Some minimal changes to be able to base the `nimlangserver` in `json_rpc` (#222)

* adds processClientHook

This is useful to shape the request and response to defined protocols (i.e. lsp)

* overloads tryRoute

* apply suggestions

* update test

json_rpc/router.nim

@@ -196,17 +196,15 @@ proc route*(router: RpcRouter, data: string):
 
   return reply
 
-proc tryRoute*(router: RpcRouter, data: JsonString,
+proc tryRoute*(router: RpcRouter, req: RequestRx,
                fut: var Future[JsonString]): Result[void, string] =
   ## Route to RPC, returns false if the method or params cannot be found.
-  ## Expects json input and returns json output.
+  ## Expects RequestRx input and returns json output.
   when defined(nimHasWarnBareExcept):
     {.push warning[BareExcept]:off.}
     {.push warning[UnreachableCode]:off.}
 
   try:
-    let req = JrpcSys.decode(data.string, RequestRx)
-
     if req.jsonrpc.isNone:
       return err("`jsonrpc` missing or invalid")
 
@@ -229,6 +227,16 @@ proc tryRoute*(router: RpcRouter, data: JsonString,
     {.pop warning[BareExcept]:on.}
     {.pop warning[UnreachableCode]:on.}
 
+proc tryRoute*(router: RpcRouter, data: JsonString,
+               fut: var Future[JsonString]): Result[void, string] =
+  ## Route to RPC, returns false if the method or params cannot be found.
+  ## Expects json input and returns json output.
+  try:
+    let req = JrpcSys.decode(data.string, RequestRx)
+    return router.tryRoute(req, fut)
+  except CatchableError as ex:
+    return err(ex.msg)
+
 macro rpc*(server: RpcRouter, path: static[string], body: untyped): untyped =
   ## Define a remote procedure call.
   ## Input and return parameters are defined using the ``do`` notation.

json_rpc/servers/socketserver.nim

@@ -18,6 +18,7 @@ export errors, server
 type
   RpcSocketServer* = ref object of RpcServer
     servers: seq[StreamServer]
+    processClientHook: StreamCallback2
 
 proc processClient(server: StreamServer, transport: StreamTransport) {.async: (raises: []), gcsafe.} =
   ## Process transport data to the RPC server
@@ -44,7 +45,7 @@ proc processClient(server: StreamServer, transport: StreamTransport) {.async: (r
 proc addStreamServer*(server: RpcSocketServer, address: TransportAddress) =
   try:
     info "Starting JSON-RPC socket server", address = $address
-    var transportServer = createStreamServer(address, processClient, {ReuseAddr}, udata = server)
+    var transportServer = createStreamServer(address, server.processClientHook, {ReuseAddr}, udata = server)
     server.servers.add(transportServer)
   except CatchableError as exc:
     error "Failed to create server", address = $address, message = exc.msg
@@ -135,7 +136,7 @@ proc addStreamServer*(server: RpcSocketServer, address: string, port: Port) =
                       "Could not setup server on " & address & ":" & $int(port))
 
 proc new(T: type RpcSocketServer): T =
-  T(router: RpcRouter.init(), servers: @[])
+  T(router: RpcRouter.init(), servers: @[], processClientHook: processClient)
 
 proc newRpcSocketServer*(): RpcSocketServer =
   RpcSocketServer.new()
@@ -155,6 +156,11 @@ proc newRpcSocketServer*(address: string, port: Port = Port(8545)): RpcSocketSer
   result = RpcSocketServer.new()
   result.addStreamServer(address, port)
 
+proc newRpcSocketServer*(processClientHook: StreamCallback2): RpcSocketServer =
+  ## Create new server with custom processClientHook.
+  result = RpcSocketServer.new()
+  result.processClientHook = processClientHook
+
 proc start*(server: RpcSocketServer) =
   ## Start the RPC server.
   for item in server.servers:

tests/testserverclient.nim

@@ -114,3 +114,20 @@ suite "Websocket Server/Client RPC with Compression":
   srv.stop()
   waitFor srv.closeWait()
 
+suite "Custom processClient":
+  test "Should be able to use custom processClient":
+    var wasCalled: bool = false
+    
+    proc processClientHook(server: StreamServer, transport: StreamTransport) {.async: (raises: []), gcsafe.} =
+      wasCalled = true
+    
+    var srv = newRpcSocketServer(processClientHook)
+    srv.addStreamServer("localhost", Port(8888))
+    var client = newRpcSocketClient()
+    srv.setupServer()
+    srv.start()
+    waitFor client.connect(srv.localAddress()[0])
+    asyncCheck client.call("", %[])
+    srv.stop()
+    waitFor srv.closeWait()
+    check wasCalled