From 6e7d05d6db10b42371bfc6d88300760ed3b4d6d8 Mon Sep 17 00:00:00 2001
From: Roland Bock <rbock@eudoxos.de>
Date: Wed, 28 Aug 2024 10:44:14 +0200
Subject: [PATCH] Add type_vector::transform

plus minor refactoring
---
 include/sqlpp11/core/basic/join.h             |  4 ++++
 .../sqlpp11/core/clause/select_column_list.h  |  2 +-
 include/sqlpp11/core/detail/type_vector.h     | 21 ++++++++-----------
 include/sqlpp11/core/query/custom_query.h     |  2 +-
 include/sqlpp11/core/query/statement.h        |  4 ++--
 5 files changed, 17 insertions(+), 16 deletions(-)

diff --git a/include/sqlpp11/core/basic/join.h b/include/sqlpp11/core/basic/join.h
index a4ae1657..3b132b52 100644
--- a/include/sqlpp11/core/basic/join.h
+++ b/include/sqlpp11/core/basic/join.h
@@ -63,6 +63,10 @@ namespace sqlpp
     using type = detail::make_joined_set_t<provided_tables_of_t<Lhs>, detail::type_set<dynamic_t<Rhs>>>;
   };
 
+#warning: We need to quarantee that no tables are required by join and dynamic provision vs requirements need to be checked upon calling `on`.
+#warning: We should mix dynamic and optional into the provided_tables_of (instead of having separate traits for each).
+#warning: it might be great to search for missing tables and return something like `missing_table_for<column_t<SomeSpec>>`.
+
   template <typename Lhs, typename JoinType, typename Rhs, typename Condition>
   struct provided_optional_tables_of<join_t<Lhs, JoinType, Rhs, Condition>>
   {
diff --git a/include/sqlpp11/core/clause/select_column_list.h b/include/sqlpp11/core/clause/select_column_list.h
index 07df6a5b..6a5daf32 100644
--- a/include/sqlpp11/core/clause/select_column_list.h
+++ b/include/sqlpp11/core/clause/select_column_list.h
@@ -232,7 +232,7 @@ namespace sqlpp
   struct has_correct_aggregates<KnownAggregateColumns, select_column_list_t<Columns...>>
       : public std::integral_constant<
             bool,
-            (detail::type_vector_size<KnownAggregateColumns>::value == 0 and
+            (KnownAggregateColumns::empty() and
              logic::none<contains_aggregate_function<remove_dynamic_t<remove_as_t<Columns>>>::value...>::value) or
                 logic::all<is_aggregate_expression<KnownAggregateColumns,
                                                      remove_dynamic_t<remove_as_t<Columns>>>::value...>::value>
diff --git a/include/sqlpp11/core/detail/type_vector.h b/include/sqlpp11/core/detail/type_vector.h
index bc0ae103..9bf4d633 100644
--- a/include/sqlpp11/core/detail/type_vector.h
+++ b/include/sqlpp11/core/detail/type_vector.h
@@ -38,6 +38,15 @@ namespace sqlpp
     {
       template<typename X>
       using contains = std::integral_constant<bool, ::sqlpp::logic::any<std::is_same<T, X>::value...>::value>;
+
+      template <template <typename> class Transform>
+      using transform = type_vector<typename Transform<T>::type...>;
+
+      static constexpr bool size = sizeof...(T);
+
+      static constexpr bool empty() {
+        return size == 0;
+      }
     };
 
     template <typename... T>
@@ -73,17 +82,5 @@ namespace sqlpp
     template <typename... T>
     using type_vector_cat_t = typename type_vector_cat_impl<T...>::type;
 
-    template <typename T>
-    struct type_vector_size
-    {
-      static_assert(wrong_t<type_vector_size>::value,
-                    "type_vector_size needs to be called with a type_vector argument");
-    };
-
-    template <typename... T>
-    struct type_vector_size<type_vector<T...>>
-    {
-      static constexpr std::size_t value = sizeof...(T);
-    };
   }  // namespace detail
 }  // namespace sqlpp
diff --git a/include/sqlpp11/core/query/custom_query.h b/include/sqlpp11/core/query/custom_query.h
index d336746a..1303350d 100644
--- a/include/sqlpp11/core/query/custom_query.h
+++ b/include/sqlpp11/core/query/custom_query.h
@@ -69,7 +69,7 @@ namespace sqlpp
     using _nodes = detail::type_vector<Parts...>;
 
     using _parameter_check =
-        typename std::conditional<detail::type_vector_size<parameters_of<custom_query_t>>::value == 0,
+        typename std::conditional<parameters_of<custom_query_t>::empty(),
                                   consistent_t,
                                   assert_no_parameters_t>::type;
     using _run_check = detail::get_first_if<is_inconsistent_t, consistent_t, _parameter_check>;
diff --git a/include/sqlpp11/core/query/statement.h b/include/sqlpp11/core/query/statement.h
index cb838878..52cbd403 100644
--- a/include/sqlpp11/core/query/statement.h
+++ b/include/sqlpp11/core/query/statement.h
@@ -150,7 +150,7 @@ namespace sqlpp
       using _table_check =
           typename std::conditional<_required_tables::size::value == 0, consistent_t, assert_no_unknown_tables_t>::type;
       using _parameter_check = typename std::
-          conditional<detail::type_vector_size<_parameters>::value == 0, consistent_t, assert_no_parameters_t>::type;
+          conditional<_parameters::empty(), consistent_t, assert_no_parameters_t>::type;
     };
 
   }  // namespace detail
@@ -233,7 +233,7 @@ namespace sqlpp
 
     static constexpr size_t _get_static_no_of_parameters()
     {
-      return detail::type_vector_size<parameters_of<statement_t>>::value;
+      return parameters_of<statement_t>::size;
     }
 
     size_t _get_no_of_parameters() const