Add a method to RpcModule that transforms the module into a `RpcModul…

…e<()>`, i.e. removes the context. (#660)

* Add a method to RpcModule, `decontextualize`, that transforms the module into a `RpcModule<()>`, i.e. removes the context.

* Merging a module with an empty module cannot fail

* fmt

* Address grumbles

* Cleanup macro

* Update core/src/server/rpc_module.rs

Co-authored-by: Maciej Hirsz <1096222+maciejhirsz@users.noreply.github.com>

Co-authored-by: Maciej Hirsz <1096222+maciejhirsz@users.noreply.github.com>

core/src/server/rpc_module.rs

@@ -457,6 +457,13 @@ impl<Context> RpcModule<Context> {
 	pub fn new(ctx: Context) -> Self {
 		Self { ctx: Arc::new(ctx), methods: Default::default() }
 	}
+
+	/// Transform a module into an `RpcModule<()>` (unit context).
+	pub fn remove_context(self) -> RpcModule<()> {
+		let mut module = RpcModule::new(());
+		module.methods = self.methods;
+		module
+	}
 }
 
 impl<Context> From<RpcModule<Context>> for Methods {

examples/Cargo.toml

@@ -53,4 +53,4 @@ path = "core_client.rs"
 
 [[example]]
 name = "cors_server"
-path = "cors_server.rs"
+path = "cors_server.rs"

tests/tests/rpc_module.rs

@@ -31,6 +31,14 @@ use jsonrpsee::core::server::rpc_module::*;
 use jsonrpsee::types::{EmptyParams, Params};
 use serde::{Deserialize, Serialize};
 
+// Helper macro to assert that a binding is of a specific type.
+macro_rules! assert_type {
+	( $ty:ty, $expected:expr $(,)?) => {{
+		fn assert_type<Expected>(_expected: &Expected) {}
+		assert_type::<$ty>($expected)
+	}};
+}
+
 #[test]
 fn rpc_modules_with_different_contexts_can_be_merged() {
 	let cx = Vec::<u8>::new();
@@ -45,6 +53,14 @@ fn rpc_modules_with_different_contexts_can_be_merged() {
 	assert!(mod1.method("bla with String context").is_some());
 }
 
+#[test]
+fn flatten_rpc_modules() {
+	let mod1 = RpcModule::new(String::new());
+	assert_type!(RpcModule<String>, &mod1);
+	let unit_mod = mod1.remove_context();
+	assert_type!(RpcModule<()>, &unit_mod);
+}
+
 #[test]
 fn rpc_context_modules_can_register_subscriptions() {
 	let cx = ();