1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
|
// **************************************************************************
// * 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) ZenJu (zhnmju123 AT gmx DOT de) - All Rights Reserved *
// **************************************************************************
#ifndef STRING_TRAITS_HEADER_813274321443234
#define STRING_TRAITS_HEADER_813274321443234
#include "type_tools.h"
#include "type_traits.h"
#include "assert_static.h"
//uniform access to string-like types, both classes and character arrays
namespace zen
{
/*
IsStringLike<>::result:
IsStringLike<const wchar_t*>::result; //equals "true"
IsStringLike<const int*> ::result; //equals "false"
GetCharType<>::Result:
GetCharType<std::wstring>::Result //equals wchar_t
GetCharType<wchar_t[5]> ::Result //equals wchar_t
strBegin():
std::wstring str(L"dummy");
char array[] = "dummy";
strBegin(str); //returns str.c_str()
strBegin(array); //returns array
strLength():
strLength(str); //equals str.length()
strLength(array); //equals cStringLength(array)
*/
//wrap a sub-string or a char* as an intermediate string class when the length is already known
template <class Char>
class StringProxy
{
public:
StringProxy(const Char* cstr, size_t len ) : cstr_(cstr), length_(len) {}
StringProxy(const Char* cstrBegin, const Char* cstrEnd) : cstr_(cstrBegin), length_(cstrEnd - cstrBegin) {}
const Char* c_str() const { return cstr_; }
size_t length() const { return length_; }
private:
const Char* cstr_;
size_t length_;
};
//---------------------- implementation ----------------------
namespace implementation
{
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<typename T, bool isClassType>
struct HasStringMembers { enum { result = false }; };
template<typename T>
struct HasStringMembers<T, true> //Note: we can apply non-typed member-check on class types only!
{
enum { result = HasMember_c_str <T>::result &&
HasMember_length<T>::result
};
};
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 { result = sizeof(hasConversion(createInstance().c_str())) == sizeof(Yes) };
};
template <class S, bool isStringClass> struct GetCharTypeImpl { typedef EmptyType Result; };
template <class S> struct GetCharTypeImpl<S, true >
{
//typedef typename S::value_type Result;
/*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
*/
typedef typename SelectIf<HasConversion<S, wchar_t>::result, wchar_t,
typename SelectIf<HasConversion<S, char>::result, char, EmptyType>::Result
>::Result Result;
};
template <> struct GetCharTypeImpl<char, false> { typedef char Result; };
template <> struct GetCharTypeImpl<wchar_t, false> { typedef wchar_t Result; };
ZEN_INIT_DETECT_MEMBER_TYPE(value_type);
template <class S>
class StringTraits
{
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 = HasStringMembers<NonConstType, HasMemberType_value_type<NonConstType>::result>::result
};
typedef typename GetCharTypeImpl<UndecoratedType, isStringClass>::Result CharType;
enum
{
isStringLike = IsSameType<CharType, char>::result ||
IsSameType<CharType, wchar_t>::result
};
};
}
template <class T>
struct IsStringLike { enum { result = implementation::StringTraits<T>::isStringLike }; };
template <class T>
struct GetCharType { typedef typename implementation::StringTraits<T>::CharType 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 GetCharType<S>::Result* strBegin(const S& str, typename EnableIf<implementation::StringTraits<S>::isStringClass>::Result* = NULL) //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; }
template <class S> inline
size_t strLength(const S& str, typename EnableIf<implementation::StringTraits<S>::isStringClass>::Result* = NULL) //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; }
}
#endif //STRING_TRAITS_HEADER_813274321443234
|
