From b9eca7db178c3eb5645f818f1bd71d9b4c440cd5 Mon Sep 17 00:00:00 2001
From: Roland Bock <rbock@eudoxos.de>
Date: Tue, 30 Jul 2024 06:45:00 +0200
Subject: [PATCH] More moves

And introduced sqlpp::enable_if_t
---
 include/sqlpp11/core/aggregate_function/avg.h |  6 +--
 .../sqlpp11/core/aggregate_function/count.h   |  6 +--
 .../{ => aggregate_function}/enable_over.h    |  0
 include/sqlpp11/core/aggregate_function/max.h |  6 +--
 include/sqlpp11/core/aggregate_function/min.h |  6 +--
 .../sqlpp11/core/aggregate_function/over.h    |  6 +--
 include/sqlpp11/core/aggregate_function/sum.h |  6 +--
 include/sqlpp11/core/basic/column.h           |  4 +-
 .../sqlpp11/core/{ => basic}/enable_join.h    |  0
 include/sqlpp11/core/basic/parameter.h        |  2 +-
 include/sqlpp11/core/basic/table.h            |  2 +-
 include/sqlpp11/core/basic/table_alias.h      |  2 +-
 include/sqlpp11/core/basic/value.h            |  2 +-
 include/sqlpp11/core/basic/verbatim_table.h   |  2 +-
 .../sqlpp11/core/clause/insert_value_list.h   |  2 +-
 include/sqlpp11/core/clause/select_as.h       |  4 +-
 .../sqlpp11/core/{ => clause}/simple_column.h |  0
 .../sqlpp11/core/{ => clause}/single_table.h  |  0
 include/sqlpp11/core/clause/update.h          |  2 +-
 include/sqlpp11/core/compat/make_unique.h     | 24 ++++++---
 include/sqlpp11/core/compat/type_traits.h     | 51 +++++++++++++++++++
 include/sqlpp11/core/function/lower.h         |  2 +-
 include/sqlpp11/core/function/trim.h          |  2 +-
 include/sqlpp11/core/function/upper.h         |  2 +-
 include/sqlpp11/core/operator/any.h           |  2 +-
 .../core/operator/arithmetic_expression.h     | 10 ++--
 include/sqlpp11/core/operator/as_expression.h |  2 +-
 .../sqlpp11/core/operator/assign_expression.h |  4 +-
 .../core/operator/between_expression.h        |  6 +--
 .../sqlpp11/core/operator/bit_expression.h    |  4 +-
 .../core/operator/comparison_expression.h     |  6 +--
 .../sqlpp11/core/{ => operator}/enable_as.h   |  0
 .../core/{ => operator}/enable_comparison.h   |  0
 .../sqlpp11/core/operator/exists_expression.h |  4 +-
 include/sqlpp11/core/operator/in_expression.h |  4 +-
 .../core/operator/logical_expression.h        |  4 +-
 .../core/operator/sort_order_expression.h     |  2 +-
 include/sqlpp11/core/query/dynamic.h          |  4 +-
 include/sqlpp11/core/type_traits.h            |  1 +
 39 files changed, 126 insertions(+), 66 deletions(-)
 rename include/sqlpp11/core/{ => aggregate_function}/enable_over.h (100%)
 rename include/sqlpp11/core/{ => basic}/enable_join.h (100%)
 rename include/sqlpp11/core/{ => clause}/simple_column.h (100%)
 rename include/sqlpp11/core/{ => clause}/single_table.h (100%)
 create mode 100644 include/sqlpp11/core/compat/type_traits.h
 rename include/sqlpp11/core/{ => operator}/enable_as.h (100%)
 rename include/sqlpp11/core/{ => operator}/enable_comparison.h (100%)

diff --git a/include/sqlpp11/core/aggregate_function/avg.h b/include/sqlpp11/core/aggregate_function/avg.h
index 48265038..f1a8893a 100644
--- a/include/sqlpp11/core/aggregate_function/avg.h
+++ b/include/sqlpp11/core/aggregate_function/avg.h
@@ -26,8 +26,8 @@
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include <sqlpp11/core/enable_as.h>
-#include <sqlpp11/core/enable_over.h>
+#include <sqlpp11/core/operator/enable_as.h>
+#include <sqlpp11/core/aggregate_function/enable_over.h>
 #include <sqlpp11/core/type_traits.h>
 
 namespace sqlpp
@@ -74,7 +74,7 @@ namespace sqlpp
 
   template <typename T>
   using check_avg_arg =
-      std::enable_if_t<(is_numeric<T>::value or is_boolean<T>::value) and not contains_aggregate_function_t<T>::value>;
+      ::sqlpp::enable_if_t<(is_numeric<T>::value or is_boolean<T>::value) and not contains_aggregate_function_t<T>::value>;
 
