util.table: Backport table.move() from Lua 5.4

One difference is that 5.4 accepts "table-like" values (for this and other
table.*() functions), but that would require additional backporting work.

1 files changed, 42 insertions, 0 deletions

diff --git a/util-src/table.c b/util-src/table.c
index 9a9553fc..0756a256 100644
--- a/util-src/table.c
+++ b/util-src/table.c
@@ -1,11 +1,17 @@
 #include <lua.h>
 #include <lauxlib.h>
 
+#ifndef LUA_MAXINTEGER
+#include <stdint.h>
+#define LUA_MAXINTEGER PTRDIFF_MAX
+#endif
+
 static int Lcreate_table(lua_State *L) {
 	lua_createtable(L, luaL_checkinteger(L, 1), luaL_checkinteger(L, 2));
 	return 1;
 }
 
+/* COMPAT: w/ Lua pre-5.4 */
 static int Lpack(lua_State *L) {
 	unsigned int n_args = lua_gettop(L);
 	lua_createtable(L, n_args, 1);
@@ -20,6 +26,40 @@ static int Lpack(lua_State *L) {
 	return 1;
 }
 
+/* COMPAT: w/ Lua pre-5.4 */
+static int Lmove (lua_State *L) {
+	lua_Integer f = luaL_checkinteger(L, 2);
+	lua_Integer e = luaL_checkinteger(L, 3);
+	lua_Integer t = luaL_checkinteger(L, 4);
+
+	int tt = !lua_isnoneornil(L, 5) ? 5 : 1;  /* destination table */
+	luaL_checktype(L, 1, LUA_TTABLE);
+	luaL_checktype(L, tt, LUA_TTABLE);
+
+	if (e >= f) {  /* otherwise, nothing to move */
+		lua_Integer n, i;
+		luaL_argcheck(L, f > 0 || e < LUA_MAXINTEGER + f, 3,
+		  "too many elements to move");
+		n = e - f + 1;  /* number of elements to move */
+		luaL_argcheck(L, t <= LUA_MAXINTEGER - n + 1, 4,
+		"destination wrap around");
+		if (t > e || t <= f || (tt != 1 && !lua_compare(L, 1, tt, LUA_OPEQ))) {
+			for (i = 0; i < n; i++) {
+				lua_rawgeti(L, 1, f + i);
+				lua_rawseti(L, tt, t + i);
+			}
+		} else {
+			for (i = n - 1; i >= 0; i--) {
+				lua_rawgeti(L, 1, f + i);
+				lua_rawseti(L, tt, t + i);
+			}
+		}
+	}
+
+	lua_pushvalue(L, tt);  /* return destination table */
+	return 1;
+}
+
 int luaopen_util_table(lua_State *L) {
 #if (LUA_VERSION_NUM > 501)
 	luaL_checkversion(L);
@@ -29,5 +69,7 @@ int luaopen_util_table(lua_State *L) {
 	lua_setfield(L, -2, "create");
 	lua_pushcfunction(L, Lpack);
 	lua_setfield(L, -2, "pack");
+	lua_pushcfunction(L, Lmove);
+	lua_setfield(L, -2, "move");
 	return 1;
 }