New upb_msg code and Lua bindings around it.

There are still some things that are unfinished,
but we are at parity with what Lua had before.

1 files changed, 41 insertions, 53 deletions

diff --git a/upb/bindings/lua/upb/pb.c b/upb/bindings/lua/upb/pb.c
index f095a61..d6f13d9 100644
--- a/upb/bindings/lua/upb/pb.c
+++ b/upb/bindings/lua/upb/pb.c
@@ -10,59 +10,24 @@
 
 #define LUPB_PBDECODERMETHOD "lupb.pb.decodermethod"
 
-#define MSGDEF_INDEX 1
-
-static upb_pbdecodermethod *lupb_pbdecodermethod_check(lua_State *L, int narg) {
-  return lupb_refcounted_check(L, narg, LUPB_PBDECODERMETHOD);
-}
-
-static int lupb_pbdecodermethod_new(lua_State *L) {
-  const upb_handlers *handlers = lupb_msg_newwritehandlers(L, 1, &handlers);
-  const upb_pbdecodermethod *m;
-
-  upb_pbdecodermethodopts opts;
-  upb_pbdecodermethodopts_init(&opts, handlers);
-
-  m = upb_pbdecodermethod_new(&opts, &m);
-  upb_handlers_unref(handlers, &handlers);
-  lupb_refcounted_pushnewrapper(
-      L, upb_pbdecodermethod_upcast(m), LUPB_PBDECODERMETHOD, &m);
-
-  /* We need to keep a pointer to the MessageDef (in Lua space) so we can
-   * construct new messages in parse(). */
-  lua_newtable(L);
-  lua_pushvalue(L, 1);
-  lua_rawseti(L, -2, MSGDEF_INDEX);
-  lua_setuservalue(L, -2);
-
-  return 1;  /* The DecoderMethod wrapper. */
-}
-
-/* Unlike most of our exposed Lua functions, this does not correspond to an
- * actual method on the underlying DecoderMethod.  But it's convenient, and
- * important to implement in C because we can do stack allocation and
- * initialization of our runtime structures like the Decoder and Sink. */
-static int lupb_pbdecodermethod_parse(lua_State *L) {
+static int lupb_pb_strtomessage(lua_State *L) {
   size_t len;
-  const upb_pbdecodermethod *method = lupb_pbdecodermethod_check(L, 1);
-  const char *pb = lua_tolstring(L, 2, &len);
-  void *msg;
   upb_status status = UPB_STATUS_INIT;
+  const char *pb = lua_tolstring(L, 1, &len);
+  const upb_msglayout *layout = lua_touserdata(L, lua_upvalueindex(1));
+  const upb_pbdecodermethod *method = lua_touserdata(L, lua_upvalueindex(2));
+  const upb_handlers *handlers = upb_pbdecodermethod_desthandlers(method);
+
+  upb_arena *msg_arena;
   upb_env env;
   upb_sink sink;
   upb_pbdecoder *decoder;
+  void *msg;
 
-  const upb_handlers *handlers = upb_pbdecodermethod_desthandlers(method);
-
-  lua_getuservalue(L, 1);
-  lua_rawgeti(L, -1, MSGDEF_INDEX);
-  lupb_assert(L, !lua_isnil(L, -1));
-  lupb_msg_pushnew(L, -1);  /* Push new message. */
-  msg = lua_touserdata(L, -1);
-
-  /* Handlers need this. */
-  lua_getuservalue(L, -1);
+  lupb_arena_new(L);
+  msg_arena = lupb_arena_check(L, -1);
 
+  msg = upb_msg_new(layout, upb_arena_alloc(msg_arena));
   upb_env_init(&env);
   upb_env_reporterrorsto(&env, &status);
   upb_sink_reset(&sink, handlers, msg);
@@ -76,18 +41,42 @@ static int lupb_pbdecodermethod_parse(lua_State *L) {
 
   lupb_checkstatus(L, &status);
 
-  lua_pop(L, 1);  /* Uservalue. */
-
+  /* References the arena at the top of the stack. */
+  lupb_msg_pushref(L, lua_upvalueindex(3), msg);
   return 1;
 }
 
-static const struct luaL_Reg lupb_pbdecodermethod_m[] = {
-  {"parse", lupb_pbdecodermethod_parse},
+static int lupb_pb_makestrtomsgdecoder(lua_State *L) {
+  const upb_msglayout *layout = lupb_msgclass_getlayout(L, 1);
+  const upb_handlers *handlers = lupb_msgclass_getmergehandlers(L, 1);
+  const upb_pbdecodermethod *m;
+
+  upb_pbdecodermethodopts opts;
+  upb_pbdecodermethodopts_init(&opts, handlers);
+
+  m = upb_pbdecodermethod_new(&opts, &m);
+
+  /* Push upvalues for the closure. */
+  lua_pushlightuserdata(L, (void*)layout);
+  lua_pushlightuserdata(L, (void*)m);
+  lua_pushvalue(L, 1);
+
+  /* Upvalue for the closure, only to keep the decodermethod alive. */
+  lupb_refcounted_pushnewrapper(
+      L, upb_pbdecodermethod_upcast(m), LUPB_PBDECODERMETHOD, &m);
+
+  lua_pushcclosure(L, &lupb_pb_strtomessage, 4);
+
+  return 1;  /* The decoder closure. */
+}
+
+static const struct luaL_Reg decodermethod_mm[] = {
+  {"__gc", lupb_refcounted_gc},
   {NULL, NULL}
 };
 
 static const struct luaL_Reg toplevel_m[] = {
-  {"DecoderMethod", lupb_pbdecodermethod_new},
+  {"MakeStringToMessageDecoder", lupb_pb_makestrtomsgdecoder},
   {NULL, NULL}
 };
 
@@ -97,8 +86,7 @@ int luaopen_upb_pb_c(lua_State *L) {
     return 1;
   }
 
-  lupb_register_type(L, LUPB_PBDECODERMETHOD, lupb_pbdecodermethod_m, NULL,
-                     true);
+  lupb_register_type(L, LUPB_PBDECODERMETHOD, NULL, decodermethod_mm);
 
   return 1;
 }