1 files changed, 33 insertions, 0 deletions
diff --git a/lib/gitlab/ci/pipeline/expression/lexeme/pattern.rb b/lib/gitlab/ci/pipeline/expression/lexeme/pattern.rb
new file mode 100644
index 00000000000..9b239c29ea4
--- /dev/null
+++ b/lib/gitlab/ci/pipeline/expression/lexeme/pattern.rb
@@ -0,0 +1,33 @@
+module Gitlab
+  module Ci
+    module Pipeline
+      module Expression
+        module Lexeme
+          require_dependency 're2'
+
+          class Pattern < Lexeme::Value
+            PATTERN = %r{^/.+/[ismU]*$}.freeze
+
+            def initialize(regexp)
+              @value = regexp
+
+              unless Gitlab::UntrustedRegexp.valid?(@value)
+                raise Lexer::SyntaxError, 'Invalid regular expression!'
+              end
+            end
+
+            def evaluate(variables = {})
+              Gitlab::UntrustedRegexp.fabricate(@value)
+            rescue RegexpError
+              raise Expression::RuntimeError, 'Invalid regular expression!'
+            end
+
+            def self.build(string)
+              new(string)
+            end
+          end
+        end
+      end
+    end
+  end
+end