Add support for build hooks

The following buildfiles are loaded (if present) at appropriate times from the
out_root subdirectories of a project:

build/bootstrap/pre-*.build   # before loading bootstrap.build
build/bootstrap/post-*.build  # after  loading bootstrap.build
build/root/pre-*.build        # before loading root.build
build/root/post-*.build       # after  loading root.build

1 files changed, 15 insertions, 0 deletions

diff --git a/build2/file.ixx b/build2/file.ixx
index 15fa8dc..ef944cf 100644
--- a/build2/file.ixx
+++ b/build2/file.ixx
@@ -26,4 +26,19 @@ namespace build2
     assert (phase == run_phase::match || phase == run_phase::execute);
     return import (pk, true);
   }
+
+  void
+  source_hooks (scope&, const dir_path&, bool);
+
+  inline void
+  bootstrap_pre (scope& root)
+  {
+    source_hooks (root, bootstrap_dir, true /* pre */);
+  }
+
+  inline void
+  bootstrap_post (scope& root)
+  {
+    source_hooks (root, bootstrap_dir, false /* pre */);
+  }
 }