1 files changed, 37 insertions, 0 deletions
diff --git a/lib/gitlab/ci/build/rules.rb b/lib/gitlab/ci/build/rules.rb
new file mode 100644
index 00000000000..89623a809c9
--- /dev/null
+++ b/lib/gitlab/ci/build/rules.rb
@@ -0,0 +1,37 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Ci
+    module Build
+      class Rules
+        include ::Gitlab::Utils::StrongMemoize
+
+        Result = Struct.new(:when, :start_in)
+
+        def initialize(rule_hashes, default_when = 'on_success')
+          @rule_list    = Rule.fabricate_list(rule_hashes)
+          @default_when = default_when
+        end
+
+        def evaluate(pipeline, build)
+          if @rule_list.nil?
+            Result.new(@default_when)
+          elsif matched_rule = match_rule(pipeline, build)
+            Result.new(
+              matched_rule.attributes[:when] || @default_when,
+              matched_rule.attributes[:start_in]
+            )
+          else
+            Result.new('never')
+          end
+        end
+
+        private
+
+        def match_rule(pipeline, build)
+          @rule_list.find { |rule| rule.matches?(pipeline, build) }
+        end
+      end
+    end
+  end
+end