///////////////////////////////////////////////////////////////////////////// // Name: variant.h // Purpose: interface of wxVariant // Author: wxWidgets team // RCS-ID: $Id$ // Licence: wxWindows licence ///////////////////////////////////////////////////////////////////////////// /** @class wxVariant The wxVariant class represents a container for any type. A variant's value can be changed at run time, possibly to a different type of value. @note As of wxWidgets 2.9.1, wxAny has become the preferred variant class. While most controls still use wxVariant in their interface, you can start using wxAny in your code because of an implicit conversion layer. See below for more information. As standard, wxVariant can store values of type bool, wxChar, double, long, string, string list, time, date, void pointer, list of strings, and list of variants. However, an application can extend wxVariant's capabilities by deriving from the class wxVariantData and using the wxVariantData form of the wxVariant constructor or assignment operator to assign this data to a variant. Actual values for user-defined types will need to be accessed via the wxVariantData object, unlike the case for basic data types where convenience functions such as GetLong() can be used. Pointers to any wxObject derived class can also easily be stored in a wxVariant. wxVariant will then use wxWidgets' built-in RTTI system to set the type name (returned by GetType()) and to perform type-safety checks at runtime. This class is useful for reducing the programming for certain tasks, such as an editor for different data types, or a remote procedure call protocol. An optional name member is associated with a wxVariant. This might be used, for example, in CORBA or OLE automation classes, where named parameters are required. Note that as of wxWidgets 2.7.1, wxVariant is @ref overview_refcount "reference counted". Additionally, the convenience macros DECLARE_VARIANT_OBJECT() and IMPLEMENT_VARIANT_OBJECT() were added so that adding (limited) support for conversion to and from wxVariant can be very easily implemented without modifying either wxVariant or the class to be stored by wxVariant. Since assignment operators cannot be declared outside the class, the shift left operators are used like this: @code // in the header file DECLARE_VARIANT_OBJECT(MyClass) // in the implementation file IMPLEMENT_VARIANT_OBJECT(MyClass) // in the user code wxVariant variant; MyClass value; variant << value; // or value << variant; @endcode For this to work, MyClass must derive from wxObject, implement the @ref overview_rtti "wxWidgets RTTI system" and support the assignment operator and equality operator for itself. Ideally, it should also be reference counted to make copying operations cheap and fast. This can be most easily implemented using the reference counting support offered by wxObject itself. By default, wxWidgets already implements the shift operator conversion for a few of its drawing related classes: @code IMPLEMENT_VARIANT_OBJECT(wxColour) IMPLEMENT_VARIANT_OBJECT(wxImage) IMPLEMENT_VARIANT_OBJECT(wxIcon) IMPLEMENT_VARIANT_OBJECT(wxBitmap) @endcode Note that as of wxWidgets 2.9.0, wxVariantData no longer inherits from wxObject and wxVariant no longer uses the type-unsafe wxList class for list operations but the type-safe wxVariantList class. Also, wxVariantData now supports the wxVariantData::Clone() function for implementing the Unshare() function. wxVariantData::Clone() is implemented automatically by IMPLEMENT_VARIANT_OBJECT(). Since wxVariantData no longer derives from wxObject, any code that tests the type of the data using wxDynamicCast() will require adjustment. You can use the macro wxDynamicCastVariantData() with the same arguments as wxDynamicCast(), to use C++ RTTI type information instead of wxWidgets RTTI. @section variant_wxanyconversion wxVariant to wxAny Conversion Layer wxAny is a more modern, template-based variant class. It is not directly compatible with wxVariant, but there is a transparent conversion layer. Following is an example how to use these conversions with wxPropertyGrid's property class wxPGProperty (which currently uses wxVariants both internally and in the public API): @code // Get property value as wxAny instead of wxVariant wxAny value = property->GetValue(); // Do something with it DoSomethingWithString(value.As()); // Write back new value to property value = "New