FListBox: Import of data from a container via "lazy conversion" during item print

ChangeLog

@@ -1,3 +1,7 @@
+2017-05-19  Markus Gans  <guru.mail@muenster.de>
+	* FListBox: Import of data from a container via 
+	  "lazy conversion" during item print.
+
 2017-04-23  Markus Gans  <guru.mail@muenster.de>
 	* Import of data from a standard container in FListBox 
 	  is now possible
@@ -7,7 +11,7 @@
 2017-04-17  Markus Gans  <guru.mail@muenster.de>
 	* Speed up FString::setNumber() by using a decimal 
 	  string lookup table
-	* FString allocates no new memory if the size in sufficient
+	* FString allocates no new memory if the size is sufficient
 
 2017-04-15  Markus Gans  <guru.mail@muenster.de>
 	* Fix unsigned integer underflow in FString::_insert()

src/flistbox.cpp

@@ -7,9 +7,6 @@
 #include "fscrollbar.h"
 #include "fstatusbar.h"
 
-// function pointer
-FString& (*FListBox::getString)(FListBox::listBoxItems::iterator);
-
 
 //----------------------------------------------------------------------
 // class FListBoxItem
@@ -71,7 +68,10 @@ FListBoxItem& FListBoxItem::operator = (const FListBoxItem& item)
 //----------------------------------------------------------------------
 FListBox::FListBox (FWidget* parent)
   : FWidget(parent)
+  , convertToItem(0)
   , data()
+  , source_container(0)
+  , conv_type(FListBox::no_convert)
   , vbar(0)
   , hbar(0)
   , text()
@@ -314,8 +314,8 @@ void FListBox::insert ( const FString& item
                       , data_ptr d )
 {
   FListBoxItem listItem (item, d);
-  listItem.brackets     = b;
+  listItem.brackets = b;
-  listItem.selected     = s;
+  listItem.selected = s;
   insert (listItem);
 }
 
@@ -1459,7 +1459,7 @@ void FListBox::adjustSize()
 
 // private methods of FListBox
 //----------------------------------------------------------------------
-FString& FListBox::getString_FListBoxItem (listBoxItems::iterator iter)
+inline FString& FListBox::getString (listBoxItems::iterator iter)
 {
   return iter->getText();
 }
@@ -1505,9 +1505,6 @@ void FListBox::init()
   setLeftPadding(1);
   setBottomPadding(1);
   setRightPadding(1 + nf_offset);
-
-  // set the new getString function pointer
-  getString = &FListBox::getString_FListBoxItem;
 }
 
 //----------------------------------------------------------------------
@@ -1634,6 +1631,9 @@ void FListBox::drawList()
     bool isLineSelected = isSelected(iter);
     bool isCurrentLine = bool(y + uInt(yoffset) + 1 == uInt(current));
 
+    if ( conv_type == lazy_convert && iter->getText().isNull() )
+      convertToItem (*iter, source_container, int(y) + yoffset);
+
     if ( isLineSelected )
     {
       if ( isMonochron() )

src/flistbox.h

@@ -60,7 +60,6 @@ class FListBoxItem
    virtual FString& getText();
    virtual FWidget::data_ptr getData() const;
 
- protected:
    // Mutators
    void setText (const FString&);
    void setData (FWidget::data_ptr);
@@ -162,6 +161,8 @@ class FListBox : public FWidget
    void         hide();
    template <class Iterator, class InsertConverter>
    void         insert (Iterator, Iterator, InsertConverter);
+   template <class Container, class LazyConverter>
+   void         insert (Container, LazyConverter);
    void         insert (FListBoxItem);
    void         insert ( const FString&
                        , fc::brackets_type = fc::NoBrackets
@@ -205,6 +206,13 @@ class FListBox : public FWidget
      scrollDownSelect = 4
    };
 
+   enum convert_type
+   {
+     no_convert     = 0,
+     direct_convert = 1,
+     lazy_convert   = 2
+   };
+
    // Disable copy constructor
    FListBox (const FListBox&);
 
@@ -212,8 +220,7 @@ class FListBox : public FWidget
    FListBox& operator = (const FListBox&);
 
    // Accessors
-   static FString& getString_FListBoxItem (listBoxItems::iterator);
+   static FString& getString (listBoxItems::iterator);
-   static FString& (*getString)(listBoxItems::iterator);
 
