3 files changed, 42 insertions, 0 deletions
diff --git a/paludis/dep_spec-fwd.hh b/paludis/dep_spec-fwd.hh
index fb968411b..f8f152b28 100644
--- a/paludis/dep_spec-fwd.hh
+++ b/paludis/dep_spec-fwd.hh
@@ -42,6 +42,7 @@ namespace paludis
     class FetchableURIDepSpec;
     class SimpleURIDepSpec;
     class AllDepSpec;
+    class ExactlyOneDepSpec;
     class AnyDepSpec;
     class ConditionalDepSpec;
     class BlockDepSpec;
diff --git a/paludis/dep_spec.cc b/paludis/dep_spec.cc
index 84a2fb731..602646997 100644
--- a/paludis/dep_spec.cc
+++ b/paludis/dep_spec.cc
@@ -125,6 +125,23 @@ AllDepSpec::clone() const
     return result;
 }
 
+ExactlyOneDepSpec::ExactlyOneDepSpec()
+{
+}
+
+void
+ExactlyOneDepSpec::need_keys_added() const
+{
+}
+
+std::shared_ptr<DepSpec>
+ExactlyOneDepSpec::clone() const
+{
+    std::shared_ptr<ExactlyOneDepSpec> result(std::make_shared<ExactlyOneDepSpec>());
+    result->set_annotations_key(annotations_key());
+    return result;
+}
+
 namespace paludis
 {
     template <>
diff --git a/paludis/dep_spec.hh b/paludis/dep_spec.hh
index 0b99291be..fc3584cf5 100644
--- a/paludis/dep_spec.hh
+++ b/paludis/dep_spec.hh
@@ -152,6 +152,30 @@ namespace paludis
     };
 
     /**
+     * Represents a ^^ ( first second third ) group of requirements.
+     *
+     * \ingroup g_dep_spec
+     * \nosubgrouping
+     * \since 0.56
+     */
+    class PALUDIS_VISIBLE ExactlyOneDepSpec :
+        public DepSpec
+    {
+        protected:
+            virtual void need_keys_added() const;
+
+        public:
+            ///\name Basic operations
+            ///\{
+
+            ExactlyOneDepSpec();
+
+            ///\}
+
+            virtual std::shared_ptr<DepSpec> clone() const PALUDIS_ATTRIBUTE((warn_unused_result));
+    };
+
+    /**
      * Represents a dependency spec whose children should only be considered
      * upon a certain condition (for example, a use dependency block).
      *