document wxLogLevel, wxTraceMask antypes and wxLogLevelValues enum

[wxWidgets.git] / interface / wx / dynarray.h

/////////////////////////////////////////////////////////////////////////////
// Name:        dynarray.h
// Purpose:     interface of wxArray<T>
// Author:      wxWidgets team
// RCS-ID:      $Id$
// Licence:     wxWindows license
/////////////////////////////////////////////////////////////////////////////

/**

    This section describes the so called @e "dynamic arrays". This is a C
    array-like type safe data structure i.e. the member access time is constant
    (and not linear according to the number of container elements as for linked
    lists). However, these arrays are dynamic in the sense that they will
    automatically allocate more memory if there is not enough of it for adding
    a new element. They also perform range checking on the index values but in
    debug mode only, so please be sure to compile your application in debug
    mode to use it (see @ref overview_debugging for details). So, unlike the
    arrays in some other languages, attempt to access an element beyond the
    arrays bound doesn't automatically expand the array but provokes an
    assertion failure instead in debug build and does nothing (except possibly
    crashing your program) in the release build.

    The array classes were designed to be reasonably efficient, both in terms
    of run-time speed and memory consumption and the executable size. The speed
    of array item access is, of course, constant (independent of the number of
    elements) making them much more efficient than linked lists (wxList).
    Adding items to the arrays is also implemented in more or less constant
    time, but the price is preallocating the memory in advance. In the
    "memory management" function section, you may find some useful hints about
    optimizing wxArray memory usage. As for executable size, all wxArray
    functions are inline, so they do not take @e any space at all.

    wxWidgets has three different kinds of array. All of them derive from
    wxBaseArray class which works with untyped data and can not be used
    directly. The standard macros WX_DEFINE_ARRAY(), WX_DEFINE_SORTED_ARRAY()
    and WX_DEFINE_OBJARRAY() are used to define a new class deriving from it.
    The classes declared will be called in this documentation wxArray,
    wxSortedArray and wxObjArray but you should keep in mind that no classes
    with such names actually exist, each time you use one of the
    WX_DEFINE_XXXARRAY() macros, you define a class with a new name. In fact,
    these names are "template" names and each usage of one of the macros
    mentioned above creates a template specialization for the given element
    type.

    wxArray is suitable for storing integer types and pointers which it does
    not treat as objects in any way, i.e. the element pointed to by the pointer
    is not deleted when the element is removed from the array. It should be
    noted that all of wxArray's functions are inline, so it costs strictly
    nothing to define as many array types as you want (either in terms of the
    executable size or the speed) as long as at least one of them is defined
    and this is always the case because wxArrays are used by wxWidgets
    internally. This class has one serious limitation: it can only be used for
    storing integral types (bool, char, short, int, long and their unsigned
    variants) or pointers (of any kind). An attempt to use with objects of
    @c sizeof() greater than @c sizeof(long) will provoke a runtime assertion
    failure, however declaring a wxArray of floats will not (on the machines
    where @c "sizeof(float) <= sizeof(long)"), yet it will @b not work, please
    use wxObjArray for storing floats and doubles.

    wxSortedArray is a wxArray variant which should be used when searching in
    the array is a frequently used operation. It requires you to define an
    additional function for comparing two elements of the array element type
    and always stores its items in the sorted order (according to this
    function). Thus, its Index() function execution time is @c "O(log(N))"
    instead of @c "O(N)" for the usual arrays but the Add() method is slower:
    it is @c "O(log(N))" instead of constant time (neglecting time spent in
    memory allocation routine). However, in a usual situation elements are
    added to an array much less often than searched inside it, so wxSortedArray
    may lead to huge performance improvements compared to wxArray. Finally, it
    should be noticed that, as wxArray, wxSortedArray can be only used for
    storing integral types or pointers.

    wxObjArray class treats its elements like "objects". It may delete them
    when they are removed from the array (invoking the correct destructor) and
    copies them using the objects copy constructor. In order to implement this
    behaviour the definition of the wxObjArray arrays is split in two parts:
    first, you should declare the new wxObjArray class using the
    WX_DECLARE_OBJARRAY() macro and then you must include the file defining the
    implementation of template type: @<wx/arrimpl.cpp@> and define the array
    class with the WX_DEFINE_OBJARRAY() macro from a point where the full (as
    opposed to 'forward') declaration of the array elements class is in scope.
    As it probably sounds very complicated here is an example:

