allow CMake/compile option to DISABLE_GREASE (#377)

* allow CMake/compile option to DISABLE_GREASE

* make the DISABLE_GREASE default explicit

* clang format cleanup

CMakeLists.txt

@@ -9,6 +9,7 @@ option(TESTING    "Build tests" OFF)
 option(CLANG_TIDY "Perform linting with clang-tidy" OFF)
 option(SANITIZERS "Enable sanitizers" OFF)
 option(MLS_NAMESPACE_SUFFIX "Namespace Suffix for CXX and CMake Export")
+option(DISABLE_GREASE "Disables the inclusion of MLS protocol recommended GREASE values" OFF)
 
 if(MLS_NAMESPACE_SUFFIX)
     set(MLS_CXX_NAMESPACE "mls_${MLS_NAMESPACE_SUFFIX}" CACHE STRING "Top-level Namespace for CXX")
@@ -79,6 +80,10 @@ if("$ENV{MACOSX_DEPLOYMENT_TARGET}" STREQUAL "10.11")
   add_compile_options(-DVARIANT_COMPAT)
 endif()
 
+if (DISABLE_GREASE)
+  add_compile_options(-DDISABLE_GREASE)
+endif ()
+
 ###
 ### Enable testing
 ###

src/grease.cpp

@@ -6,6 +6,23 @@
 
 namespace MLS_NAMESPACE {
 
+#ifdef DISABLE_GREASE
+
+Capabilities
+grease(Capabilities&& capabilities,
+       [[maybe_unused]] const ExtensionList& extensions)
+{
+  return capabilities;
+}
+
+ExtensionList
+grease(ExtensionList&& extensions)
+{
+  return extensions;
+}
+
+#else
+
 // Randomness parmeters:
 // * Given a list of N items, insert max(1, rand(p_grease * N)) GREASE values
 // * Each GREASE value added is distinct, unless more than 15 values are needed
@@ -118,4 +135,6 @@ grease(ExtensionList&& extensions)
   return { ext };
 }
 
+#endif // DISABLE_GREASE
+
 } // namespace MLS_NAMESPACE