[glom] LayoutItem_Field: Replace predicate_LayoutItem_Field_IsSameField with function.

[Murray Cumming <murrayc src gnome org>]

commit 9da6319d0df9b5ee3119ff76826b5dcc06af3fbb
Author: Murray Cumming <murrayc murrayc com>
Date:   Mon Jul 20 22:08:24 2015 +0200

    LayoutItem_Field: Replace predicate_LayoutItem_Field_IsSameField with function.
    
    Replace with find_if_layout_item_field_is_same_field(), which uses
    a C++11 lambda.

 .../data_structure/layout/layoutitem_field.h       |   58 ++++++++++----------
 glom/libglom/utils.cc                              |    6 ++-
 glom/mode_data/box_data_details.cc                 |    2 +-
 3 files changed, 33 insertions(+), 33 deletions(-)
---
diff --git a/glom/libglom/data_structure/layout/layoutitem_field.h 
b/glom/libglom/data_structure/layout/layoutitem_field.h
index 54f5aed..cdf42fd 100644
--- a/glom/libglom/data_structure/layout/layoutitem_field.h
+++ b/glom/libglom/data_structure/layout/layoutitem_field.h
@@ -30,36 +30,6 @@
 
 namespace Glom
 {
-  
-/** A predicate for use with std::find_if() to find a LayoutItem_Field which refers 
- * to the same field, without comparing irrelevant stuff such as formatting.
- */
-template<class T_ElementField, class T_Element = T_ElementField>
-class predicate_LayoutItem_Field_IsSameField
-{
-public:
-  predicate_LayoutItem_Field_IsSameField(const std::shared_ptr<const T_ElementField>& layout_item)
-  {
-    m_layout_item = layout_item;
-  }
-
-  bool operator() (const std::shared_ptr<const T_Element>& element)
-  {
-    if(!m_layout_item && !element)
-      return true;
-
-    //Allow this to be used on a container of LayoutItems,
-    //as well as just of LayoutItem_Fields.
-    const auto element_field = std::dynamic_pointer_cast<const T_ElementField>(element);
-    if(!element_field)
-      return false;
-       
-    return m_layout_item && m_layout_item->is_same_field(element_field);
-  }
-    
-private:
-  std::shared_ptr<const T_ElementField> m_layout_item;
-};
 
 /** A LayoutItem that shows the data from a table field.
  * The field may be in a known table, or in a to table of a relationship 
@@ -189,6 +159,34 @@ private:
   std::shared_ptr<CustomTitle> m_title_custom; //translatable.
 };
 
+/**
+ * Find the element in the container which is a LayoutItem_Field which refers 
+ * to the same field, without comparing irrelevant stuff such as formatting.
+ * This assumes that the element is a shared_ptr<>.
+ */
+template
+<typename T_Container>
+auto find_if_layout_item_field_is_same_field(T_Container& container, const std::shared_ptr<const 
LayoutItem_Field>& layout_item) -> decltype(container.begin())
+{
+  return std::find_if(container.begin(), container.end(),
+    [layout_item](const typename T_Container::value_type& element)
+    {
+      //Assume that element is a shared_ptr<>.
+
+      if(!layout_item && !element)
+        return true;
+
+      //Allow this to be used on a container of LayoutItems,
+      //as well as just of LayoutItem_Fields.
+      const auto element_field = std::dynamic_pointer_cast<const LayoutItem_Field>(element);
+      if(!element_field)
+        return false;
+
+      return layout_item && layout_item->is_same_field(element_field);
+    }
+  );
+}
+
 } //namespace Glom
 
 #endif //GLOM_DATASTRUCTURE_LAYOUTITEM_FIELD_H
diff --git a/glom/libglom/utils.cc b/glom/libglom/utils.cc
index 6baf19f..84f1967 100644
--- a/glom/libglom/utils.cc
+++ b/glom/libglom/utils.cc
@@ -1510,7 +1510,8 @@ LayoutGroup::type_list_const_items Utils::get_layout_items_plus_primary_key(cons
   pk_layout_item->set_hidden();
   pk_layout_item->set_full_field_details(field_primary_key);
   
-  const LayoutGroup::type_list_const_items::const_iterator iterFind = std::find_if(items.begin(), 
items.end(), predicate_LayoutItem_Field_IsSameField<LayoutItem_Field, LayoutItem>(pk_layout_item));
+  const LayoutGroup::type_list_const_items::const_iterator iterFind =
+    find_if_layout_item_field_is_same_field(items, pk_layout_item);
   if(iterFind != items.end())
     return items; //It is already in the list:
 
@@ -1539,7 +1540,8 @@ LayoutGroup::type_list_items Utils::get_layout_items_plus_primary_key(const Layo
   pk_layout_item->set_hidden();
   pk_layout_item->set_full_field_details(field_primary_key);
   
-  const LayoutGroup::type_list_items::const_iterator iterFind = std::find_if(items.begin(), items.end(), 
predicate_LayoutItem_Field_IsSameField<LayoutItem_Field, LayoutItem>(pk_layout_item));
+  const LayoutGroup::type_list_items::const_iterator iterFind = 
+    find_if_layout_item_field_is_same_field(items, pk_layout_item);
   if(iterFind != items.end())
     return items; //It is already in the list:
 
diff --git a/glom/mode_data/box_data_details.cc b/glom/mode_data/box_data_details.cc
index 5407a39..6d521a3 100644
--- a/glom/mode_data/box_data_details.cc
+++ b/glom/mode_data/box_data_details.cc
@@ -304,7 +304,7 @@ bool Box_Data_Details::fill_from_database()
         //TODO_Performance: Do this for create_layout() only, instead of repeating it for each refresh?:
         int index_primary_key = -1; //Arbitrary default.
         //g_warning("primary_key name = %s", m_field_primary_key->get_name().c_str());
-        const auto iterFind = std::find_if(fieldsToGet.begin(), fieldsToGet.end(), 
predicate_LayoutItem_Field_IsSameField<LayoutItem_Field>(layout_item_pk));
+        const auto iterFind = find_if_layout_item_field_is_same_field(fieldsToGet, layout_item_pk);
         if(iterFind == fieldsToGet.end())
         {
           fieldsToGet.push_back(layout_item_pk);