    @code
    #include <wx/dynarray.h>

    // We must forward declare the array because it is used
    // inside the class declaration.
    class MyDirectory;
    class MyFile;

    // This defines two new types: ArrayOfDirectories and ArrayOfFiles which
    // can be now used as shown below.
    WX_DECLARE_OBJARRAY(MyDirectory, ArrayOfDirectories);
    WX_DECLARE_OBJARRAY(MyFile,      ArrayOfFiles);

    class MyDirectory
    {
        // ...
        ArrayOfDirectories m_subdirectories; // All subdirectories
        ArrayOfFiles       m_files;          // All files in this directory
    };

    // ...

    // Now that we have MyDirectory declaration in scope we may finish the
    // definition of ArrayOfDirectories -- note that this expands into some C++
    // code and so should only be compiled once (i.e., don't put this in the
    // header, but into a source file or you will get linking errors)
    #include <wx/arrimpl.cpp> // This is a magic incantation which must be done!
    WX_DEFINE_OBJARRAY(ArrayOfDirectories);

    // that's all!
    @endcode

    It is not as elegant as writing this:

    @code
    typedef std::vector<MyDirectory> ArrayOfDirectories;
    @endcode

    But is not that complicated and allows the code to be compiled with any,
    however dumb, C++ compiler in the world.

    Remember to include @<wx/arrimpl.cpp@> just before each
    WX_DEFINE_OBJARRAY() ocurrence in your code, even if you have several in
    the same file.

    Things are much simpler for wxArray and wxSortedArray however: it is enough
    just to write:

    @code
    WX_DEFINE_ARRAY_INT(int, ArrayOfInts);
    WX_DEFINE_SORTED_ARRAY_INT(int, ArrayOfSortedInts);
    @endcode

    There is only one @c DEFINE macro and no need for separate @c DECLARE one.
    For the arrays of the primitive types, the macros
    @c WX_DEFINE_ARRAY_CHAR/SHORT/INT/SIZE_T/LONG/DOUBLE should be used
    depending on the sizeof of the values (notice that storing values of
    smaller type, e.g. shorts, in an array of larger one, e.g. @c ARRAY_INT,
    does not work on all architectures!).


    @section array_macros Macros for Template Array Definition

    To use an array you must first define the array class. This is done with
    the help of the macros in this section. The class of array elements must be
    (at least) forward declared for WX_DEFINE_ARRAY(), WX_DEFINE_SORTED_ARRAY()
    and WX_DECLARE_OBJARRAY() macros and must be fully declared before you use
    WX_DEFINE_OBJARRAY() macro.

    - WX_DEFINE_ARRAY()
    - WX_DEFINE_EXPORTED_ARRAY()
    - WX_DEFINE_USER_EXPORTED_ARRAY()
    - WX_DEFINE_SORTED_ARRAY()
    - WX_DEFINE_SORTED_EXPORTED_ARRAY()
    - WX_DEFINE_SORTED_USER_EXPORTED_ARRAY()
    - WX_DECLARE_EXPORTED_OBJARRAY()
    - WX_DECLARE_USER_EXPORTED_OBJARRAY()
    - WX_DEFINE_OBJARRAY()
    - WX_DEFINE_EXPORTED_OBJARRAY()
    - WX_DEFINE_USER_EXPORTED_OBJARRAY()

    To slightly complicate the matters even further, the operator "->" defined
    by default for the array iterators by these macros only makes sense if the
    array element type is not a pointer itself and, although it still works,
    this provokes warnings from some compilers and to avoid them you should use
    the @c _PTR versions of the macros above. For example, to define an array
    of pointers to @c double you should use:

    @code
    WX_DEFINE_ARRAY_PTR(double *, MyArrayOfDoublePointers);
    @endcode

    Note that the above macros are generally only useful for wxObject types.
    There are separate macros for declaring an array of a simple type, such as
    an int.

    The following simple types are supported:
    - @c int
    - @c long
    - @c size_t
    - @c double

    To create an array of a simple type, simply append the type you want in
    CAPS to the array definition.

