1 files changed, 105 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/type/value.rb b/activerecord/lib/active_record/type/value.rb
new file mode 100644
index 0000000000..60ae47db3d
--- /dev/null
+++ b/activerecord/lib/active_record/type/value.rb
@@ -0,0 +1,105 @@
+module ActiveRecord
+  module Type
+    class Value # :nodoc:
+      attr_reader :precision, :scale, :limit
+
+      # Valid options are +precision+, +scale+, and +limit+. They are only
+      # used when dumping schema.
+      def initialize(options = {})
+        options.assert_valid_keys(:precision, :scale, :limit)
+        @precision = options[:precision]
+        @scale = options[:scale]
+        @limit = options[:limit]
+      end
+
+      # The simplified type that this object represents. Returns a symbol such
+      # as +:string+ or +:integer+
+      def type; end
+
+      # Type casts a string from the database into the appropriate ruby type.
+      # Classes which do not need separate type casting behavior for database
+      # and user provided values should override +cast_value+ instead.
+      def type_cast_from_database(value)
+        type_cast(value)
+      end
+
+      # Type casts a value from user input (e.g. from a setter). This value may
+      # be a string from the form builder, or an already type cast value
+      # provided manually to a setter.
+      #
+      # Classes which do not need separate type casting behavior for database
+      # and user provided values should override +type_cast+ or +cast_value+
+      # instead.
+      def type_cast_from_user(value)
+        type_cast(value)
+      end
+
+      # Cast a value from the ruby type to a type that the database knows how
+      # to understand. The returned value from this method should be a
+      # +String+, +Numeric+, +Date+, +Time+, +Symbol+, +true+, +false+, or
+      # +nil+
+      def type_cast_for_database(value)
+        value
+      end
+
+      # Type cast a value for schema dumping. This method is private, as we are
+      # hoping to remove it entirely.
+      def type_cast_for_schema(value) # :nodoc:
+        value.inspect
+      end
+
+      # These predicates are not documented, as I need to look further into
+      # their use, and see if they can be removed entirely.
+      def text? # :nodoc:
+        false
+      end
+
+      def number? # :nodoc:
+        false
+      end
+
+      def binary? # :nodoc:
+        false
+      end
+
+      def klass # :nodoc:
+      end
+
+      # Determines whether a value has changed for dirty checking. +old_value+
+      # and +new_value+ will always be type-cast. Types should not need to
+      # override this method.
+      def changed?(old_value, new_value, _new_value_before_type_cast)
+        old_value != new_value
+      end
+
+      # Determines whether the mutable value has been modified since it was
+      # read. Returns +false+ by default. This method should not be overridden
+      # directly. Types which return a mutable value should include
+      # +Type::Mutable+, which will define this method.
+      def changed_in_place?(*)
+        false
+      end
+
+      def ==(other)
+        self.class == other.class &&
+          precision == other.precision &&
+          scale == other.scale &&
+          limit == other.limit
+      end
+
+      private
+
+      def type_cast(value)
+        cast_value(value) unless value.nil?
+      end
+
+      # Convenience method for types which do not need separate type casting
+      # behavior for user and database inputs. Called by
+      # +type_cast_from_database+ and +type_cast_from_user+ for all values
+      # except +nil+.
+      def cast_value(value) # :doc:
+        value
+      end
+    end
+  end
+end