type*       move(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT
+        {return __n == 0 ? __s1 : (char_type*) memmove(__s1, __s2, __n);}
+ 
+    static char_type*       copy(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT
+       {
+            _LIBCPP_ASSERT(__s2 < __s1 || __s2 >= __s1+__n, "char_traits::copy overlapped range");
+            return __n == 0 ? __s1 : (char_type*)memcpy(__s1, __s2, __n);
+       }
+ 
+    static char_type*       assign(char_type* __s, size_t __n, char_type __a) _NOEXCEPT
+        {return __n == 0 ? __s : (char_type*)memset(__s, to_int_type(__a), __n);}
+
+    static inline constexpr int_type  not_eof(int_type __c) noexcept
+        {return eq_int_type(__c, eof()) ? ~eof() : __c;}
+    static inline constexpr char_type to_char_type(int_type __c) noexcept
+        {return char_type(__c);}
+    static inline constexpr int_type to_int_type(char_type __c) noexcept
+        {return int_type(__c);}
+    static inline constexpr bool eq_int_type(int_type __c1, int_type __c2) noexcept
+        {return __c1 == __c2;}
+    static inline constexpr int_type eof() noexcept
+        {return int_type(EOF);}
+};
+
+// TODO use '__builtin_strlen' if it ever supports char8_t ??
+inline constexpr
+size_t
+char_traits<char8_t>::length(const char_type* __s) _NOEXCEPT
+{
+    size_t __len = 0;
+    for (; !eq(*__s, char_type(0)); ++__s)
+        ++__len;
+    return __len;
+}
+
+inline constexpr
+int
+char_traits<char8_t>::compare(const char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT
+{
+#if __has_feature(cxx_constexpr_string_builtins)
+    return __builtin_memcmp(__s1, __s2, __n);
+#else
+    for (; __n; --__n, ++__s1, ++__s2)
+    {
+        if (lt(*__s1, *__s2))
+            return -1;
+        if (lt(*__s2, *__s1))
+            return 1;
+    }
+    return 0;
+#endif
+}
+
+// TODO use '__builtin_char_memchr' if it ever supports char8_t ??
+inline constexpr
+const char8_t*
+char_traits<char8_t>::find(const char_type* __s, size_t __n, const char_type& __a) _NOEXCEPT
+{
+    for (; __n; --__n)
+    {
+        if (eq(*__s, __a))
+            return __s;
+        ++__s;
+    }
+    return 0;
+}
+
+#endif // #_LIBCPP_NO_HAS_CHAR8_T
+
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS

 template <>