    For example, you'd use one of the following variants for an integer array:

    - WX_DEFINE_ARRAY_INT()
    - WX_DEFINE_EXPORTED_ARRAY_INT()
    - WX_DEFINE_USER_EXPORTED_ARRAY_INT()
    - WX_DEFINE_SORTED_ARRAY_INT()
    - WX_DEFINE_SORTED_EXPORTED_ARRAY_INT()
    - WX_DEFINE_SORTED_USER_EXPORTED_ARRAY_INT()


    @library{wxbase}
    @category{containers}

    @see @ref overview_container, wxList<T>, wxVector<T>
*/
class wxArray<T>
{
public:
    /**
        @name Constructors and Destructors

        Array classes are 100% C++ objects and as such they have the
        appropriate copy constructors and assignment operators. Copying wxArray
        just copies the elements but copying wxObjArray copies the arrays
        items. However, for memory-efficiency sake, neither of these classes
        has virtual destructor. It is not very important for wxArray which has
        trivial destructor anyhow, but it does mean that you should avoid
        deleting wxObjArray through a wxBaseArray pointer (as you would never
        use wxBaseArray anyhow it shouldn't be a problem) and that you should
        not derive your own classes from the array classes.
    */
    //@{

    /**
        Default constructor.
    */
    wxArray();

    /**
        Default constructor initializes an empty array object.
    */
    wxObjArray();

    /**
        There is no default constructor for wxSortedArray classes - you must
        initialize it with a function to use for item comparison. It is a
        function which is passed two arguments of type @c T where @c T is the
        array element type and which should return a negative, zero or positive
        value according to whether the first element passed to it is less than,
        equal to or greater than the second one.
    */
    wxSortedArray(int (*)(T first, T second)compareFunction);

    /**
        Performs a shallow array copy (i.e. doesn't copy the objects pointed to
        even if the source array contains the items of pointer type).
    */
    wxArray(const wxArray& array);

    /**
        Performs a shallow array copy (i.e. doesn't copy the objects pointed to
        even if the source array contains the items of pointer type).
    */
    wxSortedArray(const wxSortedArray& array);

    /**
        Performs a deep copy (i.e. the array element are copied too).
    */
    wxObjArray(const wxObjArray& array);

    /**
        Performs a shallow array copy (i.e. doesn't copy the objects pointed to
        even if the source array contains the items of pointer type).
    */
    wxArray& operator=(const wxArray& array);

    /**
        Performs a shallow array copy (i.e. doesn't copy the objects pointed to
        even if the source array contains the items of pointer type).
    */
    wxSortedArray& operator=(const wxSortedArray& array);

    /**
        Performs a deep copy (i.e. the array element are copied too).
    */
    wxObjArray& operator=(const wxObjArray& array);

    /**
        This destructor does not delete all the items owned by the array, you
        may use the WX_CLEAR_ARRAY() macro for this.
    */
    ~wxArray();

    /**
        This destructor does not delete all the items owned by the array, you
        may use the WX_CLEAR_ARRAY() macro for this.
    */
    ~wxSortedArray();

    /**
        This destructor deletes all the items owned by the array.
    */
    ~wxObjArray();

    //@}


    /**
        @name Memory Management

        Automatic array memory management is quite trivial: the array starts by
        preallocating some minimal amount of memory (defined by
        @c WX_ARRAY_DEFAULT_INITIAL_SIZE) and when further new items exhaust
        already allocated memory it reallocates it adding 50% of the currently
        allocated amount, but no more than some maximal number which is defined
        by the @c ARRAY_MAXSIZE_INCREMENT constant. Of course, this may lead to
        some memory being wasted (@c ARRAY_MAXSIZE_INCREMENT in the worst case,
        i.e. 4Kb in the current implementation), so the Shrink() function is
        provided to deallocate the extra memory. The Alloc() function can also
        be quite useful if you know in advance how many items you are going to
        put in the array and will prevent the array code from reallocating the
        memory more times than needed.
    */
    //@{

    /**
        Preallocates memory for a given number of array elements. It is worth
        calling when the number of items which are going to be added to the
        array is known in advance because it will save unneeded memory
        reallocation. If the array already has enough memory for the given
        number of items, nothing happens. In any case, the existing contents of
        the array is not modified.
    */
    void Alloc(size_t count);

    /**
        Frees all memory unused by the array. If the program knows that no new
        items will be added to the array it may call Shrink() to reduce its
        memory usage. However, if a new item is added to the array, some extra
        memory will be allocated again.
    */
    void Shrink();

    //@}


    /**
        @name Number of Elements and Simple Item Access

        Functions in this section return the total number of array elements and
        allow to retrieve them - possibly using just the C array indexing []
        operator which does exactly the same as the Item() method.
    */
    //@{

    /**
        Return the number of items in the array.
    */
    size_t GetCount() const;

    /**
        Returns @true if the array is empty, @false otherwise.
    */
    bool IsEmpty() const;

    /**
        Returns the item at the given position in the array. If @a index is out
        of bounds, an assert failure is raised in the debug builds but nothing
        special is done in the release build.

