From eddfa409335f48df422aa644c0cae8f9a84e4721 Mon Sep 17 00:00:00 2001
From: "NGnius (Graham)" <ngniusness@gmail.com>
Date: Sun, 16 Apr 2023 14:41:04 -0400
Subject: [PATCH] Add higher-level code gen traits

---
 Cargo.lock                         |  2 +-
 nrpc-build/Cargo.toml              |  2 +-
 nrpc-build/src/lib.rs              |  2 ++
 nrpc-build/src/token_gen_traits.rs | 48 ++++++++++++++++++++++++++++++
 4 files changed, 52 insertions(+), 2 deletions(-)
 create mode 100644 nrpc-build/src/token_gen_traits.rs

diff --git a/Cargo.lock b/Cargo.lock
index 7421b97..049e796 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -290,7 +290,7 @@ dependencies = [
 
 [[package]]
 name = "nrpc-build"
-version = "0.3.0"
+version = "0.4.0"
 dependencies = [
  "nrpc",
  "prettyplease 0.2.4",
diff --git a/nrpc-build/Cargo.toml b/nrpc-build/Cargo.toml
index b0253c4..3b8859c 100644
--- a/nrpc-build/Cargo.toml
+++ b/nrpc-build/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "nrpc-build"
-version = "0.3.0"
+version = "0.4.0"
 edition = "2021"
 license = "Apache-2.0"
 repository = "https://github.com/NGnius/nRPC"
diff --git a/nrpc-build/src/lib.rs b/nrpc-build/src/lib.rs
index 206ab8f..0ac75dc 100644
--- a/nrpc-build/src/lib.rs
+++ b/nrpc-build/src/lib.rs
@@ -1,7 +1,9 @@
 mod builder;
 mod preprocessor;
 mod service_gen;
+mod token_gen_traits;
 
 pub use builder::{compile, compile_servers, compile_clients, Transpiler};
 pub use preprocessor::Preprocessor;
 pub(crate) use service_gen::ProtobufServiceGenerator;
+pub use token_gen_traits::{IServiceGenerator, IPreprocessor, AbstractImpl};
diff --git a/nrpc-build/src/token_gen_traits.rs b/nrpc-build/src/token_gen_traits.rs
new file mode 100644
index 0000000..5d18a78
--- /dev/null
+++ b/nrpc-build/src/token_gen_traits.rs
@@ -0,0 +1,48 @@
+use prost_build::Service;
+use prost_types::FileDescriptorSet;
+use proc_macro2::TokenStream;
+
+/// Higher-level abstraction of prost_build::ServiceGenerator
+pub trait IServiceGenerator {
+    fn generate(&mut self, service: Service) -> TokenStream;
+}
+
+/// Higher-level abstraction of crate::Preprocessor
+pub trait IPreprocessor {
+    fn process(&mut self, fds: &mut FileDescriptorSet) -> TokenStream;
+}
+
+/// Low-level interop for high-level traits IServiceGenerator and IPreprocessor
+pub struct AbstractImpl<X>(X);
+
+impl<X> AbstractImpl<X> {
+    pub fn inner(self) -> X {
+        self.0
+    }
+
+    pub fn outer(value: X) -> Self {
+        Self(value)
+    }
+}
+
+impl<X> std::convert::From<X> for AbstractImpl<X> {
+    fn from(value: X) -> Self {
+        Self(value)
+    }
+}
+
+impl<X: IServiceGenerator> prost_build::ServiceGenerator for AbstractImpl<X> {
+    fn generate(&mut self, service: Service, buf: &mut String) {
+        let gen_code: syn::File = syn::parse2(self.0.generate(service)).expect("invalid tokenstream");
+        let code_str = prettyplease::unparse(&gen_code);
+        buf.push_str(&code_str);
+    }
+}
+
+impl<X: IPreprocessor> super::Preprocessor for AbstractImpl<X> {
+    fn process(&mut self, fds: &mut FileDescriptorSet, buf: &mut String) {
+        let gen_code: syn::File = syn::parse2(self.0.process(fds)).expect("invalid tokenstream");
+        let code_str = prettyplease::unparse(&gen_code);
+        buf.push_str(&code_str);
+    }
+}