   template <typename T, typename = check_avg_arg<T>>
   auto avg(T t) -> avg_t<noop, T>
diff --git a/include/sqlpp11/core/aggregate_function/count.h b/include/sqlpp11/core/aggregate_function/count.h
index bfa7832b..40c22131 100644
--- a/include/sqlpp11/core/aggregate_function/count.h
+++ b/include/sqlpp11/core/aggregate_function/count.h
@@ -26,8 +26,8 @@
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include <sqlpp11/core/enable_as.h>
-#include <sqlpp11/core/enable_over.h>
+#include <sqlpp11/core/operator/enable_as.h>
+#include <sqlpp11/core/aggregate_function/enable_over.h>
 #include <sqlpp11/core/clause/select_flags.h>
 #include <sqlpp11/core/type_traits.h>
 
@@ -77,7 +77,7 @@ namespace sqlpp
 
   template <typename T>
   using check_count_arg =
-      std::enable_if_t<values_are_comparable<T, T>::value and not contains_aggregate_function_t<T>::value>;
+      ::sqlpp::enable_if_t<values_are_comparable<T, T>::value and not contains_aggregate_function_t<T>::value>;
 
   template <typename T, typename = check_count_arg<T>>
   auto count(T t) -> count_t<noop, T>
diff --git a/include/sqlpp11/core/enable_over.h b/include/sqlpp11/core/aggregate_function/enable_over.h
similarity index 100%
rename from include/sqlpp11/core/enable_over.h
rename to include/sqlpp11/core/aggregate_function/enable_over.h
diff --git a/include/sqlpp11/core/aggregate_function/max.h b/include/sqlpp11/core/aggregate_function/max.h
index f440a93a..dd43acc1 100644
--- a/include/sqlpp11/core/aggregate_function/max.h
+++ b/include/sqlpp11/core/aggregate_function/max.h
@@ -26,8 +26,8 @@
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include <sqlpp11/core/enable_as.h>
-#include <sqlpp11/core/enable_over.h>
+#include <sqlpp11/core/operator/enable_as.h>
+#include <sqlpp11/core/aggregate_function/enable_over.h>
 #include <sqlpp11/core/clause/select_flags.h>
 #include <sqlpp11/core/type_traits.h>
 
@@ -76,7 +76,7 @@ namespace sqlpp
 
   template <typename T>
   using check_max_arg =
-      std::enable_if_t<values_are_comparable<T, T>::value and not contains_aggregate_function_t<T>::value>;
+      ::sqlpp::enable_if_t<values_are_comparable<T, T>::value and not contains_aggregate_function_t<T>::value>;
 
   template <typename T, typename = check_max_arg<T>>
   auto max(T t) -> max_t<noop, T>
diff --git a/include/sqlpp11/core/aggregate_function/min.h b/include/sqlpp11/core/aggregate_function/min.h
index eaba8908..a1f983e3 100644
--- a/include/sqlpp11/core/aggregate_function/min.h
+++ b/include/sqlpp11/core/aggregate_function/min.h
@@ -26,8 +26,8 @@
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include <sqlpp11/core/enable_as.h>
-#include <sqlpp11/core/enable_over.h>
+#include <sqlpp11/core/operator/enable_as.h>
+#include <sqlpp11/core/aggregate_function/enable_over.h>
 #include <sqlpp11/core/clause/select_flags.h>
 #include <sqlpp11/core/type_traits.h>
 
@@ -76,7 +76,7 @@ namespace sqlpp
 
   template <typename T>
   using check_min_arg =
-      std::enable_if_t<values_are_comparable<T, T>::value and not contains_aggregate_function_t<T>::value>;
+      ::sqlpp::enable_if_t<values_are_comparable<T, T>::value and not contains_aggregate_function_t<T>::value>;
 
   template <typename T, typename = check_min_arg<T>>
   auto min(T t) -> min_t<noop, T>
diff --git a/include/sqlpp11/core/aggregate_function/over.h b/include/sqlpp11/core/aggregate_function/over.h
index 42a1bff0..0a6ab11d 100644
--- a/include/sqlpp11/core/aggregate_function/over.h
+++ b/include/sqlpp11/core/aggregate_function/over.h
@@ -26,8 +26,8 @@
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include <sqlpp11/core/enable_as.h>
-#include <sqlpp11/core/enable_comparison.h>
+#include <sqlpp11/core/operator/enable_as.h>
+#include <sqlpp11/core/operator/enable_comparison.h>
 #include <sqlpp11/core/type_traits.h>
 