        The returned value is of type "reference to the array element type" for
        all of the array classes.
    */
    T& Item(size_t index) const;

    /**
        Returns the last element in the array, i.e. is the same as calling
        "Item(GetCount() - 1)". An assert failure is raised in the debug mode
        if the array is empty.

        The returned value is of type "reference to the array element type" for
        all of the array classes.
    */
    T& Last() const;

    //@}


    /**
        @name Adding Items
    */
    //@{

    /**
        Appends the given number of @a copies of the @a item to the array
        consisting of the elements of type @c T.

        This version is used with wxArray.

        You may also use WX_APPEND_ARRAY() macro to append all elements of one
        array to another one but it is more efficient to use the @a copies
        parameter and modify the elements in place later if you plan to append
        a lot of items.
    */
    void Add(T item, size_t copies = 1);

    /**
        Appends the @a item to the array consisting of the elements of type
        @c T.

        This version is used with wxSortedArray, returning the index where
        @a item is stored.
    */
    size_t Add(T item);

    /**
        Appends the @a item to the array consisting of the elements of type
        @c T.

        This version is used with wxObjArray. The array will take ownership of
        the @a item, deleting it when the item is deleted from the array. Note
        that you cannot append more than one pointer as reusing it would lead
        to deleting it twice (or more) resulting in a crash.

        You may also use WX_APPEND_ARRAY() macro to append all elements of one
        array to another one but it is more efficient to use the @a copies
        parameter and modify the elements in place later if you plan to append
        a lot of items.
    */
    void Add(T* item);

    /**
        Appends the given number of @a copies of the @a item to the array
        consisting of the elements of type @c T.

        This version is used with wxObjArray. The array will make a copy of the
        item and will not take ownership of the original item.

        You may also use WX_APPEND_ARRAY() macro to append all elements of one
        array to another one but it is more efficient to use the @a copies
        parameter and modify the elements in place later if you plan to append
        a lot of items.
    */
    void Add(T& item, size_t copies = 1);

    /**
        Inserts the given @a item into the array in the specified @e index
        position.

        Be aware that you will set out the order of the array if you give a
        wrong position.

        This function is useful in conjunction with IndexForInsert() for a
        common operation of "insert only if not found".
    */
    void AddAt(T item, size_t index);

    /**
        Insert the given number of @a copies of the @a item into the array
        before the existing item @a n - thus, @e Insert(something, 0u) will
        insert an item in such way that it will become the first array element.

        wxSortedArray doesn't have this function because inserting in wrong
        place would break its sorted condition.

        Please see Add() for an explanation of the differences between the
        overloaded versions of this function.
    */
    void Insert(T item, size_t n, size_t copies = 1);

    /**
        Insert the @a item into the array before the existing item @a n - thus,
        @e Insert(something, 0u) will insert an item in such way that it will
        become the first array element.

        wxSortedArray doesn't have this function because inserting in wrong
        place would break its sorted condition.

        Please see Add() for an explanation of the differences between the
        overloaded versions of this function.
    */
    void Insert(T* item, size_t n);

    /**
        Insert the given number of @a copies of the @a item into the array
        before the existing item @a n - thus, @e Insert(something, 0u) will
        insert an item in such way that it will become the first array element.

        wxSortedArray doesn't have this function because inserting in wrong
        place would break its sorted condition.

        Please see Add() for an explanation of the differences between the
        overloaded versions of this function.
    */
    void Insert(T& item, size_t n, size_t copies = 1);

    /**
        This function ensures that the number of array elements is at least
        @a count. If the array has already @a count or more items, nothing is
        done. Otherwise, @a count - GetCount() elements are added and
        initialized to the value @a defval.

