new metamethods for '__pairs' and '__ipairs'

lbaselib.c

@@ -1,5 +1,5 @@
 /*
-** $Id: lbaselib.c,v 1.197 2007/02/09 12:40:21 roberto Exp roberto $
+** $Id: lbaselib.c,v 1.198 2007/06/21 13:48:04 roberto Exp roberto $
 ** Basic library
 ** See Copyright Notice in lua.h
 */
@@ -223,6 +223,22 @@ static int luaB_type (lua_State *L) {
 }
 
 
+static int pairsmeta (lua_State *L, const char *method, int iszero) {
+  if (!luaL_getmetafield(L, 1, method)) {  /* no metamethod? */
+    luaL_checktype(L, 1, LUA_TTABLE);  /* argument must be a table */
+    lua_pushvalue(L, lua_upvalueindex(1));  /* will return generator, */
+    lua_pushvalue(L, 1);  /* state, */
+    if (iszero) lua_pushinteger(L, 0);  /* and initial value */
+    else lua_pushnil(L);
+  }
+  else {
+    lua_pushvalue(L, 1);  /* argument 'self' to metamethod */
+    lua_call(L, 1, 3);  /* get 3 values from metamethod */
+  }
+  return 3;
+}
+
+
 static int luaB_next (lua_State *L) {
   luaL_checktype(L, 1, LUA_TTABLE);
   lua_settop(L, 2);  /* create a 2nd argument if there isn't one */
@@ -236,11 +252,7 @@ static int luaB_next (lua_State *L) {
 
 
 static int luaB_pairs (lua_State *L) {
-  luaL_checktype(L, 1, LUA_TTABLE);
-  lua_pushvalue(L, lua_upvalueindex(1));  /* return generator, */
-  lua_pushvalue(L, 1);  /* state, */
-  lua_pushnil(L);  /* and initial value */
-  return 3;
+  return pairsmeta(L, "__pairs", 0);
 }
 
 
@@ -255,11 +267,7 @@ static int ipairsaux (lua_State *L) {
 
 
 static int luaB_ipairs (lua_State *L) {
-  luaL_checktype(L, 1, LUA_TTABLE);
-  lua_pushvalue(L, lua_upvalueindex(1));  /* return generator, */
-  lua_pushvalue(L, 1);  /* state, */
-  lua_pushinteger(L, 0);  /* and initial value */
-  return 3;
+  return pairsmeta(L, "__ipairs", 1);
 }