commit 0f1f51be4b1e2fb561b2ec6dce7fe292d5b3764d
parent ee5edb6b680589805c8fc348f6a7566c2bd8735d
Author: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Thu, 17 Sep 2015 12:53:24 -0300
'table.move' tries to copy elements in increasing order
whenever possible
Diffstat:
1 file changed, 10 insertions(+), 4 deletions(-)
diff --git a/ltablib.c b/ltablib.c
@@ -1,5 +1,5 @@
/*
-** $Id: ltablib.c,v 1.81 2015/07/04 16:31:42 roberto Exp roberto $
+** $Id: ltablib.c,v 1.82 2015/09/09 15:42:30 roberto Exp roberto $
** Library for Table Manipulation
** See Copyright Notice in lua.h
*/
@@ -118,6 +118,12 @@ static int tremove (lua_State *L) {
}
+/*
+** Copy elements (1[f], ..., 1[e]) into (tt[t], tt[t+1], ...). Whenever
+** possible, copy in increasing order, which is better for rehashing.
+** "possible" means destination after original range, or smaller
+** than origin, or copying to another table.
+*/
static int tmove (lua_State *L) {
lua_Integer f = luaL_checkinteger(L, 2);
lua_Integer e = luaL_checkinteger(L, 3);
@@ -132,14 +138,14 @@ static int tmove (lua_State *L) {
n = e - f + 1; /* number of elements to move */
luaL_argcheck(L, t <= LUA_MAXINTEGER - n + 1, 4,
"destination wrap around");
- if (t > f) {
- for (i = n - 1; i >= 0; i--) {
+ if (t > e || t <= f || tt != 1) {
+ for (i = 0; i < n; i++) {
lua_geti(L, 1, f + i);
lua_seti(L, tt, t + i);
}
}
else {
- for (i = 0; i < n; i++) {
+ for (i = n - 1; i >= 0; i--) {
lua_geti(L, 1, f + i);
lua_seti(L, tt, t + i);
}