| 1 | \section{\class{wxList}}\label{wxlist} |
| 2 | |
| 3 | wxList classes provide linked list functionality for wxWidgets, and for an |
| 4 | application if it wishes. Depending on the form of constructor used, a list |
| 5 | can be keyed on integer or string keys to provide a primitive look-up ability, |
| 6 | but please note that this feature is {\bf deprecated}. |
| 7 | See \helpref{wxHashMap}{wxhashmap}\rtfsp for a faster method of storage |
| 8 | when random access is required. |
| 9 | |
| 10 | While wxList class in the previous versions of wxWidgets only could contain |
| 11 | elements of type wxObject and had essentially untyped interface (thus allowing |
| 12 | you to put apples in the list and read back oranges from it), the new wxList |
| 13 | classes family may contain elements of any type and has much more strict type |
| 14 | checking. Unfortunately, it also requires an additional line to be inserted in |
| 15 | your program for each list class you use (which is the only solution short of |
| 16 | using templates which is not done in wxWidgets because of portability issues). |
| 17 | |
| 18 | The general idea is to have the base class wxListBase working with {\it void *} |
| 19 | data but make all of its dangerous (because untyped) functions protected, so |
| 20 | that they can only be used from derived classes which, in turn, expose a type |
| 21 | safe interface. With this approach a new wxList-like class must be defined for |
| 22 | each list type (i.e. list of ints, of wxStrings or of MyObjects). This is done |
| 23 | with {\it WX\_DECLARE\_LIST} and {\it WX\_DEFINE\_LIST} macros like this |
| 24 | (notice the similarity with WX\_DECLARE\_OBJARRAY and WX\_IMPLEMENT\_OBJARRAY |
| 25 | macros): |
| 26 | |
| 27 | \wxheading{Example} |
| 28 | |
| 29 | \begin{verbatim} |
| 30 | // this part might be in a header or source (.cpp) file |
| 31 | class MyListElement |
| 32 | { |
| 33 | ... // whatever |
| 34 | }; |
| 35 | |
| 36 | // declare our list class: this macro declares and partly implements MyList |
| 37 | // class (which derives from wxListBase) |
| 38 | WX_DECLARE_LIST(MyListElement, MyList); |
| 39 | |
| 40 | ... |
| 41 | |
| 42 | // the only requirement for the rest is to be AFTER the full declaration of |
| 43 | // MyListElement (for WX_DECLARE_LIST forward declaration is enough), but |
| 44 | // usually it will be found in the source file and not in the header |
| 45 | |
| 46 | #include <wx/listimpl.cpp> |
| 47 | WX_DEFINE_LIST(MyList); |
| 48 | |
| 49 | // now MyList class may be used as a usual wxList, but all of its methods |
| 50 | // will take/return the objects of the right (i.e. MyListElement) type. You |
| 51 | // also have MyList::Node type which is the type-safe version of wxNode. |
| 52 | MyList list; |
| 53 | MyListElement element; |
| 54 | list.Append(element); // ok |
| 55 | list.Append(17); // error: incorrect type |
| 56 | |
| 57 | // let's iterate over the list |
| 58 | for ( MyList::Node *node = list.GetFirst(); node; node = node->GetNext() ) |
| 59 | { |
| 60 | MyListElement *current = node->GetData(); |
| 61 | |
| 62 | ...process the current element... |
| 63 | } |
| 64 | \end{verbatim} |
| 65 | |
| 66 | For compatibility with previous versions wxList and wxStringList classes are |
| 67 | still defined, but their usage is deprecated and they will disappear in the |
| 68 | future versions completely. The use of the latter is especially discouraged as |
| 69 | it is not only unsafe but is also much less efficient than |
