1 files changed, 43 insertions, 0 deletions
diff --git a/lib/gitlab/ci/config/entry/simplifiable.rb b/lib/gitlab/ci/config/entry/simplifiable.rb
new file mode 100644
index 00000000000..12764629686
--- /dev/null
+++ b/lib/gitlab/ci/config/entry/simplifiable.rb
@@ -0,0 +1,43 @@
+module Gitlab
+  module Ci
+    class Config
+      module Entry
+        class Simplifiable < SimpleDelegator
+          EntryStrategy = Struct.new(:name, :condition)
+
+          def initialize(config, **metadata)
+            unless self.class.const_defined?(:UnknownStrategy)
+              raise ArgumentError, 'UndefinedStrategy not available!'
+            end
+
+            strategy = self.class.strategies.find do |variant|
+              variant.condition.call(config)
+            end
+
+            entry = self.class.entry_class(strategy)
+
+            super(entry.new(config, metadata))
+          end
+
+          def self.strategy(name, **opts)
+            EntryStrategy.new(name, opts.fetch(:if)).tap do |strategy|
+              strategies.append(strategy)
+            end
+          end
+
+          def self.strategies
+            @strategies ||= []
+          end
+
+          def self.entry_class(strategy)
+            if strategy.present?
+              self.const_get(strategy.name)
+            else
+              self::UnknownStrategy
+            end
+          end
+        end
+      end
+    end
+  end
+end