Value"; property->SetValue(value); @endcode Some caveats: @li In wxAny, there are no separate types for handling integers of different sizes, so converting wxAny with 'long long' value will yield wxVariant of "long" type when the value is small enough to fit in without overflow. Otherwise, variant type "longlong" is used. Also note that wxAny holding unsigned integer will always be converted to "ulonglong" wxVariant type. @li Unlike wxVariant, wxAny does not store a (rarely needed) name string. @li Because of implicit conversion of wxVariant to wxAny, wxAny cannot usually contain value of type wxVariant. In other words, any.CheckType() can never return @true. Supplied conversion functions will automatically work with all built-in wxVariant types, and also with all user-specified types generated using IMPLEMENT_VARIANT_OBJECT(). For hand-built wxVariantData classes, you will need to use supplied macros in a following manner: @code // Declare wxVariantData for data type Foo class wxVariantDataFoo: public wxVariantData { public: // interface // ... DECLARE_WXANY_CONVERSION() protected: // data storage etc // ... }; IMPLEMENT_TRIVIAL_WXANY_CONVERSION(Foo, wxVariantDataFoo) @endcode @library{wxbase} @category{data} @see wxVariantData, wxAny */ class wxVariant : public wxObject { public: /** Default constructor. */ wxVariant(); /** Constructs a variant directly with a wxVariantData object. wxVariant will take ownership of the wxVariantData and will not increase its reference count. */ wxVariant(wxVariantData* data, const wxString& name = wxEmptyString); /** Constructs a variant from another variant by increasing the reference count. */ wxVariant(const wxVariant& variant); /** Constructs a variant by converting it from wxAny. */ wxVariant(const wxAny& any); /** Constructs a variant from a wide string literal. */ wxVariant(const wxChar* value, const wxString& name = wxEmptyString); /** Constructs a variant from a string. */ wxVariant(const wxString& value, const wxString& name = wxEmptyString); /** Constructs a variant from a wide char. */ wxVariant(wxChar value, const wxString& name = wxEmptyString); /** Constructs a variant from a long. */ wxVariant(long value, const wxString& name = wxEmptyString); /** Constructs a variant from a bool. */ wxVariant(bool value, const wxString& name = wxEmptyString); /** Constructs a variant from a double. */ wxVariant(double value, const wxString& name = wxEmptyString); /** Constructs a variant from a wxLongLong. */ wxVariant(wxLongLong value, const wxString& name = wxEmptyString); /** Constructs a variant from a wxULongLong. */ wxVariant(wxULongLong value, const wxString& name = wxEmptyString); /** Constructs a variant from a list of variants */ wxVariant(const wxVariantList& value, const wxString& name = wxEmptyString); /** Constructs a variant from a void pointer. */ wxVariant(void* value, const wxString& name = wxEmptyString); /** Constructs a variant from a pointer to an wxObject derived class. */ wxVariant(wxObject* value, const wxString& name = wxEmptyString); /** Constructs a variant from a wxDateTime. */ wxVariant(const wxDateTime& val, const wxString& name = wxEmptyString); /** Constructs a variant from a wxArrayString. */ wxVariant(const wxArrayString& val, const wxString& name = wxEmptyString); /** Destructor. @note wxVariantData's destructor is protected, so wxVariantData cannot usually be deleted. Instead, wxVariantData::DecRef() should be called. See @ref overview_refcount_destruct "reference-counted object destruction" for more info. */ virtual ~wxVariant(); /** @name List Functionality */ //@{ /** Returns the value at @a idx (zero-based). */ wxVariant operator [](size_t idx) const; /** Returns a reference to the value at @a idx (zero-based). This can be used to change the value at this index. */ wxVariant& operator [](size_t idx); /** Appends a value to the list. */ void Append(const wxVariant& value); /** Makes the variant null by deleting the internal data and set the name to wxEmptyString. */ void Clear(); /** Deletes the contents of the list. */ void ClearList(); /** Deletes the zero-based @a item from the list. */ bool Delete(size_t item); /** Returns the number of elements in the list. */ size_t GetCount() const; /** Returns a reference to the wxVariantList class used by wxVariant if this wxVariant is currently a list of variants. */ wxVariantList& GetList() const; /** Inserts a value at