Send IR to Rust to generate rust source code using quote!
To pass IR across the FFI boundary we serialize it to a json string, pass the string to Rust, and return a string with generated Rust source code back.
Alternatives considered:
Protobuf instead of json
------------------------
using protobuf as a serialization format would have some advantages (defining types only once, we wouldn't have to write our own serialization logic in C++), we decided not to use it because:
* there is no approved way of using protobufs in Rust in google3 today, and we didn't want to special case us. We could still use protobuf on the C++ side and generate json using it, so at least we don't have to write serialization code ourselves.
* we felt going with json and manual serialization will be more flexible in the uncertain future
* we tossed a coin and json won
Implementing our own Rust code generator in C++
-----------------------------------------------
We sketched the code in unknown commit, and we decided going with Rust solution is more readable and maintainable. We also plan to use Clang syntax trees to generate C++ source code, of which quote!, proc_macro2, and syn are moral equivalents.
PiperOrigin-RevId: 389566607
diff --git a/rs_bindings_from_cc/ir.h b/rs_bindings_from_cc/ir.h
index 43bf33b..8c5cb68 100644
--- a/rs_bindings_from_cc/ir.h
+++ b/rs_bindings_from_cc/ir.h
@@ -16,6 +16,7 @@
#include "base/logging.h"
#include "third_party/absl/strings/cord.h"
+#include "third_party/json/src/json.hpp"
namespace rs_bindings_from_cc {
@@ -35,6 +36,8 @@
const absl::Cord &RsName() const { return rs_name_; }
+ nlohmann::json ToJson() const;
+
private:
absl::Cord rs_name_;
};
@@ -56,6 +59,8 @@
const absl::Cord &Ident() const { return identifier_; }
+ nlohmann::json ToJson() const;
+
private:
absl::Cord identifier_;
};
@@ -73,31 +78,18 @@
const Type &ParamType() const { return type_; }
const Identifier &Ident() const { return identifier_; }
+ nlohmann::json ToJson() const;
+
private:
Type type_;
Identifier identifier_;
};
-// All parameters of a function.
-//
-// Invariants:
-// `params` can be empty.
-class FuncParams {
- public:
- explicit FuncParams(std::vector<FuncParam> params)
- : params_(std::move(params)) {}
-
- const std::vector<FuncParam> &Params() const { return params_; }
-
- private:
- std::vector<FuncParam> params_;
-};
-
// A function involved in the bindings.
class Func {
public:
explicit Func(Identifier identifier, absl::Cord mangled_name,
- Type return_type, FuncParams params)
+ Type return_type, std::vector<FuncParam> params)
: identifier_(std::move(identifier)),
mangled_name_(std::move(mangled_name)),
return_type_(std::move(return_type)),
@@ -107,13 +99,15 @@
const Type &ReturnType() const { return return_type_; }
const Identifier &Ident() const { return identifier_; }
- const FuncParams &Params() const { return params_; }
+ const std::vector<FuncParam> &Params() const { return params_; }
+
+ nlohmann::json ToJson() const;
private:
Identifier identifier_;
absl::Cord mangled_name_;
Type return_type_;
- FuncParams params_;
+ std::vector<FuncParam> params_;
};
// A complete intermediate representation of bindings for publicly accessible
@@ -122,6 +116,8 @@
public:
explicit IR(std::vector<Func> functions) : functions_(std::move(functions)) {}
+ nlohmann::json ToJson() const;
+
private:
std::vector<Func> functions_;
};
