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1/////////////////////////////////////////////////////////////////////////////
2// Name: variant.h
3// Purpose: interface of wxVariant
4// Author: wxWidgets team
5// RCS-ID: $Id$
6// Licence: wxWindows licence
7/////////////////////////////////////////////////////////////////////////////
8
9/**
10 @class wxVariant
11
12 The wxVariant class represents a container for any type. A variant's value
13 can be changed at run time, possibly to a different type of value.
14
15 @note As of wxWidgets 2.9.1, wxAny has become the preferred variant class.
16 While most controls still use wxVariant in their interface, you
17 can start using wxAny in your code because of an implicit conversion
18 layer. See below for more information.
19
20 As standard, wxVariant can store values of type bool, wxChar, double, long,
21 string, string list, time, date, void pointer, list of strings, and list of
22 variants. However, an application can extend wxVariant's capabilities by
23 deriving from the class wxVariantData and using the wxVariantData form of
24 the wxVariant constructor or assignment operator to assign this data to a
25 variant. Actual values for user-defined types will need to be accessed via
26 the wxVariantData object, unlike the case for basic data types where
27 convenience functions such as GetLong() can be used.
28
29 Pointers to any wxObject derived class can also easily be stored in a
30 wxVariant. wxVariant will then use wxWidgets' built-in RTTI system to set
31 the type name (returned by GetType()) and to perform type-safety checks at
32 runtime.
33
34 This class is useful for reducing the programming for certain tasks, such
35 as an editor for different data types, or a remote procedure call protocol.
36
37 An optional name member is associated with a wxVariant. This might be used,
38 for example, in CORBA or OLE automation classes, where named parameters are
39 required.
40
41 Note that as of wxWidgets 2.7.1, wxVariant is
42 @ref overview_refcount "reference counted". Additionally, the convenience
43 macros DECLARE_VARIANT_OBJECT() and IMPLEMENT_VARIANT_OBJECT() were added
44 so that adding (limited) support for conversion to and from wxVariant can
45 be very easily implemented without modifying either wxVariant or the class
46 to be stored by wxVariant. Since assignment operators cannot be declared
47 outside the class, the shift left operators are used like this:
48
49 @code
50 // in the header file
51 DECLARE_VARIANT_OBJECT(MyClass)
52
53 // in the implementation file
54 IMPLEMENT_VARIANT_OBJECT(MyClass)
55
56 // in the user code
57 wxVariant variant;
58 MyClass value;
59 variant << value;
60
61 // or
62 value << variant;
63 @endcode
64
65 For this to work, MyClass must derive from wxObject, implement the
66 @ref overview_rtti "wxWidgets RTTI system" and support the assignment
67 operator and equality operator for itself. Ideally, it should also be
68 reference counted to make copying operations cheap and fast. This can be
69 most easily implemented using the reference counting support offered by
70 wxObject itself. By default, wxWidgets already implements the shift
71 operator conversion for a few of its drawing related classes:
72
73 @code
74 IMPLEMENT_VARIANT_OBJECT(wxColour)
75 IMPLEMENT_VARIANT_OBJECT(wxImage)
76 IMPLEMENT_VARIANT_OBJECT(wxIcon)
77 IMPLEMENT_VARIANT_OBJECT(wxBitmap)
78 @endcode
79
80 Note that as of wxWidgets 2.9.0, wxVariantData no longer inherits from
81 wxObject and wxVariant no longer uses the type-unsafe wxList class for list
82 operations but the type-safe wxVariantList class. Also, wxVariantData now
83 supports the wxVariantData::Clone() function for implementing the Unshare()
84 function. wxVariantData::Clone() is implemented automatically by
85 IMPLEMENT_VARIANT_OBJECT().
86
87 Since wxVariantData no longer derives from wxObject, any code that tests
88 the type of the data using wxDynamicCast() will require adjustment. You can
89 use the macro wxDynamicCastVariantData() with the same arguments as
90 wxDynamicCast(), to use C++ RTTI type information instead of wxWidgets
91 RTTI.
92
93 @section variant_wxanyconversion wxVariant to wxAny Conversion Layer
94
95 wxAny is a more modern, template-based variant class. It is not
96 directly compatible with wxVariant, but there is a transparent conversion
97 layer.
