Towards a new implementation of arrays

The array part of a table wastes too much space, due to padding.
To avoid that, we need to store values in the array as something
different from a TValue. Therefore, the API for table access
should not assume that any value in a table lives in a *TValue.
This commit is the first step to remove that assumption: functions
luaH_get*, instead of returning a *TValue where the value lives,
receive a *TValue where to put the value being accessed.
(We still have to change the luaH_set* functions.)

ltable.c

@@ -752,6 +752,21 @@ const TValue *luaH_getint (Table *t, lua_Integer key) {
 }
 
 
+static int finishnodeget (const TValue *val, TValue *res) {
+  if (!ttisnil(val)) {
+    setobj(((lua_State*)NULL), res, val);
+    return HOK;  /* success */
+  }
+  else
+    return HNOTFOUND;  /* could not get value */
+}
+
+
+int luaH_getint1 (Table *t, lua_Integer key, TValue *res) {
+  return finishnodeget(luaH_getint(t, key), res);
+}
+
+
 /*
 ** search function for short strings
 */
@@ -771,6 +786,11 @@ const TValue *luaH_getshortstr (Table *t, TString *key) {
 }
 
 
+int luaH_getshortstr1 (Table *t, TString *key, TValue *res) {
+  return finishnodeget(luaH_getshortstr(t, key), res);
+}
+
+
 const TValue *luaH_getstr (Table *t, TString *key) {
   if (key->tt == LUA_VSHRSTR)
     return luaH_getshortstr(t, key);
@@ -782,6 +802,11 @@ const TValue *luaH_getstr (Table *t, TString *key) {
 }
 
 
+int luaH_getstr1 (Table *t, TString *key, TValue *res) {
+  return finishnodeget(luaH_getstr(t, key), res);
+}
+
+
 /*
 ** main search function
 */
@@ -802,6 +827,11 @@ const TValue *luaH_get (Table *t, const TValue *key) {
 }
 
 
+int luaH_get1 (Table *t, const TValue *key, TValue *res) {
+  return finishnodeget(luaH_get(t, key), res);
+}
+
+
 /*
 ** Finish a raw "set table" operation, where 'slot' is where the value
 ** should have been (the result of a previous "get table").