 namespace sqlpp
@@ -59,7 +59,7 @@ namespace sqlpp
   struct nodes_of<over_t<Expr>>: public nodes_of<Expr> {};
 
   template<typename Expr>
-  using check_over_args = std::enable_if_t<contains_aggregate_function_t<Expr>::value>;
+  using check_over_args = ::sqlpp::enable_if_t<contains_aggregate_function_t<Expr>::value>;
 
   template <typename Context, typename Expr>
   Context& serialize(Context& context, const over_t<Expr>& t)
diff --git a/include/sqlpp11/core/aggregate_function/sum.h b/include/sqlpp11/core/aggregate_function/sum.h
index decc1c1c..392f8c1b 100644
--- a/include/sqlpp11/core/aggregate_function/sum.h
+++ b/include/sqlpp11/core/aggregate_function/sum.h
@@ -26,8 +26,8 @@
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include <sqlpp11/core/enable_as.h>
-#include <sqlpp11/core/enable_over.h>
+#include <sqlpp11/core/operator/enable_as.h>
+#include <sqlpp11/core/aggregate_function/enable_over.h>
 #include <sqlpp11/core/clause/select_flags.h>
 #include <sqlpp11/core/type_traits.h>
 
@@ -77,7 +77,7 @@ namespace sqlpp
 
   template <typename T>
   using check_sum_arg =
-      std::enable_if_t<(is_numeric<T>::value or is_boolean<T>::value) and not contains_aggregate_function_t<T>::value>;
+      ::sqlpp::enable_if_t<(is_numeric<T>::value or is_boolean<T>::value) and not contains_aggregate_function_t<T>::value>;
 
   template <typename T, typename = check_sum_arg<T>>
   auto sum(T t) -> sum_t<noop, T>
diff --git a/include/sqlpp11/core/basic/column.h b/include/sqlpp11/core/basic/column.h
index 1f48ce9c..7a71f270 100644
--- a/include/sqlpp11/core/basic/column.h
+++ b/include/sqlpp11/core/basic/column.h
@@ -26,8 +26,8 @@
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include <sqlpp11/core/enable_as.h>
-#include <sqlpp11/core/enable_comparison.h>
+#include <sqlpp11/core/operator/enable_as.h>
+#include <sqlpp11/core/operator/enable_comparison.h>
 #include <sqlpp11/core/operator/as_expression.h>
 #include <sqlpp11/core/operator/assign_expression.h>
 #include <sqlpp11/core/basic/column_fwd.h>
diff --git a/include/sqlpp11/core/enable_join.h b/include/sqlpp11/core/basic/enable_join.h
similarity index 100%
rename from include/sqlpp11/core/enable_join.h
rename to include/sqlpp11/core/basic/enable_join.h
diff --git a/include/sqlpp11/core/basic/parameter.h b/include/sqlpp11/core/basic/parameter.h
index 6948644a..d3263d92 100644
--- a/include/sqlpp11/core/basic/parameter.h
+++ b/include/sqlpp11/core/basic/parameter.h
@@ -26,7 +26,7 @@
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include <sqlpp11/core/enable_comparison.h>
+#include <sqlpp11/core/operator/enable_comparison.h>
 #include <sqlpp11/core/type_traits.h>
 #include <sqlpp11/core/alias_provider.h>
 #include <sqlpp11/core/detail/type_set.h>
diff --git a/include/sqlpp11/core/basic/table.h b/include/sqlpp11/core/basic/table.h
index 11f29d68..456447ea 100644
--- a/include/sqlpp11/core/basic/table.h
+++ b/include/sqlpp11/core/basic/table.h
@@ -26,7 +26,7 @@
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include <sqlpp11/core/enable_join.h>
+#include <sqlpp11/core/basic/enable_join.h>
 #include <sqlpp11/core/type_traits.h>
 #include <sqlpp11/core/basic/table_alias.h>
 #include <sqlpp11/core/basic/all_of.h>
diff --git a/include/sqlpp11/core/basic/table_alias.h b/include/sqlpp11/core/basic/table_alias.h
index 57b64c3d..b31e9a2b 100644
--- a/include/sqlpp11/core/basic/table_alias.h
+++ b/include/sqlpp11/core/basic/table_alias.h
@@ -26,7 +26,7 @@
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include <sqlpp11/core/enable_join.h>
+#include <sqlpp11/core/basic/enable_join.h>
 #include <sqlpp11/core/basic/table_columns.h>
 #include <sqlpp11/core/detail/type_set.h>
 #include <sqlpp11/core/serialize.h>
diff --git a/include/sqlpp11/core/basic/value.h b/include/sqlpp11/core/basic/value.h
index 47cd6662..7ed5153a 100644
--- a/include/sqlpp11/core/basic/value.h
+++ b/include/sqlpp11/core/basic/value.h
@@ -50,7 +50,7 @@ namespace sqlpp
   };
 
