New API function 'lua_closeslot'

Closing a to-be-closed variable with 'lua_settop' is too restrictive,
as it erases all slots above the variable. Moreover, it adds side
effects to 'lua_settop', which should be a fairly basic function.

1 files changed, 3 insertions, 5 deletions

diff --git a/lauxlib.c b/lauxlib.c
index 074ff08c..e8fc486e 100644
--- a/lauxlib.c
+++ b/lauxlib.c
@@ -545,10 +545,8 @@ static char *prepbuffsize (luaL_Buffer *B, size_t sz, int boxidx) {
     if (buffonstack(B))  /* buffer already has a box? */
       newbuff = (char *)resizebox(L, boxidx, newsize);  /* resize it */
     else {  /* no box yet */
-      lua_pushnil(L);  /* reserve slot for final result */
       newbox(L);  /* create a new box */
-      /* move box (and slot) to its intended position */
-      lua_rotate(L, boxidx - 1, 2);
+      lua_insert(L, boxidx);  /* move box to its intended position */
       lua_toclose(L, boxidx);
       newbuff = (char *)resizebox(L, boxidx, newsize);
       memcpy(newbuff, B->b, B->n * sizeof(char));  /* copy original content */
@@ -585,8 +583,8 @@ LUALIB_API void luaL_pushresult (luaL_Buffer *B) {
   lua_State *L = B->L;
   lua_pushlstring(L, B->b, B->n);
   if (buffonstack(B)) {
-    lua_copy(L, -1, -3);  /* move string to reserved slot */
-    lua_pop(L, 2);  /* pop string and box (closing the box) */
+    lua_closeslot(L, -2);  /* close the box */
+    lua_remove(L, -2);  /* remove box from the stack */
   }
 }