98
99 Following is an example how to use these conversions with wxPropertyGrid's
100 property class wxPGProperty (which currently uses wxVariants both
101 internally and in the public API):
102
103 @code
104 // Get property value as wxAny instead of wxVariant
105 wxAny value = property->GetValue();
106
107 // Do something with it
108 DoSomethingWithString(value.As<wxString>());
109
110 // Write back new value to property
111 value = "New Value";
112 property->SetValue(value);
113
114 @endcode
115
116 Some caveats:
117 @li In wxAny, there are no separate types for handling integers of
118 different sizes, so converting wxAny with 'long long' value
119 will yield wxVariant of "long" type when the value is small
120 enough to fit in without overflow. Otherwise, variant type
121 "longlong" is used. Also note that wxAny holding unsigned integer
122 will always be converted to "ulonglong" wxVariant type.
123
124 @li Unlike wxVariant, wxAny does not store a (rarely needed) name string.
125
126 @li Because of implicit conversion of wxVariant to wxAny, wxAny cannot
127 usually contain value of type wxVariant. In other words,
128 any.CheckType<wxVariant>() can never return @true.
129
130 Supplied conversion functions will automatically work with all
131 built-in wxVariant types, and also with all user-specified types generated
132 using IMPLEMENT_VARIANT_OBJECT(). For hand-built wxVariantData classes,
133 you will need to use supplied macros in a following manner:
134
135 @code
136
137 // Declare wxVariantData for data type Foo
138 class wxVariantDataFoo: public wxVariantData
139 {
140 public:
141 // interface
142 // ...
143
144 DECLARE_WXANY_CONVERSION()
145 protected:
146 // data storage etc
147 // ...
148 };
149
150 IMPLEMENT_TRIVIAL_WXANY_CONVERSION(Foo, wxVariantDataFoo)
151
152 @endcode
153
154 @library{wxbase}
155 @category{data}
156
157 @see wxVariantData, wxAny
158*/
159class wxVariant : public wxObject
160{
161public:
162 /**
163 Default constructor.
164 */
165 wxVariant();
166
167 /**
168 Constructs a variant directly with a wxVariantData object. wxVariant
169 will take ownership of the wxVariantData and will not increase its
170 reference count.
171 */
172 wxVariant(wxVariantData* data, const wxString& name = wxEmptyString);
173
174 /**
175 Constructs a variant from another variant by increasing the reference
176 count.
177 */
178 wxVariant(const wxVariant& variant);
179
180 /**
181 Constructs a variant by converting it from wxAny.
182 */
183 wxVariant(const wxAny& any);
184
185 /**
186 Constructs a variant from a wide string literal.
187 */
188 wxVariant(const wxChar* value, const wxString& name = wxEmptyString);
189
190 /**
191 Constructs a variant from a string.
192 */
193 wxVariant(const wxString& value, const wxString& name = wxEmptyString);
194
195 /**
196 Constructs a variant from a wide char.
197 */
198 wxVariant(wxChar value, const wxString& name = wxEmptyString);
199
200 /**
201 Constructs a variant from a long.
202 */
203 wxVariant(long value, const wxString& name = wxEmptyString);
204
205 /**
206 Constructs a variant from a bool.
207 */
208 wxVariant(bool value, const wxString& name = wxEmptyString);
209
210 /**
211 Constructs a variant from a double.
212 */
213 wxVariant(double value, const wxString& name = wxEmptyString);
214
215 /**
216 Constructs a variant from a wxLongLong.
217 */
218 wxVariant(wxLongLong value, const wxString& name = wxEmptyString);
219
220 /**
221 Constructs a variant from a wxULongLong.
222 */
223 wxVariant(wxULongLong value, const wxString& name = wxEmptyString);
224
225 /**
226 Constructs a variant from a list of variants
227 */
228 wxVariant(const wxVariantList& value, const wxString& name = wxEmptyString);
229
230 /**
231 Constructs a variant from a void pointer.
232 */
233 wxVariant(void* value, const wxString& name = wxEmptyString);
234
235 /**
236 Constructs a variant from a pointer to an wxObject
237 derived class.