   template <typename T>
-  using check_value_arg = std::enable_if_t<not std::is_same<value_type_of_t<T>, no_value_t>::value and values_are_comparable<T, T>::value>;
+  using check_value_arg = ::sqlpp::enable_if_t<not std::is_same<value_type_of_t<T>, no_value_t>::value and values_are_comparable<T, T>::value>;
 
   template <typename Context, typename T>
   Context& serialize(Context& context, const value_t<T>& t)
diff --git a/include/sqlpp11/core/basic/verbatim_table.h b/include/sqlpp11/core/basic/verbatim_table.h
index 002cc282..d2f22db3 100644
--- a/include/sqlpp11/core/basic/verbatim_table.h
+++ b/include/sqlpp11/core/basic/verbatim_table.h
@@ -28,7 +28,7 @@
 
 #include <utility>
 
-#include <sqlpp11/core/enable_join.h>
+#include <sqlpp11/core/basic/enable_join.h>
 #include <sqlpp11/core/type_traits.h>
 
 namespace sqlpp
diff --git a/include/sqlpp11/core/clause/insert_value_list.h b/include/sqlpp11/core/clause/insert_value_list.h
index 15e676d0..764abbf5 100644
--- a/include/sqlpp11/core/clause/insert_value_list.h
+++ b/include/sqlpp11/core/clause/insert_value_list.h
@@ -34,7 +34,7 @@
 #include <sqlpp11/core/no_data.h>
 #include <sqlpp11/core/query/policy_update.h>
 #include <sqlpp11/core/portable_static_assert.h>
-#include <sqlpp11/core/simple_column.h>
+#include <sqlpp11/core/clause/simple_column.h>
 #include <sqlpp11/core/query/statement.h>
 #include <sqlpp11/core/type_traits.h>
 
diff --git a/include/sqlpp11/core/clause/select_as.h b/include/sqlpp11/core/clause/select_as.h
index e4714497..b8293289 100644
--- a/include/sqlpp11/core/clause/select_as.h
+++ b/include/sqlpp11/core/clause/select_as.h
@@ -27,8 +27,8 @@
  */
 
 #include <sqlpp11/core/type_traits.h>
-#include <sqlpp11/core/enable_as.h>
-#include <sqlpp11/core/enable_join.h>
+#include <sqlpp11/core/operator/enable_as.h>
+#include <sqlpp11/core/basic/enable_join.h>
 
 namespace sqlpp
 {
diff --git a/include/sqlpp11/core/simple_column.h b/include/sqlpp11/core/clause/simple_column.h
similarity index 100%
rename from include/sqlpp11/core/simple_column.h
rename to include/sqlpp11/core/clause/simple_column.h
diff --git a/include/sqlpp11/core/single_table.h b/include/sqlpp11/core/clause/single_table.h
similarity index 100%
rename from include/sqlpp11/core/single_table.h
rename to include/sqlpp11/core/clause/single_table.h
diff --git a/include/sqlpp11/core/clause/update.h b/include/sqlpp11/core/clause/update.h
index 67f06a7b..7a9bc9e1 100644
--- a/include/sqlpp11/core/clause/update.h
+++ b/include/sqlpp11/core/clause/update.h
@@ -31,7 +31,7 @@
 #include <sqlpp11/core/type_traits.h>
 #include <sqlpp11/core/parameter_list.h>
 #include <sqlpp11/core/database/prepared_update.h>
-#include <sqlpp11/core/single_table.h>
+#include <sqlpp11/core/clause/single_table.h>
 #include <sqlpp11/core/clause/update_list.h>
 #include <sqlpp11/core/noop.h>
 #include <sqlpp11/core/clause/where.h>
diff --git a/include/sqlpp11/core/compat/make_unique.h b/include/sqlpp11/core/compat/make_unique.h
index 6d421fb2..923df574 100644
--- a/include/sqlpp11/core/compat/make_unique.h
+++ b/include/sqlpp11/core/compat/make_unique.h
@@ -34,15 +34,23 @@
 #define CXX_STD_VER __cplusplus
 #endif
 