        @see GetCount()
    */
    void SetCount(size_t count, T defval = T(0));

    //@}


    /**
        @name Removing Items
    */
    //@{

    /**
        This function does the same as Empty() and additionally frees the
        memory allocated to the array.
    */
    void Clear();

    /**
        Removes the element from the array, but unlike Remove(), it doesn't
        delete it. The function returns the pointer to the removed element.
    */
    T* Detach(size_t index);

    /**
        Empties the array. For wxObjArray classes, this destroys all of the
        array elements. For wxArray and wxSortedArray this does nothing except
        marking the array of being empty - this function does not free the
        allocated memory, use Clear() for this.
    */
    void Empty();

    /**
        Removes an element from the array by value: the first item of the array
        equal to @a item is removed, an assert failure will result from an
        attempt to remove an item which doesn't exist in the array.

        When an element is removed from wxObjArray it is deleted by the array -
        use Detach() if you don't want this to happen. On the other hand, when
        an object is removed from a wxArray nothing happens - you should delete
        it manually if required:

        @code
        T *item = array[n];
        delete item;
        array.Remove(n);
        @endcode

        See also WX_CLEAR_ARRAY() macro which deletes all elements of a wxArray
        (supposed to contain pointers).
    */
    Remove(T item);

    /**
        Removes @a count elements starting at @a index from the array. When an
        element is removed from wxObjArray it is deleted by the array - use
        Detach() if you don't want this to happen. On the other hand, when an
        object is removed from a wxArray nothing happens - you should delete it
        manually if required:

        @code
        T *item = array[n];
        delete item;
        array.RemoveAt(n);
        @endcode

        See also WX_CLEAR_ARRAY() macro which deletes all elements of a wxArray
        (supposed to contain pointers).
    */
    RemoveAt(size_t index, size_t count = 1);

    //@}


    /**
        @name Searching and Sorting
    */
    //@{

    /**
        This version of Index() is for wxArray and wxObjArray only.

        Searches the element in the array, starting from either beginning or
        the end depending on the value of @a searchFromEnd parameter.
        @c wxNOT_FOUND is returned if the element is not found, otherwise the
        index of the element is returned.

        @note Even for wxObjArray classes, the operator "==" of the elements in
              the array is @b not used by this function. It searches exactly
              the given element in the array and so will only succeed if this
              element had been previously added to the array, but fail even if
              another, identical, element is in the array.
    */
    int Index(T& item, bool searchFromEnd = false) const;
    /**
        This version of Index() is for wxSortedArray only.

        Searches the element in the array, starting from either beginning or
        the end depending on the value of @a searchFromEnd parameter.
        @c wxNOT_FOUND is returned if the element is not found, otherwise the
        index of the element is returned.
    */
    const int Index(T& item) const;

    /**
        Search for a place to insert @a item into the sorted array (binary
        search). The index returned is just before the first existing item that
        is greater or equal (according to the compare function) to the given
        @a item.

        You have to do extra work to know if the @a item already exists in
        array.

        This function is useful in conjunction with AddAt() for a common
        operation of "insert only if not found".
    */
    size_t IndexForInsert(T item) const;

    /**
        The notation @c "CMPFUNCT<T>" should be read as if we had the following
        declaration:

        @code
        template int CMPFUNC(T *first, T *second);
        @endcode

        Where @e T is the type of the array elements. I.e. it is a function
        returning @e int which is passed two arguments of type @e T*.

        Sorts the array using the specified compare function: this function
        should return a negative, zero or positive value according to whether
        the first element passed to it is less than, equal to or greater than
        the second one.

        wxSortedArray doesn't have this function because it is always sorted.
    */
    void Sort(CMPFUNC<T> compareFunction);

    //@}
};


/**
    This macro may be used to append all elements of the @a wxArray_arrayToBeAppended
    array to the @a wxArray_arrayToModify. The two arrays must be of the same type.
*/
#define WX_APPEND_ARRAY(wxArray_arrayToModify, wxArray_arrayToBeAppended)

/**
    This macro may be used to delete all elements of the array before emptying
    it. It can not be used with wxObjArrays - but they will delete their
    elements anyway when you call Empty().
*/
#define WX_CLEAR_ARRAY(wxArray_arrayToBeCleared)

//@{
/**
    This macro declares a new object array class named @a name and containing
    the elements of type @e T.

