1 files changed, 69 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
index 7949bcb5ce..0ebe46be55 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
@@ -100,6 +100,75 @@ module ActiveRecord
         @visitor             = nil
       end
 
+      class SchemaCreation
+        def initialize(conn)
+          @conn  = conn
+          @cache = {}
+        end
+
+        def accept(o)
+          m = @cache[o.class] ||= "visit_#{o.class.name.split('::').last}"
+          send m, o
+        end
+
+        private
+
+        def visit_AlterTable(o)
+          sql = "ALTER TABLE #{quote_table_name(o.name)} "
+          sql << o.adds.map { |col| visit_AddColumn col }.join(' ')
+        end
+
+        def visit_AddColumn(o)
+          sql_type = type_to_sql(o.type.to_sym, o.limit, o.precision, o.scale)
+          sql = "ADD #{quote_column_name(o.name)} #{sql_type}"
+          add_column_options!(sql, column_options(o))
+        end
+
+        def visit_ColumnDefinition(o)
+          sql_type = type_to_sql(o.type.to_sym, o.limit, o.precision, o.scale)
+          column_sql = "#{quote_column_name(o.name)} #{sql_type}"
+          add_column_options!(column_sql, column_options(o)) unless o.primary_key?
+          column_sql
+        end
+
+        def visit_TableDefinition(o)
+          create_sql = "CREATE#{' TEMPORARY' if o.temporary} TABLE "
+          create_sql << "#{quote_table_name(o.name)} ("
+          create_sql << o.columns.map { |c| accept c }.join(', ')
+          create_sql << ") #{o.options}"
+          create_sql
+        end
+
+        def column_options(o)
+          column_options = {}
+          column_options[:null] = o.null unless o.null.nil?
+          column_options[:default] = o.default unless o.default.nil?
+          column_options[:column] = o
+          column_options
+        end
+
+        def quote_column_name(name)
+          @conn.quote_column_name name
+        end
+
+        def quote_table_name(name)
+          @conn.quote_table_name name
+        end
+
+        def type_to_sql(type, limit, precision, scale)
+          @conn.type_to_sql type.to_sym, limit, precision, scale
+        end
+
+        def add_column_options!(column_sql, column_options)
+          @conn.add_column_options! column_sql, column_options
+          column_sql
+        end
+      end
+
+      def schema_creation
+        SchemaCreation.new self
+      end
+
       def lease
         synchronize do
           unless in_use