(* simple-rpc.sig
 * 2004 Matthew Fluet (mfluet@acm.org)
 *  Ported to MLton threads.
 *)

(* simple-rpc.sml
 *
 * COPYRIGHT (c) 1997 AT&T Labs Research.
 *
 * Generators for simple RPC protocols.
 *)

structure SimpleRPC : SIMPLE_RPC =
   struct

      type 'a event = 'a CML.event

      fun call reqMB arg = 
         let val replV = SyncVar.iVar()
         in
            Mailbox.send(reqMB, (arg, replV))
            ; SyncVar.iGet replV
         end

      fun mkRPC f = 
         let
            val reqMB = Mailbox.mailbox()
            val entryEvt = 
               CML.wrap 
               (Mailbox.recvEvt reqMB, fn (arg, replV) => 
                SyncVar.iPut(replV, f arg))
         in
            {call = call reqMB, entryEvt = entryEvt}
         end

      fun mkRPC_In f = 
         let
            val reqMB = Mailbox.mailbox()
            val reqEvt = Mailbox.recvEvt reqMB
            fun entryEvt state = 
               CML.wrap 
               (reqEvt, fn (arg, replV) => 
                SyncVar.iPut(replV, f(arg, state)))
         in
            {call = call reqMB, entryEvt = entryEvt}
         end

      fun mkRPC_Out f = 
         let
            val reqMB = Mailbox.mailbox()
            val reqEvt = Mailbox.recvEvt reqMB
            val entryEvt = 
               CML.wrap 
               (reqEvt, fn (arg, replV) => 
                let val (res, state') = f arg
                in SyncVar.iPut(replV, res); state'
                end)
         in
            {call = call reqMB, entryEvt = entryEvt}
         end

      fun mkRPC_InOut f = 
         let
            val reqMB = Mailbox.mailbox()
            val reqEvt = Mailbox.recvEvt reqMB
            fun entryEvt state = 
               CML.wrap 
               (reqEvt, fn (arg, replV) => 
                let val (res, state') = f(arg, state)
                in SyncVar.iPut(replV, res); state'
                end)
         in
            {call = call reqMB, entryEvt = entryEvt}
         end
   end