allow annotate type with ffi too

examples/nim_timer/nim_timer.nim

@@ -8,32 +8,27 @@ declareLibrary("nimtimer")
 type NimTimer = object
   name: string # set at creation time, read back in each response
 
-ffiType:
-  type TimerConfig = object
-    name: string
+type TimerConfig {.ffi.} = object
+  name: string
 
-ffiType:
-  type EchoRequest = object
-    message: string
-    delayMs: int # how long chronos sleeps before replying
+type EchoRequest {.ffi.} = object
+  message: string
+  delayMs: int # how long chronos sleeps before replying
 
-ffiType:
-  type EchoResponse = object
-    echoed: string
-    timerName: string # proves that the timer's own state is accessible
+type EchoResponse {.ffi.} = object
+  echoed: string
+  timerName: string # proves that the timer's own state is accessible
 
-ffiType:
-  type ComplexRequest = object
-    messages: seq[EchoRequest]
-    tags: seq[string]
-    note: Option[string]
-    retries: Maybe[int]
+type ComplexRequest {.ffi.} = object
+  messages: seq[EchoRequest]
+  tags: seq[string]
+  note: Option[string]
+  retries: Maybe[int]
 
-ffiType:
-  type ComplexResponse = object
-    summary: string
-    itemCount: int
-    hasNote: bool
+type ComplexResponse {.ffi.} = object
+  summary: string
+  itemCount: int
+  hasNote: bool
 
 # --- Constructor -----------------------------------------------------------
 # Called once from Rust. Creates the FFIContext + NimTimer.

ffi/internal/ffi_macro.nim

@@ -10,6 +10,31 @@ when defined(ffiGenBindings):
 # String helpers used by multiple macros
 # ---------------------------------------------------------------------------
 
+proc registerFfiTypeInfo(typeDef: NimNode): NimNode {.compileTime.} =
+  ## Registers the type in ffiTypeRegistry for binding generation and returns
+  ## the clean typeDef. Serialization is handled by the generic overloads in serial.nim.
+  let typeName =
+    if typeDef[0].kind == nnkPostfix: typeDef[0][1] else: typeDef[0]
+  let typeNameStr = $typeName
+
+  var fieldMetas: seq[FFIFieldMeta] = @[]
+  let objTy = typeDef[2]
+  if objTy.kind == nnkObjectTy and objTy.len >= 3:
+    let recList = objTy[2]
+    if recList.kind == nnkRecList:
+      for identDef in recList:
+        if identDef.kind == nnkIdentDefs:
+          let fieldType = identDef[^2]
+          let fieldTypeName =
+            if fieldType.kind == nnkIdent: $fieldType
+            elif fieldType.kind == nnkPtrTy: "ptr " & $fieldType[0]
+            else: fieldType.repr
+          for i in 0 ..< identDef.len - 2:
+            fieldMetas.add(FFIFieldMeta(name: $identDef[i], typeName: fieldTypeName))
+
+  ffiTypeRegistry.add(FFITypeMeta(name: typeNameStr, fields: fieldMetas))
+  result = typeDef
+
 proc capitalizeFirstLetter(s: string): string =
   ## Returns `s` with the first character uppercased.
   if s.len == 0:
@@ -560,22 +585,29 @@ macro ffiRaw*(prc: untyped): untyped =
     echo result.repr
 
 macro ffi*(prc: untyped): untyped =
-  ## Simplified FFI macro — developer writes a clean Nim-idiomatic signature.
+  ## Simplified FFI macro — applies to procs or types.
   ##
-  ## The annotated proc must:
-  ##   - Have a first parameter of the library type (e.g. w: Waku)
-  ##   - Optionally have additional Nim-typed parameters
-  ##   - Return Future[Result[RetType, string]]
-  ##   - NOT include ctx, callback, or userData in its signature
+  ## On a type: `type Foo {.ffi.} = object` registers Foo for binding generation
+  ## and generates ffiSerialize/ffiDeserialize overloads.
   ##
-  ## Example:
+  ## On a proc: the annotated proc must have a first parameter of the library type,
+  ## optionally additional Nim-typed parameters, and return Future[Result[RetType, string]].
+  ## It must NOT include ctx, callback, or userData in its signature.
+  ##
+  ## Example (type):
+  ##   type EchoRequest {.ffi.} = object
+  ##     message: string
+  ##     delayMs: int
+  ##
+  ## Example (proc):
   ##   proc mylib_send*(w: MyLib, cfg: SendConfig): Future[Result[string, string]] {.ffi.} =
   ##     return ok("done")
-  ##
-  ## The macro generates:
-  ##   1. A named async helper proc (MyLibSendBody) containing the user body
-  ##   2. A registerReqFFI call that deserializes cstring args and calls the helper
-  ##   3. A C-exported proc with ctx/callback/userData + cstring params
+
+  if prc.kind == nnkTypeDef:
+    var cleanTypeDef = prc.copyNimTree()
+    if cleanTypeDef[0].kind == nnkPragmaExpr:
+      cleanTypeDef[0] = cleanTypeDef[0][0]
+    return registerFfiTypeInfo(cleanTypeDef)
 
   let procName = prc[0]
   let formalParams = prc[3]

ffi/serial.nim

@@ -1,4 +1,4 @@
-import std/[json, macros, sequtils, options]
+import std/[json, macros, options]
 import results
 import ./codegen/meta
 
