Support negative matches

This adds support for != and !~ operators
giving more flexibility in comparing values

4 files changed, 74 insertions, 2 deletions

diff --git a/lib/gitlab/ci/pipeline/expression/lexeme/not_equals.rb b/lib/gitlab/ci/pipeline/expression/lexeme/not_equals.rb
new file mode 100644
index 00000000000..5fcc9406cc8
--- /dev/null
+++ b/lib/gitlab/ci/pipeline/expression/lexeme/not_equals.rb
@@ -0,0 +1,28 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Ci
+    module Pipeline
+      module Expression
+        module Lexeme
+          class NotEquals < Lexeme::Operator
+            PATTERN = /!=/.freeze
+
+            def initialize(left, right)
+              @left = left
+              @right = right
+            end
+
+            def evaluate(variables = {})
+              @left.evaluate(variables) != @right.evaluate(variables)
+            end
+
+            def self.build(_value, behind, ahead)
+              new(behind, ahead)
+            end
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/ci/pipeline/expression/lexeme/not_matches.rb b/lib/gitlab/ci/pipeline/expression/lexeme/not_matches.rb
new file mode 100644
index 00000000000..14544d33e25
--- /dev/null
+++ b/lib/gitlab/ci/pipeline/expression/lexeme/not_matches.rb
@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Ci
+    module Pipeline
+      module Expression
+        module Lexeme
+          class NotMatches < Lexeme::Operator
+            PATTERN = /\!~/.freeze
+
+            def initialize(left, right)
+              @left = left
+              @right = right
+            end
+
+            def evaluate(variables = {})
+              text = @left.evaluate(variables)
+              regexp = @right.evaluate(variables)
+
+              regexp.scan(text.to_s).none?
+            end
+
+            def self.build(_value, behind, ahead)
+              new(behind, ahead)
+            end
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/ci/pipeline/expression/lexer.rb b/lib/gitlab/ci/pipeline/expression/lexer.rb
index f26542361a2..e14edfae51d 100644
--- a/lib/gitlab/ci/pipeline/expression/lexer.rb
+++ b/lib/gitlab/ci/pipeline/expression/lexer.rb
@@ -15,7 +15,9 @@ module Gitlab
             Expression::Lexeme::Pattern,
             Expression::Lexeme::Null,
             Expression::Lexeme::Equals,
-            Expression::Lexeme::Matches
+            Expression::Lexeme::Matches,
+            Expression::Lexeme::NotEquals,
+            Expression::Lexeme::NotMatches
           ].freeze
 
           MAX_TOKENS = 100
diff --git a/lib/gitlab/ci/pipeline/expression/statement.rb b/lib/gitlab/ci/pipeline/expression/statement.rb
index b03611f756e..ab5ae9caeea 100644
--- a/lib/gitlab/ci/pipeline/expression/statement.rb
+++ b/lib/gitlab/ci/pipeline/expression/statement.rb
@@ -8,13 +8,24 @@ module Gitlab
           StatementError = Class.new(Expression::ExpressionError)
 
           GRAMMAR = [
+            # presence matchers
             %w[variable],
+
+            # positive matchers
             %w[variable equals string],
             %w[variable equals variable],
             %w[variable equals null],
             %w[string equals variable],
             %w[null equals variable],
-            %w[variable matches pattern]
+            %w[variable matches pattern],
+
+            # negative matchers
+            %w[variable notequals string],
+            %w[variable notequals variable],
+            %w[variable notequals null],
+            %w[string notequals variable],
+            %w[null notequals variable],
+            %w[variable notmatches pattern]
           ].freeze
 
           def initialize(statement, variables = {})