1 files changed, 45 insertions, 38 deletions

diff --git a/zen/string_traits.h b/zen/string_traits.h
index 805db46d..8187126d 100755
--- a/zen/string_traits.h
+++ b/zen/string_traits.h
@@ -8,20 +8,20 @@
 #define STRING_TRAITS_H_813274321443234
 
 #include <cstring> //strlen
-#include "type_tools.h"
+#include "type_traits.h"
 
 
 //uniform access to string-like types, both classes and character arrays
 namespace zen
 {
 /*
-IsStringLike<>::value:
-    IsStringLike<const wchar_t*>::value; //equals "true"
-    IsStringLike<const int*>    ::value; //equals "false"
+IsStringLikeV<>:
+    IsStringLikeV<const wchar_t*> //equals "true"
+    IsStringLikeV<const int*>     //equals "false"
 
-GetCharType<>::Type:
-    GetCharType<std::wstring>::Type  //equals wchar_t
-    GetCharType<wchar_t[5]>  ::Type  //equals wchar_t
+GetCharTypeT<>:
+    GetCharTypeT<std::wstring> //equals wchar_t
+    GetCharTypeT<wchar_t[5]>   //equals wchar_t
 
 strLength():
     strLength(str);   //equals str.length()
@@ -34,6 +34,7 @@ strBegin():         -> not null-terminated! -> may be nullptr if length is 0!
     strBegin(array); //returns array
 */
 
+
 //reference a sub-string for consumption by zen string_tools
 template <class Char>
 class StringRef
@@ -79,15 +80,14 @@ public:
 };
 
 
-template <class S, bool isStringClass>  struct GetCharTypeImpl : ResultType<NullType> {};
+template <class S, bool isStringClass>  struct GetCharTypeImpl { using Type = void; };
 
 template <class S>
-struct GetCharTypeImpl<S, true> :
-    ResultType<
-    typename SelectIf<HasConversion<S, wchar_t>::value, wchar_t,
-    typename SelectIf<HasConversion<S, char   >::value, char, NullType>::Type
-    >::Type>
+struct GetCharTypeImpl<S, true>
 {
+    using Type = std::conditional_t<HasConversion<S, wchar_t>::value, wchar_t,
+          /**/   std::conditional_t<HasConversion<S, char   >::value, char, void>>;
+
     //using Type = typename S::value_type;
     /*DON'T use S::value_type:
         1. support Glib::ustring: value_type is "unsigned int" but c_str() returns "const char*"
@@ -96,13 +96,13 @@ struct GetCharTypeImpl<S, true> :
     */
 };
 
-template <> struct GetCharTypeImpl<char,    false> : ResultType<char   > {};
-template <> struct GetCharTypeImpl<wchar_t, false> : ResultType<wchar_t> {};
+template <> struct GetCharTypeImpl<char,    false> { using Type = char; };
+template <> struct GetCharTypeImpl<wchar_t, false> { using Type = wchar_t; };
 
-template <> struct GetCharTypeImpl<StringRef<char         >, false> : ResultType<char   > {};
-template <> struct GetCharTypeImpl<StringRef<wchar_t      >, false> : ResultType<wchar_t> {};
-template <> struct GetCharTypeImpl<StringRef<const char   >, false> : ResultType<char   > {};
-template <> struct GetCharTypeImpl<StringRef<const wchar_t>, false> : ResultType<wchar_t> {};
+template <> struct GetCharTypeImpl<StringRef<char         >, false> { using Type = char; };
+template <> struct GetCharTypeImpl<StringRef<wchar_t      >, false> { using Type = wchar_t; };
+template <> struct GetCharTypeImpl<StringRef<const char   >, false> { using Type = char; };
+template <> struct GetCharTypeImpl<StringRef<const wchar_t>, false> { using Type = wchar_t; };
 