+#if CXX_STD_VER >= 201402L
+
 namespace sqlpp
 {
-    template <typename T, typename... Args>
-    std::unique_ptr<T> make_unique(Args&&... args)
-    {
-#if CXX_STD_VER >= 201402L
-      return std::make_unique<T>(std::forward<Args>(args)...);
+  using ::std::make_unique;
+}
+
 #else
-      return std::unique_ptr<T>(new T(std::forward<Args>(args)...));
-#endif
-    }
+
+namespace sqlpp
+{
+  template <typename T, typename... Args>
+  std::unique_ptr<T> make_unique(Args&&... args)
+  {
+    return std::unique_ptr<T>(new T(std::forward<Args>(args)...));
+  }
 }  // namespace sqlpp
+
+#endif
+
diff --git a/include/sqlpp11/core/compat/type_traits.h b/include/sqlpp11/core/compat/type_traits.h
new file mode 100644
index 00000000..dd660290
--- /dev/null
+++ b/include/sqlpp11/core/compat/type_traits.h
@@ -0,0 +1,51 @@
+#pragma once
+
+/*
+ * Copyright (c) 2024, Roland Bock
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ *   Redistributions of source code must retain the above copyright notice, this
+ *   list of conditions and the following disclaimer.
+ *
+ *   Redistributions in binary form must reproduce the above copyright notice, this
+ *   list of conditions and the following disclaimer in the documentation and/or
+ *   other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
+ * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <type_traits>
+
+#ifdef _MSVC_LANG
+#define CXX_STD_VER _MSVC_LANG
+#else
+#define CXX_STD_VER __cplusplus
+#endif
+
+#if CXX_STD_VER >= 201703L
+namespace sqlpp
+{
+  using ::std::enable_if_t;
+}  // namespace sqlpp
+
+#else
+
+namespace sqlpp
+{
+  template <bool Condition, typename Type = void>
+  using enable_if_t = typename ::std::enable_if<Condition, Type>::type;
+}  // namespace sqlpp
+
+#endif
diff --git a/include/sqlpp11/core/function/lower.h b/include/sqlpp11/core/function/lower.h
index 7b48dda8..87838c41 100644
--- a/include/sqlpp11/core/function/lower.h
+++ b/include/sqlpp11/core/function/lower.h
@@ -61,7 +61,7 @@ namespace sqlpp
   }
 
   template<typename T>
-    using check_lower_args = std::enable_if_t<is_text<T>::value>;
+    using check_lower_args = ::sqlpp::enable_if_t<is_text<T>::value>;
 
   template <typename T, typename = check_lower_args<T>>
   auto lower(T t) -> lower_t<T>
diff --git a/include/sqlpp11/core/function/trim.h b/include/sqlpp11/core/function/trim.h
index 9779466a..6bbc5342 100644
--- a/include/sqlpp11/core/function/trim.h
+++ b/include/sqlpp11/core/function/trim.h
@@ -69,7 +69,7 @@ namespace sqlpp
   }
 
   template<typename T>
-    using check_trim_args = std::enable_if_t<is_text<T>::value>;
+    using check_trim_args = ::sqlpp::enable_if_t<is_text<T>::value>;
 
   template <typename T, typename = check_trim_args<T>>
   auto trim(T t) -> trim_t<T>
diff --git a/include/sqlpp11/core/function/upper.h b/include/sqlpp11/core/function/upper.h
index f55bb456..e3b5a730 100644
--- a/include/sqlpp11/core/function/upper.h
+++ b/include/sqlpp11/core/function/upper.h
@@ -61,7 +61,7 @@ namespace sqlpp
   }
 
   template<typename T>
-    using check_upper_args = std::enable_if_t<is_text<T>::value>;
+    using check_upper_args = ::sqlpp::enable_if_t<is_text<T>::value>;
 
   template <typename T, typename = check_upper_args<T>>
   auto upper(T t) -> upper_t<T>
diff --git a/include/sqlpp11/core/operator/any.h b/include/sqlpp11/core/operator/any.h
index 481d1024..467310b7 100644
--- a/include/sqlpp11/core/operator/any.h
+++ b/include/sqlpp11/core/operator/any.h
@@ -80,7 +80,7 @@ namespace sqlpp
   }
 
   template <typename Select>
-  using check_any_args = std::enable_if_t<has_value_type<Select>::value>;
+  using check_any_args = ::sqlpp::enable_if_t<has_value_type<Select>::value>;
 
   template <typename ...Policies, typename = check_any_args<statement_t<Policies...>>>
   auto any(statement_t<Policies...> t) -> any_t<statement_t<Policies...>>
diff --git a/include/sqlpp11/core/operator/arithmetic_expression.h b/include/sqlpp11/core/operator/arithmetic_expression.h
index 3ac80fbd..960560fc 100644
--- a/include/sqlpp11/core/operator/arithmetic_expression.h
+++ b/include/sqlpp11/core/operator/arithmetic_expression.h
@@ -29,8 +29,8 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include <utility>
 