    // Methods
    void        init();
@@ -225,8 +232,15 @@ class FListBox : public FWidget
    void        processChanged();
    listBoxItems::iterator index2iterator (int);
 
+   // Function Pointer
+   void        (*convertToItem) ( FListBoxItem&
+                                , FWidget::data_ptr
+                                , int index );
+
    // Data Members
    listBoxItems data;
+   FWidget::data_ptr source_container;
+   convert_type conv_type;
    FScrollbar*  vbar;
    FScrollbar*  hbar;
    FString      text;
@@ -257,7 +271,10 @@ inline FListBox::FListBox ( Iterator first
                           , InsertConverter convert
                           , FWidget* parent )
   : FWidget(parent)
+  , convertToItem(0)
   , data()
+  , source_container(0)
+  , conv_type(FListBox::no_convert)
   , vbar(0)
   , hbar(0)
   , text()
@@ -395,6 +412,8 @@ inline void FListBox::insert ( Iterator first
                              , Iterator last
                              , InsertConverter convert )
 {
+  conv_type = direct_convert;
+
   while ( first != last )
   {
     insert (convert(first), fc::NoBrackets, false, &(*first));
@@ -402,6 +421,19 @@ inline void FListBox::insert ( Iterator first
   }
 }
 
+//----------------------------------------------------------------------
+template <class Container, class LazyConverter>
+void FListBox::insert (Container container, LazyConverter convert)
+{
+  conv_type = lazy_convert;
+  source_container = container;
+  convertToItem = convert;
+  size_t size = container->size();
+
+  if ( size > 0 )
+    data.resize(size);
+}
+
 //----------------------------------------------------------------------
 inline FListBox::listBoxItems::iterator FListBox::index2iterator (int index)
 {

test/listbox.cpp

@@ -3,15 +3,31 @@
 #include <iostream>
 #include <fstream>
 
-#include "final.h"
+#include "fapp.h"
+#include "fdialog.h"
+#include "flistbox.h"
+#include "fmessagebox.h"
+
 
 // Global application object
 static FString* temp_str = 0;
 
 // Function prototypes
+void doubleToItem (FListBoxItem&, FWidget::data_ptr container, int index);
 FString& doubleToString (std::list<double>::const_iterator iter);
 FString& mapToString (std::map<FString, FString>::const_iterator iter);
 
+// Lazy conversion import function
+void doubleToItem (FListBoxItem& item, FWidget::data_ptr container, int index)
+{
+  typedef std::list<double>* double_list_ptr;
+  double_list_ptr dbllist = static_cast<double_list_ptr>(container);
+  std::list<double>::iterator iter = dbllist->begin();
+  std::advance (iter, index);
+  item.setText (FString().setNumber(*iter));
+  item.setData (FWidget::data_ptr(&(*iter)));
+}
+
 // Import converter functions
 FString& doubleToString (std::list<double>::const_iterator iter)
 {
@@ -50,12 +66,16 @@ class Listbox : public FDialog
 
    // Callback methods
    void cb_exitApp (FWidget*, data_ptr);
+
+   // Data Member
+   std::list<double>* double_list;
 };
 #pragma pack(pop)
 
 //----------------------------------------------------------------------
 Listbox::Listbox (FWidget* parent)
   : FDialog(parent)
+  , double_list()
 {
   temp_str = new FString;
 
@@ -72,12 +92,20 @@ Listbox::Listbox (FWidget* parent)
   list2->setGeometry(21, 1, 10, 10);
   list2->setText ("double");
 
-  std::list<double> double_list;
+  double_list = new std::list<double>;
 
   for (double i=1; i<=15; i++)
-    double_list.push_back(2*i + (i/100));
+    double_list->push_back(2*i + (i/100));
 
-  list2->insert (double_list.begin(), double_list.end(), doubleToString);
+  //
+  // Import via lazy conversion on print
+  //
+  //list2->insert (double_list, doubleToItem);
+
+  //
+  // Direct import of the complete list
+  //
+  list2->insert (double_list->begin(), double_list->end(), doubleToString);
 
   // listbox 3
   std::map<FString, FString> TLD;
@@ -109,6 +137,7 @@ Listbox::Listbox (FWidget* parent)
 Listbox::~Listbox()
 {
   delete temp_str;
+  delete double_list;
 }
 
 //----------------------------------------------------------------------