1 files changed, 130 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/type/adapter_specific_registry.rb b/activerecord/lib/active_record/type/adapter_specific_registry.rb
new file mode 100644
index 0000000000..d440eac619
--- /dev/null
+++ b/activerecord/lib/active_record/type/adapter_specific_registry.rb
@@ -0,0 +1,130 @@
+require 'active_model/type/registry'
+
+module ActiveRecord
+  # :stopdoc:
+  module Type
+    class AdapterSpecificRegistry < ActiveModel::Type::Registry
+      def add_modifier(options, klass, **args)
+        registrations << DecorationRegistration.new(options, klass, **args)
+      end
+
+      private
+
+      def registration_klass
+        Registration
+      end
+
+      def find_registration(symbol, *args)
+        registrations
+          .select { |registration| registration.matches?(symbol, *args) }
+          .max
+      end
+    end
+
+    class Registration
+      def initialize(name, block, adapter: nil, override: nil)
+        @name = name
+        @block = block
+        @adapter = adapter
+        @override = override
+      end
+
+      def call(_registry, *args, adapter: nil, **kwargs)
+        if kwargs.any? # https://bugs.ruby-lang.org/issues/10856
+          block.call(*args, **kwargs)
+        else
+          block.call(*args)
+        end
+      end
+
+      def matches?(type_name, *args, **kwargs)
+        type_name == name && matches_adapter?(**kwargs)
+      end
+
+      def <=>(other)
+        if conflicts_with?(other)
+          raise TypeConflictError.new("Type #{name} was registered for all
+                                      adapters, but shadows a native type with
+                                      the same name for #{other.adapter}".squish)
+        end
+        priority <=> other.priority
+      end
+
+      protected
+
+      attr_reader :name, :block, :adapter, :override
+
+      def priority
+        result = 0
+        if adapter
+          result |= 1
+        end
+        if override
+          result |= 2
+        end
+        result
+      end
+
+      def priority_except_adapter
+        priority & 0b111111100
+      end
+
+      private
+
+      def matches_adapter?(adapter: nil, **)
+        (self.adapter.nil? || adapter == self.adapter)
+      end
+
+      def conflicts_with?(other)
+        same_priority_except_adapter?(other) &&
+          has_adapter_conflict?(other)
+      end
+
+      def same_priority_except_adapter?(other)
+        priority_except_adapter == other.priority_except_adapter
+      end
+
+      def has_adapter_conflict?(other)
+        (override.nil? && other.adapter) ||
+          (adapter && other.override.nil?)
+      end
+    end
+
+    class DecorationRegistration < Registration
+      def initialize(options, klass, adapter: nil)
+        @options = options
+        @klass = klass
+        @adapter = adapter
+      end
+
+      def call(registry, *args, **kwargs)
+        subtype = registry.lookup(*args, **kwargs.except(*options.keys))
+        klass.new(subtype)
+      end
+
+      def matches?(*args, **kwargs)
+        matches_adapter?(**kwargs) && matches_options?(**kwargs)
+      end
+
+      def priority
+        super | 4
+      end
+
+      protected
+
+      attr_reader :options, :klass
+
+      private
+
+      def matches_options?(**kwargs)
+        options.all? do |key, value|
+          kwargs[key] == value
+        end
+      end
+    end
+  end
+
+  class TypeConflictError < StandardError
+  end
+  # :startdoc:
+end