@@ -81,6 +81,9 @@ proc ffiSerialize*[T](x: Option[T]): string =
   else:
     "null"
 
+proc ffiSerialize*[T: object](x: T): string =
+  $(%*x)
+
 proc ffiDeserialize*[T](s: cstring, _: typedesc[ptr T]): Result[ptr T, string] =
   try:
     let address = cast[ptr T](uint(parseJson($s).getBiggestInt()))
@@ -120,10 +123,16 @@ proc ffiDeserialize*[T](s: cstring, _: typedesc[Option[T]]): Result[Option[T], s
   except Exception as e:
     err(e.msg)
 
+proc ffiDeserialize*[T: object](s: cstring, _: typedesc[T]): Result[T, string] =
+  try:
+    ok(parseJson($s).to(T))
+  except Exception as e:
+    err(e.msg)
+
 macro ffiType*(body: untyped): untyped =
   ## Statement macro applied to a type declaration block.
-  ## Generates ffiSerialize and ffiDeserialize overloads for each type,
-  ## and registers the type in ffiTypeRegistry for binding generation.
+  ## Registers the type in ffiTypeRegistry for binding generation.
+  ## Serialization is handled by the generic ffiSerialize/ffiDeserialize overloads.
   ## Usage:
   ##   ffiType:
   ##     type Foo = object
@@ -136,56 +145,21 @@ macro ffiType*(body: untyped): untyped =
     else:
       typeDef[0]
 
-  # Collect field metadata for the codegen registry
   let typeNameStr = $typeName
   var fieldMetas: seq[FFIFieldMeta] = @[]
-  # typeDef layout: TypDef[name, genericParams, objectTy]
-  # objectTy layout: ObjectTy[empty, empty, recList]
   let objTy = typeDef[2]
   if objTy.kind == nnkObjectTy and objTy.len >= 3:
     let recList = objTy[2]
     if recList.kind == nnkRecList:
       for identDef in recList:
         if identDef.kind == nnkIdentDefs:
-          # identDef: [name1, ..., type, default]
           let fieldType = identDef[^2]
-          var fieldTypeName: string
-          if fieldType.kind == nnkIdent:
-            fieldTypeName = $fieldType
-          elif fieldType.kind == nnkPtrTy:
-            fieldTypeName = "ptr " & $fieldType[0]
-          else:
-            fieldTypeName = fieldType.repr
+          let fieldTypeName =
+            if fieldType.kind == nnkIdent: $fieldType
+            elif fieldType.kind == nnkPtrTy: "ptr " & $fieldType[0]
+            else: fieldType.repr
           for i in 0 ..< identDef.len - 2:
-            let fname = $identDef[i]
-            fieldMetas.add(FFIFieldMeta(name: fname, typeName: fieldTypeName))
+            fieldMetas.add(FFIFieldMeta(name: $identDef[i], typeName: fieldTypeName))
 
   ffiTypeRegistry.add(FFITypeMeta(name: typeNameStr, fields: fieldMetas))
-
-  let serializeProc = quote:
-    proc ffiSerialize*(x: `typeName`): string =
-      $(%*x)
-
-  var assignmentText = ""
-  for field in fieldMetas:
-    if assignmentText.len > 0:
-      assignmentText &= "\n"
-    assignmentText &=
-      "  result[\"" & field.name & "\"] = parseJson(ffiSerialize(x." & field.name & "))"
-  let jsonProc = parseStmt(
-    "proc `%`*(x: " & typeNameStr & "): JsonNode =\n  var result = newJObject()\n" &
-      assignmentText & "\n  return result\n"
-  )
-
-  let importJson = quote:
-    import json
-  let deserializeProc = quote:
-    proc ffiDeserialize*(
-        s: cstring, _: typedesc[`typeName`]
-    ): Result[`typeName`, string] =
-      try:
-        ok(parseJson($s).to(`typeName`))
-      except Exception as e:
-        err(e.msg)
-
-  result = newStmtList(importJson, body, serializeProc, jsonProc, deserializeProc)
+  result = body