1 files changed, 176 insertions, 0 deletions
diff --git a/zen/string_traits.h b/zen/string_traits.h
new file mode 100644
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--- /dev/null
+++ b/zen/string_traits.h
@@ -0,0 +1,176 @@
+// **************************************************************************
+// * This file is part of the zenXML project. It is distributed under the   *
+// * Boost Software License, Version 1.0. See accompanying file             *
+// * LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt.       *
+// * Copyright (C) 2011 ZenJu (zhnmju123 AT gmx.de)                         *
+// **************************************************************************
+
+#ifndef STRING_TRAITS_HEADER_813274321443234
+#define STRING_TRAITS_HEADER_813274321443234
+
+#include "type_tools.h"
+#include "assert_static.h"
+
+
+//uniform access to string-like types: classes and character arrays
+namespace zen
+{
+/*
+strBegin():
+	std::wstring str(L"dummy");
+	char array[] = "dummy";
+	const wchar_t* iter  = strBegin(str);   //returns str.c_str()
+	const char*    iter2 = strBegin(array); //returns array
+
+strLength():
+	strLength(str);   //equals str.size()
+	strLength(array); //equals cStringLength(array)
+
+StringTraits<>::CharType:
+	StringTraits<std::wstring>::CharType  //equals wchar_t
+	StringTraits<wchar_t[5]>  ::CharType  //equals wchar_t
+
+StringTraits<>::isStringLike:
+    StringTraits<const wchar_t*>::isStringLike; //equals "true"
+	StringTraits<const int*>    ::isStringLike; //equals "false"
+
+StringTraits<>::isStringClass:
+	StringTraits<std::wstring>::isStringClass  //equals "true"
+	StringTraits<wchar_t[5]>  ::isStringClass  //equals "false"
+*/
+
+
+
+
+
+
+
+
+
+
+
+
+
+//---------------------- implementation ----------------------
+namespace implementation
+{
+template<typename T>
+class HasValueTypedef
+{
+    typedef char Yes[1];
+    typedef char No [2];
+
+    template <typename U> class HelperTp {};
+
+    //detect presence of a member type called value_type
+    template <class U> static Yes& hasMemberValueType(HelperTp<typename U::value_type>*);
+    template <class U> static  No& hasMemberValueType(...);
+
+public:
+    enum { result = sizeof(hasMemberValueType<T>(NULL)) == sizeof(Yes)
+         };
+};
+
+
+template<typename T, bool isClassType>
+class HasStringMembers
+{
+public:
+    enum { result = false };
+};
+
+template<typename T>
+class HasStringMembers<T, true>
+{
+    typedef char Yes[1];
+    typedef char No [2];
+
+    //detect presence of member functions (without specific restriction on return type, within T or one of it's base classes)
+    template <typename U, U t> class HelperFn {};
+
+    struct Fallback
+    {
+        int c_str;
+        int length;
+    };
+
+    template <class U>
+    struct Helper2 : public U, public Fallback {}; //U must be a class-type!
+
+    //we don't know the exact declaration of the member attribute (may be in base class), but we know what NOT to expect:
+    template <class U> static  No& hasMemberCstr(HelperFn<int Fallback::*, &Helper2<U>::c_str>*);
+    template <class U> static Yes& hasMemberCstr(...);
+
+    template <class U> static  No& hasMemberLength(HelperFn<int Fallback::*, &Helper2<U>::length>*);
+    template <class U> static Yes& hasMemberLength(...);
+public:
+    enum { result = sizeof(hasMemberCstr  <T>(NULL)) == sizeof(Yes) &&
+                    sizeof(hasMemberLength<T>(NULL)) == sizeof(Yes)
+         };
+};
+
+template <class S, bool isStringClass> struct StringTraits2 { typedef EmptyType Result; }; //"StringTraits2": fix some VS bug with namespace and partial template specialization
+
+template <class S> struct StringTraits2<S,       true > { typedef typename S::value_type Result; };
+template <>        struct StringTraits2<char,    false> { typedef char                   Result; };
+template <>        struct StringTraits2<wchar_t, false> { typedef wchar_t                Result; };
+}
+
+
+template <class S>
+struct StringTraits
+{
+private:
+    typedef typename RemoveRef    <S           >::Result NonRefType;
+    typedef typename RemoveConst  <NonRefType  >::Result NonConstType;
+    typedef typename RemoveArray  <NonConstType>::Result NonArrayType;
+    typedef typename RemovePointer<NonArrayType>::Result NonPtrType;
+    typedef typename RemoveConst  <NonPtrType  >::Result UndecoratedType; //handle "const char* const"
+public:
+    enum
+    {
+        isStringClass = implementation::HasStringMembers<NonConstType, implementation::HasValueTypedef<NonConstType>::result>::result
+    };
+
+    typedef typename implementation::StringTraits2<UndecoratedType, isStringClass>::Result CharType;
+
+    enum
+    {
+        isStringLike = IsSameType<CharType, char>::result || IsSameType<CharType, wchar_t>::result
+    };
+};
+
+
+namespace implementation
+{
+template <class C> inline
+size_t cStringLength(const C* str) //strlen()
+{
+    assert_static((IsSameType<C, char>::result || IsSameType<C, wchar_t>::result));
+    size_t len = 0;
+    while (*str++ != 0)
+        ++len;
+    return len;
+}
+}
+
+
+template <class S> inline
+const typename StringTraits<S>::CharType* strBegin(const S& str, typename S::value_type dummy = 0) { return str.c_str(); } //SFINAE: T must be a "string"
+
+template <class Char>
+inline const typename StringTraits<Char>::CharType* strBegin(const Char* str) { return str; }
+inline const char*    strBegin(const char& ch)    { return &ch; }
+inline const wchar_t* strBegin(const wchar_t& ch) { return &ch; }
+
+
+template <class S> inline
+size_t strLength(const S& str, typename S::value_type dummy = 0) { return str.length(); } //SFINAE: T must be a "string"
+
+template <class Char>
+inline size_t strLength(const Char* str) { return implementation::cStringLength(str); }
+inline size_t strLength(char)            { return 1; }
+inline size_t strLength(wchar_t)         { return 1; }
+}
+
+#endif //STRING_TRAITS_HEADER_813274321443234