the front of the list. */ void Insert(const wxVariant& value); /** Makes an empty list. This differs from a null variant which has no data; a null list is of type list, but the number of elements in the list is zero. */ void NullList(); //@} //@{ /** Retrieves and converts the value of this variant to the type that @a value is. */ bool Convert(long* value) const; bool Convert(bool* value) const; bool Convert(double* value) const; bool Convert(wxString* value) const; bool Convert(wxChar* value) const; bool Convert(wxLongLong* value) const; bool Convert(wxULongLong* value) const; bool Convert(wxDateTime* value) const; //@} /** Converts wxVariant into wxAny. */ wxAny GetAny() const; /** Returns the string array value. */ wxArrayString GetArrayString() const; /** Returns the boolean value. */ bool GetBool() const; /** Returns the character value. */ wxUniChar GetChar() const; /** Returns a pointer to the internal variant data. To take ownership of this data, you must call its wxVariantData::IncRef() method. When you stop using it, wxVariantData::DecRef() must be called as well. */ wxVariantData* GetData() const; /** Returns the date value. */ wxDateTime GetDateTime() const; /** Returns the floating point value. */ double GetDouble() const; /** Returns the integer value. */ long GetLong() const; /** Returns the signed 64-bit integer value. */ wxLongLong GetLongLong() const; /** Returns a constant reference to the variant name. */ const wxString& GetName() const; /** Gets the string value. */ wxString GetString() const; /** Returns the value type as a string. The built-in types are: - "bool" - "char" - "datetime" - "double" - "list" - "long" - "longlong" - "string" - "ulonglong" - "arrstring" - "void*" If the variant is null, the value type returned is the string "null" (not the empty string). */ wxString GetType() const; /** Returns the unsigned 64-bit integer value. */ wxULongLong GetULongLong() const; /** Gets the void pointer value. Notice that this method can be used for null objects (i.e. those for which IsNull() returns @true) and will return @NULL for them. */ void* GetVoidPtr() const; /** Gets the wxObject pointer value. */ wxObject* GetWxObjectPtr() const; /** Returns @true if there is no data associated with this variant, @false if there is data. */ bool IsNull() const; /** Returns @true if @a type matches the type of the variant, @false otherwise. */ bool IsType(const wxString& type) const; /** Returns @true if the data is derived from the class described by @a type, @false otherwise. */ bool IsValueKindOf(const wxClassInfo* type) const; /** Makes the variant null by deleting the internal data. */ void MakeNull(); /** Makes a string representation of the variant value (for any type). */ wxString MakeString() const; /** Returns @true if @a value matches an element in the list. */ bool Member(const wxVariant& value) const; /** Sets the internal variant data, deleting the existing data if there is any. */ void SetData(wxVariantData* data); /** Makes sure that any data associated with this variant is not shared with other variants. For this to work, wxVariantData::Clone() must be implemented for the data types you are working with. wxVariantData::Clone() is implemented for all the default data types. */ bool Unshare(); //@{ /** Inequality test operator. */ bool operator !=(const wxVariant& value) const; bool operator !=(const wxString& value) const; bool operator !=(const wxChar* value) const; bool operator !=(wxChar value) const; bool operator !=(long value) const; bool operator !=(bool value) const; bool operator !=(double value) const; bool operator !=(wxLongLong value) const; bool operator !=(wxULongLong value) const; bool operator !=(void* value) const; bool operator !=(wxObject* value) const; bool operator !=(const wxVariantList& value) const; bool operator !=(const wxArrayString& value) const; bool operator !