snapshot

Not quite working. curses.stdscr() is returning userdata, not a window.

This is true even of the raw array example from the book. So we need to
learn something new here. How does lcurses's Pinitscr return a special
window object? From what I can tell it's just putting the results of
lc_newwin() on the stack. Which is the same as my curses_newwin() here.

src/lcurseslib.c

@@ -1,19 +1,20 @@
 #include <ncurses.h>
 
 #include "lua.h"
+#include "llimits.h"
 
 #include "lauxlib.h"
 #include "lualib.h"
 
 
-static int Pstdscr(lua_State *L) {
+static int Pstdscr (lua_State *L) {
   lua_pushstring(L, "curses:stdscr");
   lua_rawget(L, LUA_REGISTRYINDEX);
   return 1;
 }
 
 
-static int Pcols(lua_State *L) {
+static int Pcols (lua_State *L) {
   lua_pushinteger(L, COLS);
   return 1;
 }
@@ -40,7 +41,65 @@ static void curses_newwin (lua_State *L, WINDOW *nw) {
 }
 
 
+static WINDOW **lc_getwin (lua_State *L, int offset) {
+	WINDOW **w = (WINDOW**)luaL_checkudata(L, offset, "meta.window");
+	if (w == NULL)
+		luaL_argerror(L, offset, "bad curses window");
+	return w;
+}
+
+
+static WINDOW *checkwin (lua_State *L, int offset) {
+  WINDOW **w = lc_getwin(L, offset);
+  if (*w == NULL)
+    luaL_argerror(L, offset, "attempt to use closed curses window");
+  return *w;
+}
+
+
+static int
+argtypeerror(lua_State *L, int narg, const char *expected)
+{
+	const char *got = luaL_typename(L, narg);
+	return luaL_argerror(L, narg,
+		lua_pushfstring(L, "%s expected, got %s", expected, got));
+}
+
+
+static lua_Integer checkinteger (lua_State *L, int narg, const char *expected) {
+  lua_Integer d = lua_tointeger(L, narg);
+  if (d == 0 && !lua_isnumber(L, narg))
+    argtypeerror(L, narg, expected);
+  return d;
+}
+
+
+static int optint (lua_State *L, int narg, lua_Integer def) {
+  if (lua_isnoneornil(L, narg))
+    return cast(int, def);
+  return cast(int, checkinteger(L, narg, "int or nil"));
+}
+
+
+static int Waddstr (lua_State *L) {
+  WINDOW *w = checkwin(L, 1);
+  const char *str = luaL_checkstring(L, 2);
+  int n = optint(L, 3, -1);
+  lua_pushboolean(L, waddnstr(w, str, n));
+  return 1;
+}
+
+
+static const luaL_Reg curses_window_methods[] =
+{
+  {"addstr", Waddstr},
+  {NULL, NULL}
+};
+
+
 LUALIB_API int luaopen_curses (lua_State *L) {
+  luaL_newmetatable(L, "meta.window");
+  luaL_register(L, NULL, curses_window_methods);
   luaL_register(L, "curses", curseslib);
   /* save main window on registry */
   curses_newwin(L, stdscr);