| 70 | \helpref{wxArrayString}{wxarraystring} class. |
| 71 | |
| 72 | In the documentation of the list classes below, the template notations are |
| 73 | used even though these classes are not really templates at all -- but it helps |
| 74 | to think about them as if they were. You should replace wxNode<T> with |
| 75 | wxListName::Node and T itself with the list element type (i.e. the first |
| 76 | parameter of WX\_DECLARE\_LIST). |
| 77 | |
| 78 | \wxheading{Derived from} |
| 79 | |
| 80 | \helpref{wxObject}{wxobject} |
| 81 | |
| 82 | \wxheading{Include files} |
| 83 | |
| 84 | <wx/list.h> |
| 85 | |
| 86 | \wxheading{Example} |
| 87 | |
| 88 | It is very common to iterate on a list as follows: |
| 89 | |
| 90 | \begin{verbatim} |
| 91 | ... |
| 92 | wxWindow *win1 = new wxWindow(...); |
| 93 | wxWindow *win2 = new wxWindow(...); |
| 94 | |
| 95 | wxList SomeList; |
| 96 | SomeList.Append(win1); |
| 97 | SomeList.Append(win2); |
| 98 | |
| 99 | ... |
| 100 | |
| 101 | wxNode *node = SomeList.GetFirst(); |
| 102 | while (node) |
| 103 | { |
| 104 | wxWindow *win = node->GetData(); |
| 105 | ... |
| 106 | node = node->GetNext(); |
| 107 | } |
| 108 | \end{verbatim} |
| 109 | |
| 110 | To delete nodes in a list as the list is being traversed, replace |
| 111 | |
| 112 | \begin{verbatim} |
| 113 | ... |
| 114 | node = node->GetNext(); |
| 115 | ... |
| 116 | \end{verbatim} |
| 117 | |
| 118 | with |
| 119 | |
| 120 | \begin{verbatim} |
| 121 | ... |
| 122 | delete win; |
| 123 | delete node; |
| 124 | node = SomeList.GetFirst(); |
| 125 | ... |
| 126 | \end{verbatim} |
| 127 | |
| 128 | See \helpref{wxNode}{wxnode} for members that retrieve the data associated with a node, and |
| 129 | members for getting to the next or previous node. |
| 130 | |
| 131 | \wxheading{See also} |
| 132 | |
| 133 | \helpref{wxNode}{wxnode}, \helpref{wxStringList}{wxstringlist}, |
| 134 | \helpref{wxArray}{wxarray} |
| 135 | |
| 136 | \latexignore{\rtfignore{\wxheading{Members}}} |
| 137 | |
| 138 | \membersection{wxList::wxList}\label{wxlistctor} |
| 139 | |
| 140 | \func{}{wxList}{\void} |
| 141 | |
| 142 | \func{}{wxList}{\param{int}{ n}, \param{T *}{objects[]}} |
| 143 | |
| 144 | \func{}{wxList}{\param{T *}{object}, ...} |
| 145 | |
| 146 | {\bf Note}: keyed lists are deprecated and should not be used in new code. |
| 147 | |
| 148 | \func{}{wxList}{\param{unsigned int}{ key\_type}} |
| 149 | |
| 150 | Constructors. {\it key\_type} is one of wxKEY\_NONE, wxKEY\_INTEGER, or wxKEY\_STRING, |
| 151 | and indicates what sort of keying is required (if any). |
| 152 | |
| 153 | {\it objects} is an array of {\it n} objects with which to initialize the list. |
| 154 | |
| 155 | The variable-length argument list constructor must be supplied with a |
| 156 | terminating NULL. |
| 157 | |
| 158 | \membersection{wxList::\destruct{wxList}}\label{wxlistdtor} |
| 159 | |
| 160 | \func{}{\destruct{wxList}}{\void} |
| 161 | |
| 162 | Destroys the list. Also destroys any remaining nodes, but does not destroy |
| 163 | client data held in the nodes. |
| 164 | |
| 165 | \membersection{wxList::Append}\label{wxlistappend} |
| 166 | |
| 167 | \func{wxNode<T> *}{Append}{\param{T *}{object}} |
| 168 | |
| 169 | {\bf Note}: keyed lists are deprecated and should not be used in new code. |
| 170 | |
| 171 | \func{wxNode<T> *}{Append}{\param{long}{ key}, \param{T *}{object}} |
| 172 | |
| 173 | \func{wxNode<T> *}{Append}{\param{const wxString\& }{key}, \param{T *}{object}} |
