NULL handling improvements

Add support for specifying NULL-ness for types with built-in mapping.
Handle Oracle [N]VARCHAR2 and SQLite FLOAT oddities using this mechanism
instead of overriding it at the schema generation level.

Also use the is_null argument that is passed to value_traits::init_image()
to indicate whether the value can be NULL.

2 files changed, 25 insertions, 65 deletions

diff --git a/odb/relational/oracle/context.cxx b/odb/relational/oracle/context.cxx
index 01b690a..4ba8659 100644
--- a/odb/relational/oracle/context.cxx
+++ b/odb/relational/oracle/context.cxx
@@ -20,38 +20,41 @@ namespace relational
     {
       struct type_map_entry
       {
-        const char* const cxx_type;
-        const char* const db_type;
-        const char* const db_id_type;
+        char const* const cxx_type;
+        char const* const db_type;
+        char const* const db_id_type;
+        bool const null;
       };
 
       type_map_entry type_map[] =
       {
-        {"bool", "NUMBER(1)", 0},
+        {"bool", "NUMBER(1)", 0, false},
 
-        {"char", "NUMBER(3)", 0},
-        {"signed char", "NUMBER(3)", 0},
-        {"unsigned char", "NUMBER(3)", 0},
+        {"char", "NUMBER(3)", 0, false},
+        {"signed char", "NUMBER(3)", 0, false},
+        {"unsigned char", "NUMBER(3)", 0, false},
 
-        {"short int", "NUMBER(5)", 0},
-        {"short unsigned int", "NUMBER(5)", 0},
+        {"short int", "NUMBER(5)", 0, false},
+        {"short unsigned int", "NUMBER(5)", 0, false},
 
-        {"int", "NUMBER(10)", 0},
-        {"unsigned int", "NUMBER(10)", 0},
+        {"int", "NUMBER(10)", 0, false},
+        {"unsigned int", "NUMBER(10)", 0, false},
 
-        {"long int", "NUMBER(19)", 0},
-        {"long unsigned int", "NUMBER(20)", 0},
+        {"long int", "NUMBER(19)", 0, false},
+        {"long unsigned int", "NUMBER(20)", 0, false},
 
-        {"long long int", "NUMBER(19)", 0},
-        {"long long unsigned int", "NUMBER(20)", 0},
+        {"long long int", "NUMBER(19)", 0, false},
+        {"long long unsigned int", "NUMBER(20)", 0, false},
 
-        {"float", "BINARY_FLOAT", 0},
-        {"double", "BINARY_DOUBLE", 0},
+        {"float", "BINARY_FLOAT", 0, false},
+        {"double", "BINARY_DOUBLE", 0, false},
 
-        {"::std::string", "VARCHAR2(512)", 0},
+        // Oracle treats empty VARCHAR2 (and NVARCHAR2) strings as NULL.
+        //
+        {"::std::string", "VARCHAR2(512)", 0, true},
 
-        {"::size_t", "NUMBER(20)", 0},
-        {"::std::size_t", "NUMBER(20)", 0}
+        {"::size_t", "NUMBER(20)", 0, false},
+        {"::std::size_t", "NUMBER(20)", 0, false}
       };
     }
 
@@ -92,7 +95,8 @@ namespace relational
 
         type_map_type::value_type v (
           e.cxx_type,
-          db_type_type (e.db_type, e.db_id_type ? e.db_id_type : e.db_type));
+          db_type_type (
+            e.db_type, e.db_id_type ? e.db_id_type : e.db_type, e.null));
 
         data_->type_map_.insert (v);
       }
diff --git a/odb/relational/oracle/schema.cxx b/odb/relational/oracle/schema.cxx
index 29c1130..f07e0d6 100644
--- a/odb/relational/oracle/schema.cxx
+++ b/odb/relational/oracle/schema.cxx
@@ -159,50 +159,6 @@ namespace relational
       };
       entry<create_table> create_table_;
 
-      struct create_column: relational::create_column, context
-      {
-        create_column (base const& x): base (x) {}
-
-        virtual void
-        null (sema_rel::column& c)
-        {
-          // Oracle interprets empty VARCHAR2 and NVARCHAR2 strings as
-          // NULL. As an empty string is valid within the C++ context,
-          // VARCHAR2 and NVARCHAR2 columns are always specified as
-          // nullable, except when are a part of a primary key.
-          //
-          if (!c.null ())
-          {
-            // This should never fail since we have already parsed this.
-            //
-            sql_type const& t (parse_sql_type (c.type ()));
-
-            if (t.type == sql_type::VARCHAR2 || t.type == sql_type::NVARCHAR2)
-            {
-              // See if this column is a part of a primary key.
-              //
-              bool pk (false);
-
-              for (sema_rel::column::contained_iterator i (
-                     c.contained_begin ()); i != c.contained_end (); ++i)
-              {
-                if (i->key ().is_a<sema_rel::primary_key> ())
-                {
-                  pk = true;
-                  break;
-                }
-              }
-
-              if (!pk)
-                return;
-            }
-          }
-
-          base::null (c);
-        }
-      };
-      entry<create_column> create_column_;
-
       struct create_foreign_key: relational::create_foreign_key, context
       {
         create_foreign_key (schema_format f, relational::create_table& ct)