 #include <sqlpp11/core/noop.h>
-#include <sqlpp11/core/enable_as.h>
-#include <sqlpp11/core/enable_comparison.h>
+#include <sqlpp11/core/operator/enable_as.h>
+#include <sqlpp11/core/operator/enable_comparison.h>
 #include <sqlpp11/core/type_traits.h>
 
 namespace sqlpp
@@ -56,7 +56,7 @@ namespace sqlpp
   };
 
   template <typename L, typename R>
-  using check_arithmetic_args = std::enable_if_t<is_numeric<L>::value and is_numeric<R>::value>;
+  using check_arithmetic_args = ::sqlpp::enable_if_t<is_numeric<L>::value and is_numeric<R>::value>;
 
 #warning: need to document that this is on purpose (not integral, or unsigned integral, or floating_point) because it is difficult to know for the library to know what the actual result type will be (it is difficult to guess in C++ already, and it is probably different from DB vendor to vendor).
   template <typename L, typename Operator, typename R>
@@ -142,7 +142,7 @@ namespace sqlpp
   }
 
   template <typename L, typename R>
-  using check_concatenation_args = std::enable_if_t<is_text<L>::value and is_text<R>::value>;
+  using check_concatenation_args = ::sqlpp::enable_if_t<is_text<L>::value and is_text<R>::value>;
 
   template <typename L, typename R, typename = check_concatenation_args<L, R>>
   constexpr auto operator+(L l, R r) -> arithmetic_expression<L, concatenation, R>
@@ -200,7 +200,7 @@ namespace sqlpp
   };
 
   template <typename L, typename R>
-  using check_modulus_args = std::enable_if_t<(is_integral<L>::value or is_unsigned_integral<L>::value) and (is_integral<R>::value or is_unsigned_integral<R>::value)>;
+  using check_modulus_args = ::sqlpp::enable_if_t<(is_integral<L>::value or is_unsigned_integral<L>::value) and (is_integral<R>::value or is_unsigned_integral<R>::value)>;
 
   template <typename L, typename R, typename = check_modulus_args<L, R>>
   constexpr auto operator%(L l, R r) -> arithmetic_expression<L, modulus, R>
diff --git a/include/sqlpp11/core/operator/as_expression.h b/include/sqlpp11/core/operator/as_expression.h
index 3210fa7e..3509e890 100644
--- a/include/sqlpp11/core/operator/as_expression.h
+++ b/include/sqlpp11/core/operator/as_expression.h
@@ -73,7 +73,7 @@ namespace sqlpp
     return context;
   }
   template <typename Expr, typename AliasProvider>
-  using check_as_args = std::enable_if_t<
+  using check_as_args = ::sqlpp::enable_if_t<
   has_value_type<Expr>::value and not is_alias_t<Expr>::value and has_name<AliasProvider>::value
   >;
 
diff --git a/include/sqlpp11/core/operator/assign_expression.h b/include/sqlpp11/core/operator/assign_expression.h
index 44c7f995..fe7bad43 100644
--- a/include/sqlpp11/core/operator/assign_expression.h
+++ b/include/sqlpp11/core/operator/assign_expression.h
@@ -51,10 +51,10 @@ namespace sqlpp
 
   template <typename L, typename R>
   using check_assign_args =
-      std::enable_if_t<values_are_comparable<L, R>::value and (can_be_null<L>::value or not can_be_null<R>::value)>;
+      ::sqlpp::enable_if_t<values_are_comparable<L, R>::value and (can_be_null<L>::value or not can_be_null<R>::value)>;
 
   template <typename L>
-  using check_assign_default_args = std::enable_if_t<has_default<L>::value>;
+  using check_assign_default_args = ::sqlpp::enable_if_t<has_default<L>::value>;
 
   template <typename L, typename Operator, typename R>
   struct is_assignment<assign_expression<L, Operator, R>> : public std::true_type {};
diff --git a/include/sqlpp11/core/operator/between_expression.h b/include/sqlpp11/core/operator/between_expression.h
index 06ce0883..df47b938 100644
--- a/include/sqlpp11/core/operator/between_expression.h
+++ b/include/sqlpp11/core/operator/between_expression.h
@@ -26,7 +26,7 @@ ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 
-#include <sqlpp11/core/enable_as.h>
+#include <sqlpp11/core/operator/enable_as.h>
 #include <sqlpp11/core/type_traits.h>
 #include <sqlpp11/core/logic.h>
 
