Get dates directly from table in wxGridCellDateEditor if possible

Unlike wxGridCellDateRenderer, which already did it, the editor class
always got the cell value from the table as a string, even if the table
supported returning the dates directly.

Fix this by using the same code in the editor as in the renderer, which
required a further refactoring in order to make it reusable: the helper
TryParseDate() was replaced with TryGetValueAsDate() and DateParseParams
was added to allow overriding the arguments passed to it in the
overridden wxGridCellDateTimeRenderer::GetDateParseParams().

include/wx/generic/gridctrl.h

@@ -171,6 +171,8 @@ public:
 
 #include "wx/datetime.h"
 
+namespace wxGridPrivate { class DateParseParams; }
+
 // renderer for the cells containing dates only, without time component
 class WXDLLIMPEXP_ADV wxGridCellDateRenderer : public wxGridCellStringRenderer
 {
@@ -207,7 +209,11 @@ public:
 
 protected:
     wxString GetString(const wxGrid& grid, int row, int col);
-    virtual bool Parse(const wxString& text, wxDateTime& result);
+
+    // This is overridden in wxGridCellDateTimeRenderer which uses a separate
+    // input format and forbids fallback to ParseDate().
+    virtual void
+    GetDateParseParams(wxGridPrivate::DateParseParams& params) const;
 
     wxString m_oformat;
     wxDateTime::TimeZone m_tz;
@@ -229,7 +235,8 @@ public:
     virtual wxGridCellRenderer *Clone() const wxOVERRIDE;
 
 protected:
-    virtual bool Parse(const wxString& text, wxDateTime& result) wxOVERRIDE;
+    virtual void
+    GetDateParseParams(wxGridPrivate::DateParseParams& params) const wxOVERRIDE;
 
     wxString m_iformat;
 };

include/wx/generic/private/grid.h

@@ -1089,11 +1089,51 @@ namespace wxGridPrivate
 
 #if wxUSE_DATETIME
 
-// Helper function trying to parse the given string using the specified date
-// format and then using ParseDate() as a fallback if it failed. If this still
-// fails, returns false.
+// This is used as TryGetValueAsDate() parameter.
+class DateParseParams
+{
+public:
+    // Unfortunately we have to provide the default ctor (and also make the
+    // members non-const) because we use these objects as out-parameters as
+    // they are not fully declared in the public headers. The factory functions
+    // below must be used to create a really usable object.
+    DateParseParams() : fallbackParseDate(false) { }
+
+    // Use these functions to really initialize the object.
+    static DateParseParams WithFallback(const wxString& format)
+    {
+        return DateParseParams(format, true);
+    }
+
+    static DateParseParams WithoutFallback(const wxString& format)
+    {
+        return DateParseParams(format, false);
+    }
+
+    // The usual format, e.g. "%x" or "%Y-%m-%d".
+    wxString format;
+
+    // Whether fall back to ParseDate() is allowed.
+    bool fallbackParseDate;
+
+private:
+    DateParseParams(const wxString& format_, bool fallbackParseDate_)
+        : format(format_),
+          fallbackParseDate(fallbackParseDate_)
+    {
+    }
+};
+
+// Helper function trying to get a date from the given cell: if possible, get
+// the date value from the table directly, otherwise get the string value for
+// this cell and try to parse it using the specified date format and, if this
+// doesn't work and fallbackParseDate is true, try using ParseDate() as a
+// fallback. If this still fails, returns false.
 bool
-TryParseDate(wxDateTime& result, const wxString& text, const wxString& format);
+TryGetValueAsDate(wxDateTime& result,
+                  const DateParseParams& params,
+                  const wxGrid& grid,
+                  int row, int col);
 
 #endif // wxUSE_DATETIME
 

src/generic/gridctrl.cpp

@@ -77,22 +77,46 @@ void wxGridCellRenderer::Draw(wxGrid& grid,
 #if wxUSE_DATETIME
 
 bool
-wxGridPrivate::TryParseDate(wxDateTime& result,
-                            const wxString& text,
-                            const wxString& format)
+wxGridPrivate::TryGetValueAsDate(wxDateTime& result,
+                                 const DateParseParams& params,
+                                 const wxGrid& grid,
+                                 int row, int col)
 {
+    wxGridTableBase *table = grid.GetTable();
+
+    if ( table->CanGetValueAs(row, col, wxGRID_VALUE_DATETIME) )
+    {
+        void * tempval = table->GetValueAsCustom(row, col,wxGRID_VALUE_DATETIME);
+
+        if (tempval)
+        {
+            result = *((wxDateTime *)tempval);
+            delete (wxDateTime *)tempval;
+
+            return true;
+        }
+
+    }
+
+    const wxString text = table->GetValue(row, col);
+
     wxString::const_iterator end;
 