238 */
239 wxVariant(wxObject* value, const wxString& name = wxEmptyString);
240
241 /**
242 Constructs a variant from a wxDateTime.
243 */
244 wxVariant(const wxDateTime& val, const wxString& name = wxEmptyString);
245
246 /**
247 Constructs a variant from a wxArrayString.
248 */
249 wxVariant(const wxArrayString& val, const wxString& name = wxEmptyString);
250
251 /**
252 Destructor.
253
254 @note wxVariantData's destructor is protected, so wxVariantData cannot
255 usually be deleted. Instead, wxVariantData::DecRef() should be
256 called. See @ref overview_refcount_destruct
257 "reference-counted object destruction" for more info.
258 */
259 virtual ~wxVariant();
260
261
262 /**
263 @name List Functionality
264 */
265 //@{
266
267 /**
268 Returns the value at @a idx (zero-based).
269 */
270 wxVariant operator [](size_t idx) const;
271 /**
272 Returns a reference to the value at @a idx (zero-based). This can be
273 used to change the value at this index.
274 */
275 wxVariant& operator [](size_t idx);
276
277 /**
278 Appends a value to the list.
279 */
280 void Append(const wxVariant& value);
281
282 /**
283 Makes the variant null by deleting the internal data and set the name
284 to wxEmptyString.
285 */
286 void Clear();
287
288 /**
289 Deletes the contents of the list.
290 */
291 void ClearList();
292
293 /**
294 Deletes the zero-based @a item from the list.
295 */
296 bool Delete(size_t item);
297
298 /**
299 Returns the number of elements in the list.
300 */
301 size_t GetCount() const;
302
303 /**
304 Returns a reference to the wxVariantList class used by wxVariant if
305 this wxVariant is currently a list of variants.
306 */
307 wxVariantList& GetList() const;
308
309 /**
310 Inserts a value at the front of the list.
311 */
312 void Insert(const wxVariant& value);
313
314 /**
315 Makes an empty list. This differs from a null variant which has no
316 data; a null list is of type list, but the number of elements in the
317 list is zero.
318 */
319 void NullList();
320
321 //@}
322
323
324 //@{
325 /**
326 Retrieves and converts the value of this variant to the type that
327 @a value is.
328 */
329 bool Convert(long* value) const;
330 bool Convert(bool* value) const;
331 bool Convert(double* value) const;
332 bool Convert(wxString* value) const;
333 bool Convert(wxChar* value) const;
334 bool Convert(wxLongLong* value) const;
335 bool Convert(wxULongLong* value) const;
336 bool Convert(wxDateTime* value) const;
337 //@}
338
339 /**
340 Converts wxVariant into wxAny.
341 */
342 wxAny GetAny() const;
343
344 /**
345 Returns the string array value.
346 */
347 wxArrayString GetArrayString() const;
348
349 /**
350 Returns the boolean value.
351 */
352 bool GetBool() const;
353
354 /**
355 Returns the character value.
356 */
357 wxUniChar GetChar() const;
358
359 /**
360 Returns a pointer to the internal variant data. To take ownership of
361 this data, you must call its wxVariantData::IncRef() method. When you
362 stop using it, wxVariantData::DecRef() must be called as well.
363 */
364 wxVariantData* GetData() const;
365
366 /**
367 Returns the date value.
368 */
369 wxDateTime GetDateTime() const;
370
371 /**
372 Returns the floating point value.
373 */
374 double GetDouble() const;
375
376 /**
377 Returns the integer value.
378 */
379 long GetLong() const;
380
381 /**
382 Returns the signed 64-bit integer value.
383 */
384 wxLongLong GetLongLong() const;
385
386 /**
387 Returns a constant reference to the variant name.
388 */
389 const wxString& GetName() const;
390
391 /**
392 Gets the string value.
393 */
394 wxString GetString() const;
395
396 /**
397 Returns the value type as a string.
398
399 The built-in types are:
400 - "bool"
401 - "char"
402 - "datetime"
403 - "double"
404 - "list"
405 - "long"
406 - "longlong"
407 - "string"
408 - "ulonglong"
409 - "arrstring"
410 - "void*"
411
412 If the variant is null, the value type returned is the string "null"
413 (not the empty string).
