Collapse PG default extractoin of most types to single regex

For any type that is represented as a string and then type cast, we do
not need separate regular expressions for the various types. No function
will match this regex. User defined types *should* match this, so that
the type object can decide what to do with the value.

activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb

@@ -511,58 +511,16 @@ module ActiveRecord
           # makes this method very very slow.
           return default unless default
 
-          # TODO: The default extraction is related to the cast-type.
-          # we should probably make a type_map lookup and cast the default-
-          # expression accordingly
-          if oid.type == :enum && default =~ /\A'(.*)'::/
-            return $1
-          end
-
           case default
-            when /\A'(.*)'::(num|date|tstz|ts|int4|int8)range\z/m
-              $1
+            # Quoted types
+            when /\A[\(B]?'(.*)'::/m
+              $1.gsub(/''/, "'")
+            # Boolean types
+            when 'true', 'false'
+              default
             # Numeric types
             when /\A\(?(-?\d+(\.\d*)?\)?(::bigint)?)\z/
               $1
-            # Character types
-            when /\A\(?'(.*)'::.*\b(?:character varying|bpchar|text)\z/m
-              $1.gsub(/''/, "'")
-            # Binary data types
-            when /\A'(.*)'::bytea\z/m
-              $1
-            # Date/time types
-            when /\A'(.+)'::(?:time(?:stamp)? with(?:out)? time zone|date)\z/
-              $1
-            when /\A'(.*)'::interval\z/
-              $1
-            # Boolean type
-            when 'true'
-              true
-            when 'false'
-              false
-            # Geometric types
-            when /\A'(.*)'::(?:point|line|lseg|box|"?path"?|polygon|circle)\z/
-              $1
-            # Network address types
-            when /\A'(.*)'::(?:cidr|inet|macaddr)\z/
-              $1
-            # Bit string types
-            when /\AB'(.*)'::"?bit(?: varying)?"?\z/
-              $1
-            # XML type
-            when /\A'(.*)'::xml\z/m
-              $1
-            # Arrays
-            when /\A'(.*)'::"?\D+"?\[\]\z/
-              $1
-            # Hstore
-            when /\A'(.*)'::hstore\z/
-              $1
-            # JSON
-            when /\A'(.*)'::json\z/
-              $1
-            when /\A'(.*)'::money\z/
-              $1
             # Object identifier types
             when /\A-?\d+\z/
               $1

activerecord/test/cases/defaults_test.rb

@@ -206,6 +206,11 @@ if current_adapter?(:PostgreSQLAdapter)
       assert_equal "some text", Default.new.text_col, "Default of text column was not correctly parse after updating default using '::text' since postgreSQL will add parens to the default in db"
     end
 
+    def test_default_containing_quote_and_colons
+      @connection.execute "ALTER TABLE defaults ALTER COLUMN string_col SET DEFAULT 'foo''::bar'"
+      assert_equal "foo'::bar", Default.new.string_col
+    end
+
     teardown do
       @connection.schema_search_path = @old_search_path
       Default.reset_column_information