1 files changed, 40 insertions, 0 deletions
diff --git a/app/lib/scope_transformer.rb b/app/lib/scope_transformer.rb
new file mode 100644
index 000000000..fdfc6cf13
--- /dev/null
+++ b/app/lib/scope_transformer.rb
@@ -0,0 +1,40 @@
+# frozen_string_literal: true
+
+class ScopeTransformer < Parslet::Transform
+  class Scope
+    DEFAULT_TERM   = 'all'
+    DEFAULT_ACCESS = %w(read write).freeze
+
+    attr_reader :namespace, :term
+
+    def initialize(scope)
+      @namespace = scope[:namespace]&.to_s
+      @access    = scope[:access] ? [scope[:access].to_s] : DEFAULT_ACCESS.dup
+      @term      = scope[:term]&.to_s || DEFAULT_TERM
+    end
+
+    def key
+      @key ||= [@namespace, @term].compact.join('/')
+    end
+
+    def access
+      @access.join('/')
+    end
+
+    def merge(other_scope)
+      clone.merge!(other_scope)
+    end
+
+    def merge!(other_scope)
+      raise ArgumentError unless other_scope.namespace == namespace && other_scope.term == term
+
+      @access.concat(other_scope.instance_variable_get('@access'))
+      @access.uniq!
+      @access.sort!
+
+      self
+    end
+  end
+
+  rule(scope: subtree(:scope)) { Scope.new(scope) }
+end