414 */
415 wxString GetType() const;
416
417 /**
418 Returns the unsigned 64-bit integer value.
419 */
420 wxULongLong GetULongLong() const;
421
422 /**
423 Gets the void pointer value.
424
425 Notice that this method can be used for null objects (i.e. those for
426 which IsNull() returns @true) and will return @NULL for them.
427 */
428 void* GetVoidPtr() const;
429
430 /**
431 Gets the wxObject pointer value.
432 */
433 wxObject* GetWxObjectPtr() const;
434
435 /**
436 Returns @true if there is no data associated with this variant, @false
437 if there is data.
438 */
439 bool IsNull() const;
440
441 /**
442 Returns @true if @a type matches the type of the variant, @false
443 otherwise.
444 */
445 bool IsType(const wxString& type) const;
446
447 /**
448 Returns @true if the data is derived from the class described by
449 @a type, @false otherwise.
450 */
451 bool IsValueKindOf(const wxClassInfo* type) const;
452
453 /**
454 Makes the variant null by deleting the internal data.
455 */
456 void MakeNull();
457
458 /**
459 Makes a string representation of the variant value (for any type).
460 */
461 wxString MakeString() const;
462
463 /**
464 Returns @true if @a value matches an element in the list.
465 */
466 bool Member(const wxVariant& value) const;
467
468 /**
469 Sets the internal variant data, deleting the existing data if there is
470 any.
471 */
472 void SetData(wxVariantData* data);
473
474 /**
475 Makes sure that any data associated with this variant is not shared
476 with other variants. For this to work, wxVariantData::Clone() must be
477 implemented for the data types you are working with.
478 wxVariantData::Clone() is implemented for all the default data types.
479 */
480 bool Unshare();
481
482 //@{
483 /**
484 Inequality test operator.
485 */
486 bool operator !=(const wxVariant& value) const;
487 bool operator !=(const wxString& value) const;
488 bool operator !=(const wxChar* value) const;
489 bool operator !=(wxChar value) const;
490 bool operator !=(long value) const;
491 bool operator !=(bool value) const;
492 bool operator !=(double value) const;
493 bool operator !=(wxLongLong value) const;
494 bool operator !=(wxULongLong value) const;
495 bool operator !=(void* value) const;
496 bool operator !=(wxObject* value) const;
497 bool operator !=(const wxVariantList& value) const;
498 bool operator !=(const wxArrayString& value) const;
499 bool operator !=(const wxDateTime& value) const;
500 //@}
501
502 //@{
503 /**
504 Assignment operator, using @ref overview_refcount "reference counting"
505 if possible.
506 */
507 void operator =(const wxVariant& value);
508 void operator =(wxVariantData* value);
509 void operator =(const wxString& value);
510 void operator =(const wxChar* value);
511 void operator =(wxChar value);
512 void operator =(long value);
513 void operator =(bool value);
514 void operator =(double value);
515 bool operator =(wxLongLong value) const;
516 bool operator =(wxULongLong value) const;
517 void operator =(void* value);
518 void operator =(wxObject* value);
519 void operator =(const wxVariantList& value);
520 void operator =(const wxDateTime& value);
521 void operator =(const wxArrayString& value);
522 //@}
523
524 //@{
525 /**
526 Equality test operator.
527 */
528 bool operator ==(const wxVariant& value) const;
529 bool operator ==(const wxString& value) const;
530 bool operator ==(const wxChar* value) const;
531 bool operator ==(wxChar value) const;
532 bool operator ==(long value) const;
533 bool operator ==(bool value) const;
534 bool operator ==(double value) const;
535 bool operator ==(wxLongLong value) const;
536 bool operator ==(wxULongLong value) const;
537 bool operator ==(void* value) const;
538 bool operator ==(wxObject* value) const;
539 bool operator ==(const wxVariantList& value) const;
540 bool operator ==(const wxArrayString& value) const;
541 bool operator ==(const wxDateTime& value) const;
542 //@}
543
544 //@{
545 /**
546 Operators for implicit conversion, using appropriate getter member
547 function.
