Moved aggregate functions to folder, added can_be_null attributes

count cannot be null, all others can if there are no lines to max or min
etc

include/sqlpp11/aggregate_functions.h

@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) 2013-2015, 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.
+ */
+
+#ifndef SQLPP_AGGREGATE_FUNCTIONS_H
+#define SQLPP_AGGREGATE_FUNCTIONS_H
+
+#include <sqlpp11/aggregate_functions/count.h>
+#include <sqlpp11/aggregate_functions/min.h>
+#include <sqlpp11/aggregate_functions/max.h>
+#include <sqlpp11/aggregate_functions/avg.h>
+#include <sqlpp11/aggregate_functions/sum.h>
+
+#endif

include/sqlpp11/aggregate_functions/avg.h

@@ -60,6 +60,7 @@ namespace sqlpp
   {
     using _traits = make_traits<floating_point, tag::is_expression, tag::is_selectable>;
     using _nodes = detail::type_vector<Expr, aggregate_function>;
+    using _can_be_null = std::true_type;
     using _is_aggregate_expression = std::true_type;
 
     static_assert(is_noop<Flag>::value or std::is_same<distinct_t, Flag>::value,

include/sqlpp11/aggregate_functions/count.h

@@ -62,8 +62,8 @@ namespace sqlpp
     using _traits = make_traits<integral, tag::is_expression /*, tag::is_selectable*/>;
 
     using _nodes = detail::type_vector<Expr, aggregate_function>;
-    using _is_aggregate_expression = std::true_type;
     using _can_be_null = std::false_type;
+    using _is_aggregate_expression = std::true_type;
 
     static_assert(is_noop<Flag>::value or std::is_same<distinct_t, Flag>::value,
                   "count() used with flag other than 'distinct'");

include/sqlpp11/aggregate_functions/max.h

@@ -59,6 +59,7 @@ namespace sqlpp
   {
     using _traits = make_traits<value_type_of<Expr>, tag::is_expression, tag::is_selectable>;
     using _nodes = detail::type_vector<Expr, aggregate_function>;
+    using _can_be_null = std::true_type;
     using _is_aggregate_expression = std::true_type;
 
     using _auto_alias_t = max_alias_t;

include/sqlpp11/aggregate_functions/min.h

@@ -59,6 +59,7 @@ namespace sqlpp
   {
     using _traits = make_traits<value_type_of<Expr>, tag::is_expression, tag::is_selectable>;
     using _nodes = detail::type_vector<Expr, aggregate_function>;
+    using _can_be_null = std::true_type;
     using _is_aggregate_expression = std::true_type;
 
     using _auto_alias_t = min_alias_t;

include/sqlpp11/aggregate_functions/sum.h

@@ -60,6 +60,7 @@ namespace sqlpp
   {
     using _traits = make_traits<value_type_of<Expr>, tag::is_expression, tag::is_selectable>;
     using _nodes = detail::type_vector<Expr, aggregate_function>;
+    using _can_be_null = std::true_type;
     using _is_aggregate_expression = std::true_type;
 
     static_assert(is_noop<Flag>::value or std::is_same<distinct_t, Flag>::value,

include/sqlpp11/functions.h

@@ -30,6 +30,7 @@
 #include <sqlpp11/parameter.h>
 #include <sqlpp11/parameter_list.h>
 #include <sqlpp11/data_types.h>
+#include <sqlpp11/aggregate_functions.h>
 #include <sqlpp11/in.h>
 #include <sqlpp11/not_in.h>
 #include <sqlpp11/is_null.h>
@@ -37,11 +38,6 @@
 #include <sqlpp11/exists.h>
 #include <sqlpp11/any.h>
 #include <sqlpp11/some.h>
-#include <sqlpp11/count.h>
-#include <sqlpp11/min.h>
-#include <sqlpp11/max.h>
-#include <sqlpp11/avg.h>
-#include <sqlpp11/sum.h>
 #include <sqlpp11/value_type.h>
 #include <sqlpp11/verbatim.h>  // Csaba Csoma suggests: unsafe_sql instead of verbatim
 #include <sqlpp11/verbatim_table.h>

include/sqlpp11/value_or_null.h

@@ -27,22 +27,8 @@
 #ifndef SQLPP_VALUE_OR_NULL_H
 #define SQLPP_VALUE_OR_NULL_H
 
-// FIXME: This is very similar to functions.h
-#include <sqlpp11/parameter.h>
-#include <sqlpp11/parameter_list.h>
-#include <sqlpp11/data_types.h>
-#include <sqlpp11/in.h>
-#include <sqlpp11/value_type.h>
-#include <sqlpp11/exists.h>
-#include <sqlpp11/any.h>
-#include <sqlpp11/some.h>
-#include <sqlpp11/count.h>
-#include <sqlpp11/min.h>
-#include <sqlpp11/max.h>
-#include <sqlpp11/avg.h>
-#include <sqlpp11/sum.h>
-#include <sqlpp11/verbatim_table.h>  // Csaba Csoma suggests: unsafe_sql instead of verbatim
-#include <sqlpp11/value_or_null.h>
+#include <sqlpp11/wrap_operand.h>
+#include <sqlpp11/type_traits.h>
 
 namespace sqlpp
 {