| 174 | |
| 175 | Appends a new \helpref{wxNode}{wxnode} to the end of the list and puts a |
| 176 | pointer to the \rtfsp{\it object} in the node. The last two forms store a key |
| 177 | with the object for later retrieval using the key. The new node is returned in |
| 178 | each case. |
| 179 | |
| 180 | The key string is copied and stored by the list implementation. |
| 181 | |
| 182 | \membersection{wxList::Clear}\label{wxlistclear} |
| 183 | |
| 184 | \func{void}{Clear}{\void} |
| 185 | |
| 186 | Clears the list (but does not delete the client data stored with each node |
| 187 | unless you called DeleteContents({\tt true}), in which case it deletes data). |
| 188 | |
| 189 | \membersection{wxList::DeleteContents}\label{wxlistdeletecontents} |
| 190 | |
| 191 | \func{void}{DeleteContents}{\param{bool}{ destroy}} |
| 192 | |
| 193 | If {\it destroy} is {\tt true}, instructs the list to call {\it delete} on the client contents of |
| 194 | a node whenever the node is destroyed. The default is {\tt false}. |
| 195 | |
| 196 | \membersection{wxList::DeleteNode}\label{wxlistdeletenode} |
| 197 | |
| 198 | \func{bool}{DeleteNode}{\param{wxNode<T> *}{node}} |
| 199 | |
| 200 | Deletes the given node from the list, returning {\tt true} if successful. |
| 201 | |
| 202 | \membersection{wxList::DeleteObject}\label{wxlistdeleteobject} |
| 203 | |
| 204 | \func{bool}{DeleteObject}{\param{T *}{object}} |
| 205 | |
| 206 | Finds the given client {\it object} and deletes the appropriate node from the list, returning |
| 207 | {\tt true} if successful. The application must delete the actual object separately. |
| 208 | |
| 209 | \membersection{wxList::Erase}\label{wxlisterase} |
| 210 | |
| 211 | \func{void}{Erase}{\param{wxNode<T> *}{node}} |
| 212 | |
| 213 | Removes element at given position. |
| 214 | |
| 215 | \membersection{wxList::Find}\label{wxlistfind} |
| 216 | |
| 217 | \func{wxNode<T> *}{Find}{\param{T *}{ object}} |
| 218 | |
| 219 | Returns the node whose client date is {\it object} or NULL if none found. |
| 220 | |
| 221 | {\bf Note}: keyed lists are deprecated and should not be used in new code. |
| 222 | |
| 223 | \func{wxNode<T> *}{Find}{\param{long}{ key}} |
| 224 | |
| 225 | \func{wxNode<T> *}{Find}{\param{const wxString\& }{key}} |
| 226 | |
| 227 | Returns the node whose stored key matches {\it key}. Use on a keyed list only. |
| 228 | |
| 229 | \membersection{wxList::GetCount}\label{wxlistgetcount} |
| 230 | |
| 231 | \constfunc{size\_t}{GetCount}{\void} |
| 232 | |
| 233 | Returns the number of elements in the list. |
| 234 | |
| 235 | \membersection{wxList::GetFirst}\label{wxlistgetfirst} |
| 236 | |
| 237 | \func{wxNode<T> *}{GetFirst}{\void} |
| 238 | |
| 239 | Returns the first node in the list (NULL if the list is empty). |
| 240 | |
| 241 | \membersection{wxList::GetLast}\label{wxlistgetlast} |
| 242 | |
| 243 | \func{wxNode<T> *}{GetLast}{\void} |
| 244 | |
| 245 | Returns the last node in the list (NULL if the list is empty). |
| 246 | |
| 247 | \membersection{wxList::IndexOf}\label{wxlistindexof} |
| 248 | |
| 249 | \func{int}{IndexOf}{\param{T*}{ obj }} |
| 250 | |
| 251 | Returns the index of {\it obj} within the list or {\tt wxNOT\_FOUND} if {\it obj} |
| 252 | is not found in the list. |
| 253 | |
| 254 | \membersection{wxList::Insert}\label{wxlistinsert} |
| 255 | |
| 256 | \func{wxNode<T> *}{Insert}{\param{T *}{object}} |
| 257 | |
| 258 | Insert object at front of list. |
| 259 | |
