interface/wx/textcompleter.h

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        wx/textcompleter.h
   3 // Purpose:     interface of wxTextCompleter
   4 // Author:      Vadim Zeitlin
   5 // Created:     2011-04-13
   6 // Copyright:   (c) 2011 Vadim Zeitlin <vadim@wxwindows.org>
   7 // Licence:     wxWindows licence
   8 /////////////////////////////////////////////////////////////////////////////
   9
  10 /**
  11     @class wxTextCompleter
  12
  13     Base class for custom text completer objects.
  14
  15     Custom completer objects used with wxTextEntry::AutoComplete() must derive
  16     from this class and implement its pure virtual method returning the
  17     completions. You would typically use a custom completer when the total
  18     number of completions is too big for performance to be acceptable if all of
  19     them need to be returned at once but if they can be generated
  20     hierarchically, i.e. only the first component initially, then the second
  21     one after the user finished entering the first one and so on.
  22
  23     When inheriting from this class you need to implement its two pure virtual
  24     methods. This allows to return the results incrementally and may or not be
  25     convenient depending on where do they come from. If you prefer to return
  26     all the completions at once, you should inherit from wxTextCompleterSimple
  27     instead.
  28
  29     @since 2.9.2
  30  */
  31 class wxTextCompleter
  32 {
  33 public:
  34     /**
  35         Function called to start iteration over the completions for the given
  36         prefix.
  37
  38         This function could start a database query, for example, if the results
  39         are read from a database.
  40
  41         Notice that under some platforms (currently MSW only) it is called from
  42         another thread context and so the appropriate synchronization mechanism
  43         should be used to access any data also used by the main UI thread.
  44
  45         @param prefix
  46             The prefix for which completions are to be generated.
  47         @return
  48             @true to continue with calling GetNext() or @false to indicate that
  49             there are no matches and GetNext() shouldn't be called at all.
  50      */
  51     virtual bool Start(const wxString& prefix) = 0;
  52
  53     /**
  54         Called to retrieve the next completion.
  55
  56         All completions returned by this function should start with the prefix
  57         passed to the last call to Start().
  58
  59         Notice that, as Start(), this method is called from a worker thread
  60         context under MSW.
  61
  62         @return
  63             The next completion or an empty string to indicate that there are
  64             no more of them.
  65      */
  66     virtual wxString GetNext() = 0;
  67 };
  68
  69 /**
  70     A simpler base class for custom completer objects.
  71
  72     This class may be simpler to use than the base wxTextCompleter as it allows
  73     to implement only a single virtual method instead of two of them (at the
  74     price of storing all completions in a temporary array).
  75
  76     Here is a simple example of a custom completer that completes the names of
  77     some chess pieces. Of course, as the total list here has only four items it
  78     would have been much simpler to just specify the array containing all the
  79     completions in this example but the same approach could be used when the
  80     total number of completions is much higher provided the number of
  81     possibilities for each word is still relatively small:
  82     @code
  83     class MyTextCompleter : public wxTextCompleterSimple
  84     {
  85     public:
  86         virtual void GetCompletions(const wxString& prefix, wxArrayString& res)
  87         {
  88             const wxString firstWord = prefix.BeforeFirst(' ');
  89             if ( firstWord == "white" )
  90             {
  91                 res.push_back("white pawn");
  92                 res.push_back("white rook");
  93             }
  94             else if ( firstWord == "black" )
  95             {
  96                 res.push_back("black king");
  97                 res.push_back("black queen");
  98             }
  99             else
 100             {
 101                 res.push_back("white");
 102                 res.push_back("black");
 103             }
 104         }
 105     };
 106     ...
 107     wxTextCtrl *text = ...;
 108     text->AutoComplete(new MyTextCompleter);
 109     @endcode
 110
 111     @library{wxcore}
 112
 113     @since 2.9.2
 114 */
 115 class wxTextCompleterSimple : public wxTextCompleter
 116 {
 117 public:
 118     /**
 119         Pure virtual method returning all possible completions for the given
 120         prefix.
 121
 122         The custom completer should examine the provided prefix and return all
 123         the possible completions for it in the output array @a res.
 124
 125         Please notice that the returned values should start with the prefix,
 126         otherwise they will be simply ignored, making adding them to the array
 127         in the first place useless.
 128
 129         Notice that this function may be called from thread other than main one
 130         (this is currently always the case under MSW) so the appropriate
 131         synchronization mechanism should be used to protect the shared data.
 132
 133         @param prefix
 134             The possibly empty prefix that the user had already entered.
 135         @param res
 136             Initially empty array that should be filled with all possible
 137             completions (possibly none if there are no valid possibilities
 138             starting with the given prefix).
 139      */
 140     virtual void GetCompletions(const wxString& prefix, wxArrayString& res) = 0;
 141 };