'cpcall' reimplemented as a predefined value in the registry

lapi.c

@@ -1,5 +1,5 @@
 /*
-** $Id: lapi.c,v 2.89 2009/08/31 14:26:28 roberto Exp roberto $
+** $Id: lapi.c,v 2.90 2009/09/17 18:04:21 roberto Exp roberto $
 ** Lua API
 ** See Copyright Notice in lua.h
 */
@@ -854,40 +854,6 @@ LUA_API int lua_pcallk (lua_State *L, int nargs, int nresults, int errfunc,
 }
 
 
-/*
-** Execute a protected C call.
-*/
-struct CCallS {  /* data to `f_Ccall' */
-  lua_CFunction func;
-  void *ud;
-};
-
-
-static void f_Ccall (lua_State *L, void *ud) {
-  struct CCallS *c = cast(struct CCallS *, ud);
-  Closure *cl;
-  cl = luaF_newCclosure(L, 0, getcurrenv(L));
-  cl->c.f = c->func;
-  setclvalue(L, L->top, cl);  /* push function */
-  api_incr_top(L);
-  setpvalue(L->top, c->ud);  /* push only argument */
-  api_incr_top(L);
-  luaD_call(L, L->top - 2, 0, 0);
-}
-
-
-LUA_API int lua_cpcall (lua_State *L, lua_CFunction func, void *ud) {
-  struct CCallS c;
-  int status;
-  lua_lock(L);
-  c.func = func;
-  c.ud = ud;
-  status = luaD_pcall(L, f_Ccall, &c, savestack(L, L->top), 0);
-  lua_unlock(L);
-  return status;
-}
-
-
 LUA_API int lua_load (lua_State *L, lua_Reader reader, void *data,
                       const char *chunkname) {
   ZIO z;
@@ -1113,3 +1079,11 @@ LUA_API const char *lua_setupvalue (lua_State *L, int funcindex, int n) {
   return name;
 }
 
+
+LUA_API int lua_cpcall (lua_State *L, lua_CFunction func, void *ud) {
+  lua_rawgeti(L, LUA_REGISTRYINDEX, LUA_RIDX_CPCALL);
+  lua_pushlightuserdata(L, &func);
+  lua_pushlightuserdata(L, ud);
+  return lua_pcall(L, 2, 0, 0);
+}
+

lstate.c

@@ -1,5 +1,5 @@
 /*
-** $Id: lstate.c,v 2.57 2009/07/15 17:26:14 roberto Exp roberto $
+** $Id: lstate.c,v 2.58 2009/09/17 18:04:21 roberto Exp roberto $
 ** Global State
 ** See Copyright Notice in lua.h
 */
@@ -91,18 +91,41 @@ static void freestack (lua_State *L) {
 }
 
 
+/*
+** Calls the function in variable pointed to by userdata in first argument
+** (Userdata cannot point directly to the function because pointer to
+** function is not compatible with void*.)
+*/
+static int cpcall (lua_State *L) {
+  lua_CFunction f = *(lua_CFunction *)lua_touserdata(L, 1);
+  lua_remove(L, 1);
+  return f(L);
+}
+
+
+/*
+** Create registry table and its predefined values
+*/
 static void init_registry (lua_State *L) {
-  Table *registry = luaH_new(L);
+  Closure *cp;
   TValue mt;
+  /* create registry */
+  Table *registry = luaH_new(L);
   sethvalue(L, registry(L), registry);
   luaH_resize(L, registry, LUA_RIDX_LAST, 0);
+  /* registry[LUA_RIDX_MAINTHREAD] = L */
   setthvalue(L, &mt, L);
   setobj2t(L, luaH_setint(L, registry, LUA_RIDX_MAINTHREAD), &mt);
+  /* registry[LUA_RIDX_CPCALL] = cpcall */
+  cp = luaF_newCclosure(L, 0, hvalue(gt(L)));
+  cp->c.f = cpcall;
+  setclvalue(L, &mt, cp);
+  setobj2t(L, luaH_setint(L, registry, LUA_RIDX_CPCALL), &mt);
 }
 
 
 /*
-** open parts that may cause memory-allocation errors
+** open parts of a state that may cause memory-allocation errors
 */
 static void f_luaopen (lua_State *L, void *ud) {
   global_State *g = G(L);
@@ -118,6 +141,10 @@ static void f_luaopen (lua_State *L, void *ud) {
 }
 
 
+/*
+** preinitialize a state with consistent values without allocating
+** any memory (to avoid errors)
+*/
 static void preinit_state (lua_State *L, global_State *g) {
   G(L) = g;
   L->stack = NULL;

lua.h

@@ -1,5 +1,5 @@
 /*
-** $Id: lua.h,v 1.242 2009/09/14 14:30:39 roberto Exp roberto $
+** $Id: lua.h,v 1.243 2009/09/17 18:04:21 roberto Exp roberto $
 ** Lua - An Extensible Extension Language
 ** Lua.org, PUC-Rio, Brazil (http://www.lua.org)
 ** See Copyright Notice at the end of this file
@@ -91,7 +91,8 @@ typedef void * (*lua_Alloc) (void *ud, void *ptr, size_t osize, size_t nsize);
 
 /* predefined values in the registry */
 #define LUA_RIDX_MAINTHREAD	1
-#define LUA_RIDX_LAST		LUA_RIDX_MAINTHREAD
+#define LUA_RIDX_CPCALL		2
+#define LUA_RIDX_LAST		LUA_RIDX_CPCALL