| 260 | \func{wxNode<T> *}{Insert}{\param{size\_t }{position}, \param{T *}{object}} |
| 261 | |
| 262 | Insert object before {\it position}, i.e. the index of the new item in the |
| 263 | list will be equal to {\it position}. {\it position} should be less than or |
| 264 | equal to \helpref{GetCount}{wxlistgetcount}; if it is equal to it, this is the |
| 265 | same as calling \helpref{Append}{wxlistappend}. |
| 266 | |
| 267 | \func{wxNode<T> *}{Insert}{\param{wxNode<T> *}{node}, \param{T *}{object}} |
| 268 | |
| 269 | Inserts the object before the given {\it node}. |
| 270 | |
| 271 | \membersection{wxList::IsEmpty}\label{wxlistisempty} |
| 272 | |
| 273 | \constfunc{bool}{IsEmpty}{\void} |
| 274 | |
| 275 | Returns {\tt true} if the list is empty, {\tt false} otherwise. |
| 276 | |
| 277 | % Use different label name to avoid clashing with wxListItem label |
| 278 | \membersection{wxList::Item}\label{wxlistitemfunc} |
| 279 | |
| 280 | \constfunc{wxNode<T> *}{Item}{\param{size\_t }{index}} |
| 281 | |
| 282 | Returns the node at given position in the list. |
| 283 | |
| 284 | \membersection{wxList::Member}\label{wxlistmember} |
| 285 | |
| 286 | \func{wxNode<T> *}{Member}{\param{T *}{object}} |
| 287 | |
| 288 | {\bf NB:} This function is deprecated, use \helpref{Find}{wxlistfind} instead. |
| 289 | |
| 290 | Returns the node associated with {\it object} if it is in the list, NULL otherwise. |
| 291 | |
| 292 | \membersection{wxList::Nth}\label{wxlistnth} |
| 293 | |
| 294 | \func{wxNode<T> *}{Nth}{\param{int}{ n}} |
| 295 | |
| 296 | {\bf NB:} This function is deprecated, use \helpref{Item}{wxlistitemfunc} instead. |
| 297 | |
| 298 | Returns the {\it nth} node in the list, indexing from zero (NULL if the list is empty |
| 299 | or the nth node could not be found). |
| 300 | |
| 301 | \membersection{wxList::Number}\label{wxlistnumber} |
| 302 | |
| 303 | \func{int}{Number}{\void} |
| 304 | |
| 305 | {\bf NB:} This function is deprecated, use \helpref{GetCount}{wxlistgetcount} instead. |
| 306 | |
| 307 | Returns the number of elements in the list. |
| 308 | |
| 309 | \membersection{wxList::Sort}\label{wxlistsort} |
| 310 | |
| 311 | \func{void}{Sort}{\param{wxSortCompareFunction}{ compfunc}} |
| 312 | |
| 313 | \begin{verbatim} |
| 314 | // Type of compare function for list sort operation (as in 'qsort') |
| 315 | typedef int (*wxSortCompareFunction)(const void *elem1, const void *elem2); |
| 316 | \end{verbatim} |
| 317 | |
| 318 | Allows the sorting of arbitrary lists by giving |
| 319 | a function to compare two list elements. We use the system {\bf qsort} function |
| 320 | for the actual sorting process. |
| 321 | |
| 322 | If you use untyped wxList the sort function receives pointers to wxObject |
| 323 | pointers (wxObject **), so be careful to dereference appropriately - but, |
| 324 | of course, a better solution is to use list of appropriate type defined with |
| 325 | {\tt WX\_DECLARE\_LIST}. |
| 326 | |
| 327 | Example: |
| 328 | |
| 329 | \begin{verbatim} |
| 330 | int listcompare(const void *arg1, const void *arg2) |
| 331 | { |
| 332 | return(compare(**(wxString **)arg1, // use the wxString 'compare' |
| 333 | **(wxString **)arg2)); // function |
| 334 | } |
| 335 | |
| 336 | void main() |
| 337 | { |
| 338 | wxList list; |
| 339 | |
| 340 | list.Append(new wxString("DEF")); |
| 341 | list.Append(new wxString("GHI")); |
| 342 | list.Append(new wxString("ABC")); |
| 343 | list.Sort(listcompare); |
| 344 | } |
| 345 | \end{verbatim} |
| 346 | |