1 files changed, 18 insertions, 1 deletions
diff --git a/lib/gitlab/ci/pipeline/expression/lexer.rb b/lib/gitlab/ci/pipeline/expression/lexer.rb
index e14edfae51d..22c210ae26b 100644
--- a/lib/gitlab/ci/pipeline/expression/lexer.rb
+++ b/lib/gitlab/ci/pipeline/expression/lexer.rb
@@ -20,6 +20,19 @@ module Gitlab
             Expression::Lexeme::NotMatches
           ].freeze
 
+          NEW_LEXEMES = [
+            Expression::Lexeme::Variable,
+            Expression::Lexeme::String,
+            Expression::Lexeme::Pattern,
+            Expression::Lexeme::Null,
+            Expression::Lexeme::Equals,
+            Expression::Lexeme::Matches,
+            Expression::Lexeme::NotEquals,
+            Expression::Lexeme::NotMatches,
+            Expression::Lexeme::And,
+            Expression::Lexeme::Or
+          ].freeze
+
           MAX_TOKENS = 100
 
           def initialize(statement, max_tokens: MAX_TOKENS)
@@ -45,7 +58,7 @@ module Gitlab
 
               return tokens if @scanner.eos?
 
-              lexeme = LEXEMES.find do |type|
+              lexeme = available_lexemes.find do |type|
                 type.scan(@scanner).tap do |token|
                   tokens.push(token) if token.present?
                 end
@@ -58,6 +71,10 @@ module Gitlab
 
             raise Lexer::SyntaxError, 'Too many tokens!'
           end
+
+          def available_lexemes
+            Feature.enabled?(:ci_variables_complex_expressions, default_enabled: true) ? NEW_LEXEMES : LEXEMES
+          end
         end
       end
     end