@@ -49,7 +49,7 @@ namespace sqlpp
 
   template <typename L, typename R1, typename R2>
   using check_between_args =
-      std::enable_if_t<values_are_comparable<L, R1>::value and values_are_comparable<L, R2>::value>;
+      ::sqlpp::enable_if_t<values_are_comparable<L, R1>::value and values_are_comparable<L, R2>::value>;
 
   template <typename L, typename R1, typename R2>
   struct value_type_of<between_expression<L, R1, R2>>
@@ -78,7 +78,7 @@ namespace sqlpp
 
   template <typename L, typename... Args>
   constexpr auto in(L l, Args... args)
-      -> std::enable_if_t<((sizeof...(Args) > 0) and ... and values_are_compatible_v<L, Args>), between_t<L, Args...>>
+      -> ::sqlpp::enable_if_t<((sizeof...(Args) > 0) and ... and values_are_compatible_v<L, Args>), between_t<L, Args...>>
   {
     return between_t<L, Args...>{l, std::tuple{args...}};
   }
diff --git a/include/sqlpp11/core/operator/bit_expression.h b/include/sqlpp11/core/operator/bit_expression.h
index 396d0553..7b312958 100644
--- a/include/sqlpp11/core/operator/bit_expression.h
+++ b/include/sqlpp11/core/operator/bit_expression.h
@@ -28,7 +28,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #include <type_traits>
 
-#include <sqlpp11/core/enable_as.h>
+#include <sqlpp11/core/operator/enable_as.h>
 #include <sqlpp11/core/noop.h>
 #include <sqlpp11/core/type_traits.h>
 
@@ -65,7 +65,7 @@ namespace sqlpp
   };
 
   template <typename L, typename R>
-  using check_bit_expression_args = std::enable_if_t<is_integral<L>::value and (is_integral<R>::value or is_unsigned_integral<R>::value)>;
+  using check_bit_expression_args = ::sqlpp::enable_if_t<is_integral<L>::value and (is_integral<R>::value or is_unsigned_integral<R>::value)>;
 
 #if 0
   template <typename L, typename Operator, typename R>
diff --git a/include/sqlpp11/core/operator/comparison_expression.h b/include/sqlpp11/core/operator/comparison_expression.h
index 3eb6ec3d..72e56250 100644
--- a/include/sqlpp11/core/operator/comparison_expression.h
+++ b/include/sqlpp11/core/operator/comparison_expression.h
@@ -28,7 +28,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #include <utility>
 
-#include <sqlpp11/core/enable_as.h>
+#include <sqlpp11/core/operator/enable_as.h>
 #include <sqlpp11/core/operator/any.h>
 #include <sqlpp11/core/noop.h>
 #include <sqlpp11/core/type_traits.h>
@@ -50,7 +50,7 @@ namespace sqlpp
   };
 
   template <typename L, typename R>
-  using check_comparison_args = std::enable_if_t<values_are_comparable<L, R>::value>;
+  using check_comparison_args = ::sqlpp::enable_if_t<values_are_comparable<L, R>::value>;
 
   template <typename L, typename Operator, typename R>
   struct value_type_of<comparison_expression<L, Operator, R>>
@@ -258,7 +258,7 @@ namespace sqlpp
   };
 
   template <typename L, typename R>
-  using check_like_args = std::enable_if_t<is_text<L>::value and is_text<R>::value>;
+  using check_like_args = ::sqlpp::enable_if_t<is_text<L>::value and is_text<R>::value>;
 
   template <typename L, typename R, typename = check_comparison_args<L, R>>
   constexpr auto like(L l, R r) -> comparison_expression<L, op_like, R>
diff --git a/include/sqlpp11/core/enable_as.h b/include/sqlpp11/core/operator/enable_as.h
similarity index 100%
rename from include/sqlpp11/core/enable_as.h
rename to include/sqlpp11/core/operator/enable_as.h
diff --git a/include/sqlpp11/core/enable_comparison.h b/include/sqlpp11/core/operator/enable_comparison.h
similarity index 100%
rename from include/sqlpp11/core/enable_comparison.h
rename to include/sqlpp11/core/operator/enable_comparison.h
diff --git a/include/sqlpp11/core/operator/exists_expression.h b/include/sqlpp11/core/operator/exists_expression.h
index 8c99a6e5..001f4a71 100644
--- a/include/sqlpp11/core/operator/exists_expression.h
+++ b/include/sqlpp11/core/operator/exists_expression.h
@@ -29,7 +29,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include <type_traits>
 
 #include <sqlpp11/core/type_traits.h>
-#include <sqlpp11/core/enable_as.h>
+#include <sqlpp11/core/operator/enable_as.h>
 
 namespace sqlpp
 {
@@ -49,7 +49,7 @@ namespace sqlpp
   };
 
   template <typename Select>
-  using check_exists_arg = std::enable_if_t<is_statement_t<Select>::value and has_result_row_t<Select>::value>;
+  using check_exists_arg = ::sqlpp::enable_if_t<is_statement_t<Select>::value and has_result_row_t<Select>::value>;
 
   template <typename Select>
   struct value_type_of<exists_expression<Select>>
diff --git a/include/sqlpp11/core/operator/in_expression.h b/include/sqlpp11/core/operator/in_expression.h
index 47f295d9..968b2a78 100644
--- a/include/sqlpp11/core/operator/in_expression.h
+++ b/include/sqlpp11/core/operator/in_expression.h
@@ -29,7 +29,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include <tuple>
 #include <vector>
 
