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// **************************************************************************
// * This file is part of the zenXML project. It is distributed under the *
// * Boost Software License: http://www.boost.org/LICENSE_1_0.txt *
// * Copyright (C) Zenju (zenju AT gmx DOT de) - All Rights Reserved *
// **************************************************************************
#ifndef STRING_TRAITS_HEADER_813274321443234
#define STRING_TRAITS_HEADER_813274321443234
#include "type_tools.h"
#include "assert_static.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"
GetCharType<>::Type:
GetCharType<std::wstring>::Type //equals wchar_t
GetCharType<wchar_t[5]> ::Type //equals wchar_t
strLength():
strLength(str); //equals str.length()
strLength(array); //equals cStringLength(array)
strBegin(): -> not null-terminated! -> may be nullptr if length is 0!
std::wstring str(L"dummy");
char array[] = "dummy";
strBegin(str); //returns str.c_str()
strBegin(array); //returns array
*/
//reference a sub-string for consumption by zen string_tools
template <class Char>
class StringRef
{
public:
template <class Iterator>
StringRef(Iterator first, Iterator last) : length_(last - first), data_(first != last ? &*first : nullptr) {}
size_t length() const { return length_; }
const Char* data() const { return data_; } //1. no null-termination! 2. may be nullptr!
private:
size_t length_;
const Char* data_;
};
//---------------------- implementation ----------------------
namespace implementation
{
template<class S, class Char> //test if result of S::c_str() can convert to const Char*
class HasConversion
{
typedef char Yes[1];
typedef char No [2];
static Yes& hasConversion(const Char*);
static No& hasConversion(...);
static S& createInstance();
public:
enum { value = sizeof(hasConversion(createInstance().c_str())) == sizeof(Yes) };
};
template <class S, bool isStringClass> struct GetCharTypeImpl : ResultType<NullType> {};
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>
{
//typedef typename S::value_type Type;
/*DON'T use S::value_type:
1. support Glib::ustring: value_type is "unsigned int" but c_str() returns "const char*"
2. wxString, wxWidgets v2.9, has some questionable string design: wxString::c_str() returns a proxy (wxCStrData) which
is implicitly convertible to *both* "const char*" and "const wchar_t*" while wxString::value_type is a wrapper around an unsigned int
*/
};
template <> struct GetCharTypeImpl<char, false> : ResultType<char > {};
template <> struct GetCharTypeImpl<wchar_t, false> : ResultType<wchar_t> {};
ZEN_INIT_DETECT_MEMBER_TYPE(value_type);
ZEN_INIT_DETECT_MEMBER(c_str); //we don't know the exact declaration of the member attribute and it may be in a base class!
ZEN_INIT_DETECT_MEMBER(length); //
template <class S>
class StringTraits
{
typedef typename RemoveRef <S >::Type NonRefType;
typedef typename RemoveConst <NonRefType >::Type NonConstType;
typedef typename RemoveArray <NonConstType>::Type NonArrayType;
typedef typename RemovePointer<NonArrayType>::Type NonPtrType;
typedef typename RemoveConst <NonPtrType >::Type UndecoratedType; //handle "const char* const"
public:
enum
{
isStringClass = HasMemberType_value_type<NonConstType>::value &&
HasMember_c_str <NonConstType>::value &&
HasMember_length <NonConstType>::value
};
typedef typename GetCharTypeImpl<UndecoratedType, isStringClass>::Type CharType;
enum
{
isStringLike = IsSameType<CharType, char>::value ||
IsSameType<CharType, wchar_t>::value
};
};
template <> class StringTraits<StringRef<char>>
{
public:
enum
{
isStringClass = false,
isStringLike = true
};
typedef char CharType;
};
template <> class StringTraits<StringRef<wchar_t>>
{
public:
enum
{
isStringClass = false,
isStringLike = true
};
typedef wchar_t CharType;
};
}
template <class T>
struct IsStringLike : StaticBool<implementation::StringTraits<T>::isStringLike> {};
template <class T>
struct GetCharType : ResultType<typename implementation::StringTraits<T>::CharType> {};
namespace implementation
{
template <class C> inline
size_t cStringLength(const C* str) //strlen()
{
assert_static((IsSameType<C, char>::value || IsSameType<C, wchar_t>::value));
size_t len = 0;
while (*str++ != 0)
++len;
return len;
}
}
template <class S> inline
const typename GetCharType<S>::Type* strBegin(const S& str, typename EnableIf<implementation::StringTraits<S>::isStringClass>::Type* = nullptr) //SFINAE: T must be a "string"
{
return str.c_str();
}
inline const char* strBegin(const char* str) { return str; }
inline const wchar_t* strBegin(const wchar_t* str) { return str; }
inline const char* strBegin(const char& ch) { return &ch; }
inline const wchar_t* strBegin(const wchar_t& ch) { return &ch; }
inline const char* strBegin(const StringRef<char >& ref) { return ref.data(); }
inline const wchar_t* strBegin(const StringRef<wchar_t>& ref) { return ref.data(); }
template <class S> inline
size_t strLength(const S& str, typename EnableIf<implementation::StringTraits<S>::isStringClass>::Type* = nullptr) //SFINAE: T must be a "string"
{
return str.length();
}
inline size_t strLength(const char* str) { return implementation::cStringLength(str); }
inline size_t strLength(const wchar_t* str) { return implementation::cStringLength(str); }
inline size_t strLength(char) { return 1; }
inline size_t strLength(wchar_t) { return 1; }
inline size_t strLength(const StringRef<char >& ref) { return ref.length(); }
inline size_t strLength(const StringRef<wchar_t>& ref) { return ref.length(); }
}
#endif //STRING_TRAITS_HEADER_813274321443234
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