new function 'table.maxn'

ltablib.c

@@ -1,5 +1,5 @@
 /*
-** $Id: ltablib.c,v 1.34 2005/08/15 14:12:32 roberto Exp roberto $
+** $Id: ltablib.c,v 1.35 2005/08/26 17:36:32 roberto Exp roberto $
 ** Library for Table Manipulation
 ** See Copyright Notice in lua.h
 */
@@ -40,9 +40,7 @@ static int foreach (lua_State *L) {
   luaL_checktype(L, 1, LUA_TTABLE);
   luaL_checktype(L, 2, LUA_TFUNCTION);
   lua_pushnil(L);  /* first key */
-  for (;;) {
-    if (lua_next(L, 1) == 0)
-      return 0;
+  while (lua_next(L, 1)) {
     lua_pushvalue(L, 2);  /* function */
     lua_pushvalue(L, -3);  /* key */
     lua_pushvalue(L, -3);  /* value */
@@ -51,6 +49,23 @@ static int foreach (lua_State *L) {
       return 1;
     lua_pop(L, 2);  /* remove value and result */
   }
+  return 0;
+}
+
+
+static int maxn (lua_State *L) {
+  lua_Number max = 0;
+  luaL_checktype(L, 1, LUA_TTABLE);
+  lua_pushnil(L);  /* first key */
+  while (lua_next(L, 1)) {
+    lua_pop(L, 1);  /* remove value */
+    if (lua_type(L, -1) == LUA_TNUMBER) {
+      lua_Number v = lua_tonumber(L, -1);
+      if (v > max) max = v;
+    }
+  }
+  lua_pushnumber(L, max);
+  return 1;
 }
 
 
@@ -241,6 +256,7 @@ static const luaL_Reg tab_funcs[] = {
   {"foreach", foreach},
   {"foreachi", foreachi},
   {"getn", getn},
+  {"maxn", maxn},
   {"insert", tinsert},
   {"remove", tremove},
   {"setn", setn},