548 */
549 double operator double() const;
550 long operator long() const;
551 wxLongLong operator wxLongLong() const;
552 wxULongLong operator wxULongLong() const;
553 //@}
554
555 /**
556 Operator for implicit conversion to a pointer to a void, using
557 GetVoidPtr().
558 */
559 void* operator void*() const;
560
561 /**
562 Operator for implicit conversion to a wxChar, using GetChar().
563 */
564 char operator wxChar() const;
565
566 /**
567 Operator for implicit conversion to a pointer to a wxDateTime, using
568 GetDateTime().
569 */
570 void* operator wxDateTime() const;
571
572 /**
573 Operator for implicit conversion to a string, using MakeString().
574 */
575 wxString operator wxString() const;
576};
577
578
579
580/**
581 @class wxVariantData
582
583 The wxVariantData class is used to implement a new type for wxVariant.
584 Derive from wxVariantData, and override the pure virtual functions.
585
586 wxVariantData is @ref overview_refcount "reference counted", but you don't
587 normally have to care about this, as wxVariant manages the count
588 automatically. However, in case your application needs to take ownership of
589 wxVariantData, be aware that the object is created with a reference count
590 of 1, and passing it to wxVariant will not increase this. In other words,
591 IncRef() needs to be called only if you both take ownership of
592 wxVariantData and pass it to a wxVariant. Also note that the destructor is
593 protected, so you can never explicitly delete a wxVariantData instance.
594 Instead, DecRef() will delete the object automatically when the reference
595 count reaches zero.
596
597 @library{wxbase}
598 @category{data}
599
600 @see wxVariant, wxGetVariantCast()
601*/
602class wxVariantData : public wxObjectRefData
603{
604public:
605 /**
606 Default constructor.
607 */
608 wxVariantData();
609
610 /**
611 This function can be overridden to clone the data. You must implement
612 this function in order for wxVariant::Unshare() to work for your data.
613 This function is implemented for all built-in data types.
614 */
615 virtual wxVariantData* Clone() const;
616
617 /**
618 Decreases reference count. If the count reaches zero, the object is
619 automatically deleted.
620
621 @note The destructor of wxVariantData is protected, so delete cannot be
622 used as normal. Instead, DecRef() should be called.
623 */
624 void DecRef();
625
626 /**
627 Returns @true if this object is equal to @a data.
628 */
629 virtual bool Eq(wxVariantData& data) const = 0;
630
631 /**
632 Converts value to wxAny, if possible. Return @true if successful.
633 */
634 virtual bool GetAny(wxAny* any) const;
635
636 /**
637 Returns the string type of the data.
638 */
639 virtual wxString GetType() const = 0;
640
641 /**
642 If the data is a wxObject returns a pointer to the objects wxClassInfo
643 structure, if the data isn't a wxObject the method returns @NULL.
644 */
645 virtual wxClassInfo* GetValueClassInfo();
646
647 /**
648 Increases reference count. Note that initially wxVariantData has
649 reference count of 1.
650 */
651 void IncRef();
652
653 /**
654 Reads the data from @a stream.
655 */
656 virtual bool Read(istream& stream);
657
658 /**
659 Reads the data from @a string.
660 */
661 virtual bool Read(wxString& string);
662
663 /**
664 Writes the data to @a stream.
665 */
666 virtual bool Write(ostream& stream) const;
667 /**
668 Writes the data to @a string.
669 */
670 virtual bool Write(wxString& string) const;
671};
672
673
674
675// ============================================================================
676// Global functions/macros
677// ============================================================================
678
679/** @addtogroup group_funcmacro_rtti */
680//@{
681
682/**
683 This macro returns a pointer to the data stored in @a var (wxVariant) cast
684 to the type @a classname if the data is of this type (the check is done
685 during the run-time) or @NULL otherwise.
686
687 @header{wx/variant.h}
688
689 @see @ref overview_rtti, wxDynamicCast()
690*/
691#define wxGetVariantCast(var, classname)
692
693//@}
694