    An exported array is used when compiling wxWidgets as a DLL under Windows
    and the array needs to be visible outside the DLL. An user exported array
    needed for exporting an array from a user DLL.

    Example:

    @code
    class MyClass;
    WX_DECLARE_OBJARRAY(MyClass, wxArrayOfMyClass); // note: not "MyClass *"!
    @endcode

    You must use WX_DEFINE_OBJARRAY() macro to define the array class,
    otherwise you would get link errors.
*/
#define WX_DECLARE_OBJARRAY(T, name)
#define WX_DECLARE_EXPORTED_OBJARRAY(T, name)
#define WX_DECLARE_USER_EXPORTED_OBJARRAY(T, name)
//@}

//@{
/**
    This macro defines a new array class named @a name and containing the
    elements of type @a T.

    An exported array is used when compiling wxWidgets as a DLL under Windows
    and the array needs to be visible outside the DLL. An user exported array
    needed for exporting an array from a user DLL.

    Example:

    @code
    WX_DEFINE_ARRAY_INT(int, MyArrayInt);

    class MyClass;
    WX_DEFINE_ARRAY(MyClass *, ArrayOfMyClass);
    @endcode

    Note that wxWidgets predefines the following standard array classes:
    @b wxArrayInt, @b wxArrayLong, @b wxArrayShort, @b wxArrayDouble,
    @b wxArrayPtrVoid.
*/
#define WX_DEFINE_ARRAY(T, name)
#define WX_DEFINE_EXPORTED_ARRAY(T, name)
#define WX_DEFINE_USER_EXPORTED_ARRAY(T, name, exportspec)
//@}

//@{
/**
    This macro defines the methods of the array class @a name not defined by
    the WX_DECLARE_OBJARRAY() macro. You must include the file
    @<wx/arrimpl.cpp@> before using this macro and you must have the full
    declaration of the class of array elements in scope! If you forget to do
    the first, the error will be caught by the compiler, but, unfortunately,
    many compilers will not give any warnings if you forget to do the second -
    but the objects of the class will not be copied correctly and their real
    destructor will not be called.

    An exported array is used when compiling wxWidgets as a DLL under Windows
    and the array needs to be visible outside the DLL. An user exported array
    needed for exporting an array from a user DLL.

    Example of usage:

    @code
    // first declare the class!
    class MyClass
    {
    public:
        MyClass(const MyClass&);

        // ...

        virtual ~MyClass();
    };

    #include <wx/arrimpl.cpp>
    WX_DEFINE_OBJARRAY(wxArrayOfMyClass);
    @endcode
*/
#define WX_DEFINE_OBJARRAY(name)
#define WX_DEFINE_EXPORTED_OBJARRAY(name)
#define WX_DEFINE_USER_EXPORTED_OBJARRAY(name)
//@}

//@{
/**
    This macro defines a new sorted array class named @a name and containing
    the elements of type @e T.

    An exported array is used when compiling wxWidgets as a DLL under Windows
    and the array needs to be visible outside the DLL. An user exported array
    needed for exporting an array from a user DLL.

    Example:

    @code
    WX_DEFINE_SORTED_ARRAY_INT(int, MySortedArrayInt);

    class MyClass;
    WX_DEFINE_SORTED_ARRAY(MyClass *, ArrayOfMyClass);
    @endcode

    You will have to initialize the objects of this class by passing a
    comparison function to the array object constructor like this:

    @code
    int CompareInts(int n1, int n2)
    {
        return n1 - n2;
    }

    MySortedArrayInt sorted(CompareInts);

    int CompareMyClassObjects(MyClass *item1, MyClass *item2)
    {
        // sort the items by their address...
        return Stricmp(item1->GetAddress(), item2->GetAddress());
    }

    ArrayOfMyClass another(CompareMyClassObjects);
    @endcode
*/
#define WX_DEFINE_SORTED_ARRAY(T, name)
#define WX_DEFINE_SORTED_EXPORTED_ARRAY(T, name)
#define WX_DEFINE_SORTED_USER_EXPORTED_ARRAY(T, name)
//@}

/**
    This macro may be used to prepend all elements of the @a wxArray_arrayToBePrepended
    array to the @a wxArray_arrayToModify. The two arrays must be of the same type.
*/
#define WX_PREPEND_ARRAY(wxArray_arrayToModify, wxArray_arrayToBePrepended)