src: add an ExternalReferenceRegistry class

Add an ExternalReferenceRegistry class for registering static
external references.

To register the external JS to C++ references created in a binding
(e.g. when a FunctionTemplate is created):

- Add the binding name (same as the id used for `internalBinding()`
  and `NODE_MODULE_CONTEXT_AWARE_INTERNAL`) to
  `EXTERNAL_REFERENCE_BINDING_LIST` in `src/node_external_reference.h`.
- In the file where the binding is implemented, create a registration
  function to register the static C++ references (e.g. the C++
  functions in `v8::FunctionCallback` associated with the function
  templates), like this:

  ```c++
  void RegisterExternalReferences(
          ExternalReferenceRegistry* registry) {
    registry->Register(cpp_func_1);
  }
  ```
- At the end of the file where `NODE_MODULE_CONTEXT_AWARE_INTERNAL` is
  also usually called, register the registration function with

  ```
  NODE_MODULE_EXTERNAL_REFERENCE(binding_name,
                                 RegisterExternalReferences);
  ```

PR-URL: https://github.com/nodejs/node/pull/32984
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Daniel Bevenius <daniel.bevenius@gmail.com>

1 files changed, 22 insertions, 0 deletions

diff --git a/src/node_external_reference.cc b/src/node_external_reference.cc
new file mode 100644
index 00000000000..73e1489865d
--- /dev/null
+++ b/src/node_external_reference.cc
@@ -0,0 +1,22 @@
+#include "node_external_reference.h"
+#include <cinttypes>
+#include <vector>
+#include "util.h"
+
+namespace node {
+
+const std::vector<intptr_t>& ExternalReferenceRegistry::external_references() {
+  CHECK(!is_finalized_);
+  external_references_.push_back(reinterpret_cast<intptr_t>(nullptr));
+  is_finalized_ = true;
+  return external_references_;
+}
+
+ExternalReferenceRegistry::ExternalReferenceRegistry() {
+#define V(modname) _register_external_reference_##modname(this);
+  EXTERNAL_REFERENCE_BINDING_LIST(V)
+#undef V
+  // TODO(joyeecheung): collect more external references here.
+}
+
+}  // namespace node