Move schema creation class into `mysql/schema_creation.rb`

Current master branch includes many schema creation improvements in
MySQL. It extract these features to the appropriate file.

1 files changed, 57 insertions, 0 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/mysql/schema_creation.rb b/activerecord/lib/active_record/connection_adapters/mysql/schema_creation.rb
new file mode 100644
index 0000000000..1e2c859af9
--- /dev/null
+++ b/activerecord/lib/active_record/connection_adapters/mysql/schema_creation.rb
@@ -0,0 +1,57 @@
+module ActiveRecord
+  module ConnectionAdapters
+    module MySQL
+      class SchemaCreation < AbstractAdapter::SchemaCreation
+        private
+
+        def visit_DropForeignKey(name)
+          "DROP FOREIGN KEY #{name}"
+        end
+
+        def visit_ColumnDefinition(o)
+          o.sql_type = type_to_sql(o.type, o.limit, o.precision, o.scale, o.unsigned)
+          super
+        end
+
+        def visit_AddColumnDefinition(o)
+          add_column_position!(super, column_options(o.column))
+        end
+
+        def visit_ChangeColumnDefinition(o)
+          change_column_sql = "CHANGE #{quote_column_name(o.name)} #{accept(o.column)}"
+          add_column_position!(change_column_sql, column_options(o.column))
+        end
+
+        def column_options(o)
+          column_options = super
+          column_options[:charset] = o.charset
+          column_options
+        end
+
+        def add_column_options!(sql, options)
+          if options[:charset]
+            sql << " CHARACTER SET #{options[:charset]}"
+          end
+          if options[:collation]
+            sql << " COLLATE #{options[:collation]}"
+          end
+          super
+        end
+
+        def add_column_position!(sql, options)
+          if options[:first]
+            sql << " FIRST"
+          elsif options[:after]
+            sql << " AFTER #{quote_column_name(options[:after])}"
+          end
+          sql
+        end
+
+        def index_in_create(table_name, column_name, options)
+          index_name, index_type, index_columns, _, _, index_using = @conn.add_index_options(table_name, column_name, options)
+          "#{index_type} INDEX #{quote_column_name(index_name)} #{index_using} (#{index_columns}) "
+        end
+      end
+    end
+  end
+end