-#include <sqlpp11/core/enable_as.h>
+#include <sqlpp11/core/operator/enable_as.h>
 #include <sqlpp11/core/type_traits.h>
 #include <sqlpp11/core/logic.h>
 #include <sqlpp11/core/interpret_tuple.h>
@@ -70,7 +70,7 @@ namespace sqlpp
 
   template <typename L, typename... Args>
   using check_in_args =
-      std::enable_if_t<(sizeof...(Args) != 0) and logic::all_t<values_are_comparable<L, Args>::value...>::value>;
+      ::sqlpp::enable_if_t<(sizeof...(Args) != 0) and logic::all_t<values_are_comparable<L, Args>::value...>::value>;
 
   template <typename L, typename Operator, typename R>
   struct value_type_of<in_expression<L, Operator, std::vector<R>>>
diff --git a/include/sqlpp11/core/operator/logical_expression.h b/include/sqlpp11/core/operator/logical_expression.h
index d529a06c..1a6e3863 100644
--- a/include/sqlpp11/core/operator/logical_expression.h
+++ b/include/sqlpp11/core/operator/logical_expression.h
@@ -28,7 +28,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #include <type_traits>
 
-#include <sqlpp11/core/enable_as.h>
+#include <sqlpp11/core/operator/enable_as.h>
 #include <sqlpp11/core/query/dynamic.h>
 #include <sqlpp11/core/noop.h>
 //#include <sqlpp11/embrace.h>
@@ -55,7 +55,7 @@ namespace sqlpp
   };
 
   template <typename L, typename R>
-  using check_logical_args = std::enable_if_t<is_boolean<L>::value and is_boolean<R>::value>;
+  using check_logical_args = ::sqlpp::enable_if_t<is_boolean<L>::value and is_boolean<R>::value>;
 
   template <typename L, typename Operator, typename R>
   struct value_type_of<logical_expression<L, Operator, R>>
diff --git a/include/sqlpp11/core/operator/sort_order_expression.h b/include/sqlpp11/core/operator/sort_order_expression.h
index a1929a29..f73178e7 100644
--- a/include/sqlpp11/core/operator/sort_order_expression.h
+++ b/include/sqlpp11/core/operator/sort_order_expression.h
@@ -55,7 +55,7 @@ namespace sqlpp
   };
 
   template <typename L>
-  using check_sort_order_args = std::enable_if_t<values_are_comparable<L, L>::value>;
+  using check_sort_order_args = ::sqlpp::enable_if_t<values_are_comparable<L, L>::value>;
 
   template <typename L>
   struct nodes_of<sort_order_expression<L>>
diff --git a/include/sqlpp11/core/query/dynamic.h b/include/sqlpp11/core/query/dynamic.h
index 90977d6a..6a724e48 100644
--- a/include/sqlpp11/core/query/dynamic.h
+++ b/include/sqlpp11/core/query/dynamic.h
@@ -27,7 +27,7 @@
  */
 
 #include <sqlpp11/core/type_traits.h>
-#include <sqlpp11/core/enable_as.h>
+#include <sqlpp11/core/operator/enable_as.h>
 #include <sqlpp11/core/serialize.h>
 
 namespace sqlpp
@@ -88,7 +88,7 @@ namespace sqlpp
   }
 
   template <typename Expr>
-  using check_dynamic_args = std::enable_if_t<has_value_type<Expr>::value>;
+  using check_dynamic_args = ::sqlpp::enable_if_t<has_value_type<Expr>::value>;
 
   template <typename Expr, typename = check_dynamic_args<Expr>>
   auto dynamic(bool condition, Expr t) -> dynamic_t<Expr>
diff --git a/include/sqlpp11/core/type_traits.h b/include/sqlpp11/core/type_traits.h
index f9f84b68..dcd2920a 100644
--- a/include/sqlpp11/core/type_traits.h
+++ b/include/sqlpp11/core/type_traits.h
@@ -36,6 +36,7 @@
 #include <sqlpp11/core/name_tag.h>
 #include <sqlpp11/core/compat/optional.h>
 #include <sqlpp11/core/compat/string_view.h>
+#include <sqlpp11/core/compat/type_traits.h>
 #include <sqlpp11/core/compat/span.h>
 #include <sqlpp11/core/consistent.h>
 #include <sqlpp11/core/portable_static_assert.h>