add possibility of calculating how many rows there were before LIMIT was applied

The Finder has get_rows_counter() method which returns how many rows there were
before LIMIT clause was applied. The select(...) method should be called with
Select::with_rows_counter flag in such a case.

while here:
- change the semantic of Finder, now the select(...) method takes a morm::Select flags,
  and we have such flags:
  - Select::no_auto_generated_columns - do not generate columns from models
  - with_rows_counter - add an additional column for the rows counter
- remove Finder::prepare_to_select() - now use select(...) with no_auto_generated_columns flag

src/cursor.h

@@ -5,7 +5,7 @@
  */
 
 /*
- * Copyright (c) 2018-2021, Tomasz Sowa
+ * Copyright (c) 2018-2022, Tomasz Sowa
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -64,6 +64,8 @@ public:
 		use_table_prefix_for_fetching = c.use_table_prefix_for_fetching;
 		query_result = c.query_result;
 		select_status = c.select_status;
+		select_flags = c.select_flags;
+		rows_counter = c.rows_counter;
 
 		if( query_result )
 		{
@@ -106,6 +108,8 @@ public:
 		finder_helper.clear();
 		query_result = nullptr;
 		select_status = false;
+		select_flags = Select::default_type;
+		rows_counter = 0;
 	}
 
 
@@ -145,6 +149,18 @@ public:
 	}
 
 
+	virtual void set_select_flags(const Select & select_flags)
+	{
+		this->select_flags = select_flags;
+	}
+
+
+	virtual void set_rows_counter_column_name(const std::wstring & column_name)
+	{
+		this->rows_counter_column_name = column_name;
+	}
+
+
 	virtual QueryResult * get_query_result()
 	{
 		return query_result;
@@ -164,6 +180,23 @@ public:
 	}
 
 
+	virtual void prepare_model_env_for_new_object(ModelEnv & model_env)
+	{
+		model_env.cursor_helper = &cursor_helper;
+		model_env.finder_helper = &finder_helper;
+		model_env.select_flags = select_flags;
+		model_env.rows_counter = 0;
+
+		if( model_env.select_flags.is_with_rows_counter() )
+		{
+			if( cursor_helper.current_row == 0 )
+			{
+				model_env.rows_counter_column_name = rows_counter_column_name;
+			}
+		}
+	}
+
+
 	virtual bool get(ModelClass & result)
 	{
 		bool res = false;
@@ -177,20 +210,21 @@ public:
 
 			if( db_connector )
 			{
-				ModelEnv model_env_local;
-				result.model_env = &model_env_local;
-				result.model_env->cursor_helper = &cursor_helper;
-				result.model_env->finder_helper = &finder_helper;
-				result.model_env->model = &result;
-
 				try
 				{
+					ModelEnv model_env_local;
+					result.model_env = &model_env_local;
+					result.model_env->model = &result;
+					result.model_env->model_data = model_data;
+
 					finder_helper.clear(); // at the moment used only for calculating table prefixes (indices)
 					cursor_helper.clear();
 					cursor_helper.query_result = query_result;
 					cursor_helper.has_autogenerated_select = has_autogenerated_select;
 					cursor_helper.use_table_prefix_for_fetching_values = use_table_prefix_for_fetching;
-					result.model_env->model_data = model_data;
+					cursor_helper.current_row = 0;
+
+					prepare_model_env_for_new_object(model_env_local);
 
 					if( !cursor_helper.has_autogenerated_select && cursor_helper.use_table_prefix_for_fetching_values )
 					{
@@ -205,6 +239,7 @@ public:
 						if( query_result->cur_row < query_result->result_rows )
 						{
 							result.map_values_from_query();
+							rows_counter = model_env_local.rows_counter;
 
 							if( result.found() )
 							{
@@ -273,6 +308,7 @@ public:
 		return get_list_generic(result, clear_list);
 	}
 
+
 	virtual std::vector<ModelClass> get_vector()
 	{
 		std::vector<ModelClass> result;
@@ -282,6 +318,12 @@ public:
 	}
 
 
+	virtual size_t get_rows_counter()
+	{
+		return rows_counter;
+	}
+
+
 
 protected:
 
@@ -293,6 +335,9 @@ protected:
 	FinderHelper finder_helper; // may CursorHelper and FinderHelper should be one class?
 	QueryResult * query_result;
 	bool select_status;
+	Select select_flags;
+	size_t rows_counter;
+	std::wstring rows_counter_column_name;
 
 
 
@@ -359,15 +404,15 @@ protected:
 				cursor_helper.query_result = query_result;
 				cursor_helper.has_autogenerated_select = has_autogenerated_select;
 				cursor_helper.use_table_prefix_for_fetching_values = use_table_prefix_for_fetching;
+				cursor_helper.current_row = query_result->cur_row;
 
 				added_model.set_connector(model_connector);
 				added_model.clear();
 
+				prepare_model_env_for_new_object(model_env_local);
 				added_model.model_env = &model_env_local;
-				added_model.model_env->cursor_helper = &cursor_helper;
-				added_model.model_env->finder_helper = &finder_helper;
-				added_model.model_env->model_data = model_data;
 				added_model.model_env->model = &added_model;
+				added_model.model_env->model_data = model_data;
 
 				if( !cursor_helper.has_autogenerated_select && cursor_helper.use_table_prefix_for_fetching_values )
 				{
@@ -377,6 +422,11 @@ protected:
 				added_model.before_select();
 				added_model.map_values_from_query();
 
+				if( model_env_local.select_flags.is_with_rows_counter() && query_result->cur_row == 0 )
+				{
+					rows_counter = model_env_local.rows_counter;
+				}
+
 				if( added_model.found() )
 				{
 					added_model.after_select();