=(const wxDateTime& value) const; //@} //@{ /** Assignment operator, using @ref overview_refcount "reference counting" if possible. */ void operator =(const wxVariant& value); void operator =(wxVariantData* value); void operator =(const wxString& value); void operator =(const wxChar* value); void operator =(wxChar value); void operator =(long value); void operator =(bool value); void operator =(double value); bool operator =(wxLongLong value) const; bool operator =(wxULongLong value) const; void operator =(void* value); void operator =(wxObject* value); void operator =(const wxVariantList& value); void operator =(const wxDateTime& value); void operator =(const wxArrayString& value); //@} //@{ /** Equality test operator. */ bool operator ==(const wxVariant& value) const; bool operator ==(const wxString& value) const; bool operator ==(const wxChar* value) const; bool operator ==(wxChar value) const; bool operator ==(long value) const; bool operator ==(bool value) const; bool operator ==(double value) const; bool operator ==(wxLongLong value) const; bool operator ==(wxULongLong value) const; bool operator ==(void* value) const; bool operator ==(wxObject* value) const; bool operator ==(const wxVariantList& value) const; bool operator ==(const wxArrayString& value) const; bool operator ==(const wxDateTime& value) const; //@} //@{ /** Operators for implicit conversion, using appropriate getter member function. */ double operator double() const; long operator long() const; wxLongLong operator wxLongLong() const; wxULongLong operator wxULongLong() const; //@} /** Operator for implicit conversion to a pointer to a void, using GetVoidPtr(). */ void* operator void*() const; /** Operator for implicit conversion to a wxChar, using GetChar(). */ char operator wxChar() const; /** Operator for implicit conversion to a pointer to a wxDateTime, using GetDateTime(). */ void* operator wxDateTime() const; /** Operator for implicit conversion to a string, using MakeString(). */ wxString operator wxString() const; }; /** @class wxVariantData The wxVariantData class is used to implement a new type for wxVariant. Derive from wxVariantData, and override the pure virtual functions. wxVariantData is @ref overview_refcount "reference counted", but you don't normally have to care about this, as wxVariant manages the count automatically. However, in case your application needs to take ownership of wxVariantData, be aware that the object is created with a reference count of 1, and passing it to wxVariant will not increase this. In other words, IncRef() needs to be called only if you both take ownership of wxVariantData and pass it to a wxVariant. Also note that the destructor is protected, so you can never explicitly delete a wxVariantData instance. Instead, DecRef() will delete the object automatically when the reference count reaches zero. @library{wxbase} @category{data} @see wxVariant, wxGetVariantCast() */ class wxVariantData : public wxObjectRefData { public: /** Default constructor. */ wxVariantData(); /** This function can be overridden to clone the data. You must implement this function in order for wxVariant::Unshare() to work for your data. This function is implemented for all built-in data types. */ virtual wxVariantData* Clone() const; /** Decreases reference count. If the count reaches zero, the object is automatically deleted. @note The destructor of wxVariantData is protected, so delete cannot be used as normal. Instead, DecRef() should be called. */ void DecRef(); /** Returns @true if this object is equal to @a data. */ virtual bool Eq(wxVariantData& data) const = 0; /** Converts value to wxAny, if possible. Return @true if successful. */ virtual bool GetAny(wxAny* any) const; /** Returns the string type of the data. */ virtual wxString GetType() const = 0; /** If the data is a wxObject returns a pointer to the objects wxClassInfo structure, if the data isn't a wxObject the method returns @NULL. */ virtual wxClassInfo* GetValueClassInfo(); /** Increases reference count. Note that initially wxVariantData has reference count of 1. */ void IncRef(); /** Reads the data from @a stream. */ virtual bool Read(istream& stream); /** Reads the data from @a string. */ virtual bool Read(wxString& string); /** Writes the data to @a stream. */ virtual bool Write(ostream& stream) const; /** Writes the data to @a string. */ virtual bool Write(wxString& string) const; }; // ============================================================================ // Global functions/macros // ============================================================================ /** @addtogroup group_funcmacro_rtti */ //@{ /** This macro returns a pointer to the data stored in @a var (wxVariant) cast to the type @a classname if the data is of this type (the check is done during the run-time) or @NULL otherwise. @header{wx/variant.h} @see @ref overview_rtti, wxDynamicCast() */ #define wxGetVariantCast(var, classname) //@}