1 files changed, 119 insertions, 0 deletions
diff --git a/src/l52util.c b/src/l52util.c
new file mode 100644
index 0000000..5675114
--- /dev/null
+++ b/src/l52util.c
@@ -0,0 +1,119 @@
+#include "l52util.h"
+
+#include <memory.h>
+#include <assert.h>
+
+#if LUA_VERSION_NUM >= 502 
+
+int luaL_typerror (lua_State *L, int narg, const char *tname) {
+  const char *msg = lua_pushfstring(L, "%s expected, got %s", tname,
+      luaL_typename(L, narg));
+  return luaL_argerror(L, narg, msg);
+}
+
+void luaL_register (lua_State *L, const char *libname, const luaL_Reg *l){
+  if(libname) lua_newtable(L);
+  luaL_setfuncs(L, l, 0);
+}
+
+#else 
+
+void luaL_setfuncs (lua_State *L, const luaL_Reg *l, int nup){
+  luaL_checkstack(L, nup, "too many upvalues");
+  for (; l->name != NULL; l++) {  /* fill the table with given functions */
+    int i;
+    for (i = 0; i < nup; i++)  /* copy upvalues to the top */
+      lua_pushvalue(L, -nup);
+    lua_pushcclosure(L, l->func, nup);  /* closure with those upvalues */
+    lua_setfield(L, -(nup + 2), l->name);
+  }
+  lua_pop(L, nup);  /* remove upvalues */
+}
+
+void lua_rawgetp(lua_State *L, int index, const void *p){
+  index = lua_absindex(L, index);
+  lua_pushlightuserdata(L, (void *)p);
+  lua_rawget(L, index);
+}
+
+void lua_rawsetp (lua_State *L, int index, const void *p){
+  index = lua_absindex(L, index);
+  lua_pushlightuserdata(L, (void *)p);
+  lua_insert(L, -2);
+  lua_rawset(L, index);
+}
+
+#endif
+
+int lutil_newmetatablep (lua_State *L, const void *p) {
+  lua_rawgetp(L, LUA_REGISTRYINDEX, p);
+  if (!lua_isnil(L, -1))  /* name already in use? */
+    return 0;  /* leave previous value on top, but return 0 */
+  lua_pop(L, 1);
+
+  lua_newtable(L);  /* create metatable */
+  lua_pushvalue(L, -1); /* duplicate metatable to set*/
+  lua_rawsetp(L, LUA_REGISTRYINDEX, p);
+
+  return 1;
+}
+
+void lutil_getmetatablep (lua_State *L, const void *p) {
+  lua_rawgetp(L, LUA_REGISTRYINDEX, p);
+}
+
+void lutil_setmetatablep (lua_State *L, const void *p) {
+  lutil_getmetatablep(L, p);
+  assert(lua_istable(L,-1));
+  lua_setmetatable (L, -2);
+}
+
+int lutil_isudatap (lua_State *L, int ud, const void *p) {
+  if (lua_isuserdata(L, ud)){
+    if (lua_getmetatable(L, ud)) {           /* does it have a metatable? */
+      int res;
+      lutil_getmetatablep(L,p);              /* get correct metatable */
+      res = lua_rawequal(L, -1, -2);         /* does it have the correct mt? */
+      lua_pop(L, 2);                         /* remove both metatables */
+      return res;
+    }
+  }
+  return 0;
+}
+
+void *lutil_checkudatap (lua_State *L, int ud, const void *p) {
+  void *up = lua_touserdata(L, ud);
+  if (up != NULL) {                   /* value is a userdata? */
+    if (lua_getmetatable(L, ud)) {    /* does it have a metatable? */
+      lutil_getmetatablep(L,p);       /* get correct metatable */
+      if (lua_rawequal(L, -1, -2)) {  /* does it have the correct mt? */
+        lua_pop(L, 2);                /* remove both metatables */
+        return up;
+      }
+    }
+  }
+  luaL_typerror(L, ud, p);  /* else error */
+  return NULL;              /* to avoid warnings */
+}
+
+int lutil_createmetap (lua_State *L, const void *p, const luaL_Reg *methods) {
+  if (!lutil_newmetatablep(L, p))
+    return 0;
+
+  /* define methods */
+  luaL_setfuncs (L, methods, 0);
+
+  /* define metamethods */
+  lua_pushliteral (L, "__index");
+  lua_pushvalue (L, -2);
+  lua_settable (L, -3);
+
+  return 1;
+}
+
+void *lutil_newudatap_impl(lua_State *L, size_t size, const void *p){
+  void *obj = lua_newuserdata (L, size);
+  memset(obj, 0, size);
+  lutil_setmetatablep(L, p);
+  return obj;
+}