Add support for skipping already loaded/included buildfiles at top level

The idea is that a buildfile shall be included/loaded only once for any
given out_root.

1 files changed, 8 insertions, 0 deletions

diff --git a/build/scope b/build/scope
index b4f492d..e5c5fec 100644
--- a/build/scope
+++ b/build/scope
@@ -5,6 +5,8 @@
 #ifndef BUILD_SCOPE
 #define BUILD_SCOPE
 
+#include <unordered_set>
+
 #include <build/path>
 #include <build/path-map>
 #include <build/variable>
@@ -49,6 +51,12 @@ namespace build
     variable_map variables;
     prerequisite_set prerequisites;
 
+    // Set of buildfiles already loaded for this scope. The included
+    // buildfiles are checked against project root scope while
+    // imported -- against the overall root scope (root_scope).
+    //
+    std::unordered_set<path_type> buildfiles;
+
   private:
     iterator i_;
     scope* parent_;