-    // Try parsing using the same format we use for output first.
-    if ( result.ParseFormat(text, format, &end) && end == text.end() )
+    if ( result.ParseFormat(text, params.format, &end) && end == text.end() )
         return true;
 
-    // But fall back to free-form parsing, which notably allows us to parse
-    // strings such as "today" or "tomorrow" which would be never accepted by
-    // ParseFormat().
-    return result.ParseDate(text, &end) && end == text.end();
+    // Check if we can fall back to free-form parsing, which notably allows us
+    // to parse strings such as "today" or "tomorrow" which would be never
+    // accepted by ParseFormat().
+    if ( params.fallbackParseDate &&
+            result.ParseDate(text, &end) && end == text.end() )
+        return true;
+
+    return false;
 }
 
+using namespace wxGridPrivate;
+
 // Enables a grid cell to display a formatted date
 
 wxGridCellDateRenderer::wxGridCellDateRenderer(const wxString& outformat)
@@ -115,40 +139,23 @@ wxGridCellRenderer *wxGridCellDateRenderer::Clone() const
 
 wxString wxGridCellDateRenderer::GetString(const wxGrid& grid, int row, int col)
 {
-    wxGridTableBase *table = grid.GetTable();
-
-    bool hasDatetime = false;
-    wxDateTime val;
     wxString text;
-    if ( table->CanGetValueAs(row, col, wxGRID_VALUE_DATETIME) )
-    {
-        void * tempval = table->GetValueAsCustom(row, col,wxGRID_VALUE_DATETIME);
 
-        if (tempval)
-        {
-            val = *((wxDateTime *)tempval);
-            hasDatetime = true;
-            delete (wxDateTime *)tempval;
-        }
+    DateParseParams params;
+    GetDateParseParams(params);
 
-    }
-
-    if (!hasDatetime )
-    {
-        text = table->GetValue(row, col);
-        hasDatetime = Parse(text, val);
-    }
-
-    if ( hasDatetime )
+    wxDateTime val;
+    if ( TryGetValueAsDate(val, params, grid, row, col) )
         text = val.Format(m_oformat, m_tz );
 
     // If we failed to parse string just show what we where given?
     return text;
 }
 
-bool wxGridCellDateRenderer::Parse(const wxString& text, wxDateTime& result)
+void
+wxGridCellDateRenderer::GetDateParseParams(DateParseParams& params) const
 {
-    return wxGridPrivate::TryParseDate(result, text, m_oformat);
+    params = DateParseParams::WithFallback(m_oformat);
 }
 
 void wxGridCellDateRenderer::Draw(wxGrid& grid,
@@ -216,10 +223,10 @@ wxGridCellRenderer *wxGridCellDateTimeRenderer::Clone() const
     return new wxGridCellDateTimeRenderer(*this);
 }
 
-bool wxGridCellDateTimeRenderer::Parse(const wxString& text, wxDateTime& result)
+void
+wxGridCellDateTimeRenderer::GetDateParseParams(DateParseParams& params) const
 {
-    const char * const end = result.ParseFormat(text, m_iformat);
-    return end && !*end;
+    params = DateParseParams::WithoutFallback(m_iformat);
 }
 
 #endif // wxUSE_DATETIME

src/generic/grideditors.cpp

@@ -1920,8 +1920,10 @@ void wxGridCellDateEditor::BeginEdit(int row, int col, wxGrid* grid)
 {
     wxASSERT_MSG(m_control, "The wxGridCellDateEditor must be created first!");
 
-    const wxString dateStr = grid->GetTable()->GetValue(row, col);
-    if ( !wxGridPrivate::TryParseDate(m_value, dateStr, m_format) )
+    using namespace wxGridPrivate;
+
+    if ( !TryGetValueAsDate(m_value, DateParseParams::WithFallback(m_format),
+                            *grid, row, col) )
     {
         // Invalidate m_value, so that it always compares different
         // to any value returned from DatePicker()->GetValue().