 
 ZEN_INIT_DETECT_MEMBER_TYPE(value_type);
@@ -112,35 +112,42 @@ ZEN_INIT_DETECT_MEMBER(length); //
 template <class S>
 class StringTraits
 {
-    using NonRefType      = typename RemoveRef    <S           >::Type;
-    using NonConstType    = typename RemoveConst  <NonRefType  >::Type;
-    using NonArrayType    = typename RemoveArray  <NonConstType>::Type;
-    using NonPtrType      = typename RemovePointer<NonArrayType>::Type;
-    using UndecoratedType = typename RemoveConst  <NonPtrType  >::Type ; //handle "const char* const"
+    using CleanType       = std::remove_cv_t<std::remove_reference_t<S>>; //std::remove_cvref requires C++20
+    using NonArrayType    = std::remove_extent_t <CleanType>;
+    using NonPtrType      = std::remove_pointer_t<NonArrayType>;
+    using UndecoratedType = std::remove_cv_t     <NonPtrType>; //handle "const char* const"
 
 public:
     enum
     {
-        isStringClass = HasMemberType_value_type<NonConstType>::value &&
-                        HasMember_c_str         <NonConstType>::value &&
-                        HasMember_length        <NonConstType>::value
+        isStringClass = HasMemberType_value_type<CleanType>::value &&
+                        HasMember_c_str         <CleanType>::value &&
+                        HasMember_length        <CleanType>::value
     };
 
     using CharType = typename GetCharTypeImpl<UndecoratedType, isStringClass>::Type;
 
     enum
     {
-        isStringLike = IsSameType<CharType, char>::value ||
-        IsSameType<CharType, wchar_t>::value
+        isStringLike = std::is_same_v<CharType, char> ||
+        std::is_same_v<CharType, wchar_t>
     };
 };
 }
 
 template <class T>
-struct IsStringLike : StaticBool<impl::StringTraits<T>::isStringLike> {};
+struct IsStringLike : std::bool_constant<impl::StringTraits<T>::isStringLike> {};
 
 template <class T>
-struct GetCharType : ResultType<typename impl::StringTraits<T>::CharType> {};
+struct GetCharType { using Type = typename impl::StringTraits<T>::CharType; };
+
+
+//template alias helpers:
+template<class T>
+constexpr bool IsStringLikeV = IsStringLike<T>::value;
+
+template<class T>
+using GetCharTypeT = typename GetCharType<T>::Type;
 
 
 namespace impl
@@ -154,7 +161,7 @@ inline size_t cStringLength(const wchar_t* str) { return std::wcslen(str); }
 template <class C> inline
 size_t cStringLength(const C* str)
 {
-    static_assert(IsSameType<C, char>::value || IsSameType<C, wchar_t>::value, "");
+    static_assert(std::is_same_v<C, char> || std::is_same_v<C, wchar_t>);
     size_t len = 0;
     while (*str++ != 0)
         ++len;
@@ -162,8 +169,8 @@ size_t cStringLength(const C* str)
 }
 #endif
 
-template <class S, typename = typename EnableIf<StringTraits<S>::isStringClass>::Type> inline
-const typename GetCharType<S>::Type* strBegin(const S& str) //SFINAE: T must be a "string"
+template <class S, typename = std::enable_if_t<StringTraits<S>::isStringClass>> inline
+const GetCharTypeT<S>* strBegin(const S& str) //SFINAE: T must be a "string"
 {
     return str.c_str();
 }
@@ -179,7 +186,7 @@ inline const char*    strBegin(const StringRef<const char   >& ref) { return ref
 inline const wchar_t* strBegin(const StringRef<const wchar_t>& ref) { return ref.data(); }
 
 
-template <class S, typename = typename EnableIf<StringTraits<S>::isStringClass>::Type> inline
+template <class S, typename = std::enable_if_t<StringTraits<S>::isStringClass>> inline
 size_t strLength(const S& str) //SFINAE: T must be a "string"
 {
     return str.length();
@@ -198,9 +205,9 @@ inline size_t strLength(const StringRef<const wchar_t>& ref) { return ref.length
 
 
 template <class S> inline
-auto strBegin(S&& str) -> const typename GetCharType<S>::Type*
+auto strBegin(S&& str) -> const GetCharTypeT<S>*
 {
-    static_assert(IsStringLike<S>::value, "");
+    static_assert(IsStringLikeV<S>);
     return impl::strBegin(std::forward<S>(str));
 }
 
@@ -208,7 +215,7 @@ auto strBegin(S&& str) -> const typename GetCharType<S>::Type*
 template <class S> inline
 size_t strLength(S&& str)
 {
-    static_assert(IsStringLike<S>::value, "");
+    static_assert(IsStringLikeV<S>);
     return impl::strLength(std::forward<S>(str));
 }
 }