Intial commit

src/luaobj.c

@@ -0,0 +1,92 @@
+/** 
+ * Copyright (c) 2014 rxi
+ *
+ * This library is free software; you can redistribute it and/or modify it
+ * under the terms of the MIT license. See LICENSE for details.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "luaobj.h"
+
+
+int luaobj_newclass(lua_State *L, const char *name, const char *extends, 
+                    int (*constructor)(lua_State*), luaL_Reg* reg
+) {
+  /* Creates and pushes a new metatable which represents a class containing the
+   * functions in the `reg` argument. If the `extends` argument is not NULL
+   * this class will use the specified class as a super class */
+
+  /* Build metatable */ 
+  luaL_newmetatable(L, name);
+  /* Add type name string */
+  lua_pushstring(L, "__type");
+  lua_pushstring(L, name);
+  lua_rawset(L, -3);
+  /* Make and add func table */
+  lua_newtable(L);
+  luaL_setfuncs(L, reg, 0); 
+  lua_pushstring(L, "__index");
+  lua_pushvalue(L, -2);
+  lua_rawset(L, -4);
+  /* Handle extended */
+  if (extends) {
+    luaL_getmetatable(L, extends);
+    /* Pull metatable functions from base class */
+    char *mtfields[] = { "__gc", "__tostring", NULL };
+    int i;
+    for (i = 0; mtfields[i]; i++) {
+      lua_getfield(L, -1, mtfields[i]);
+      lua_setfield(L, -4, mtfields[i]);
+    }
+    lua_setmetatable(L, -2);
+  }
+  lua_pop(L, 1);              /* Pop func table */
+  luaL_setfuncs(L, reg, 0);   /* Set metatable's funcs */
+  lua_pop(L, 1);              /* Pop metatable */
+
+  /* Return constructor */
+  lua_pushcfunction(L, constructor);
+
+  return 1;
+}
+
+
+void luaobj_setclass(lua_State *L, uint32_t type, char *name) {
+  /* Sets the the metatable of the member at the top of the stack to the
+   * class-metatable of the given `name` */
+  luaobj_head_t *udata = lua_touserdata(L, -1);
+  udata->type = type;
+  luaL_getmetatable(L, name);
+  if (lua_isnil(L, -1)) {
+    luaL_error(
+      L, "missing metatable: assure class '%s' is inited in love.c\n", name);
+  }
+  lua_setmetatable(L, -2);
+}
+
+
+void *luaobj_newudata(lua_State *L, int size) {
+  /* Creates a udata of the requested size, plus space for the luaobj_head_t
+   * header. Returns the pointer to the udata's body */
+  int s = size + sizeof(luaobj_head_t);
+  luaobj_head_t *udata = lua_newuserdata(L, s);
+  udata->type = 0;
+  return udata + 1;
+}
+
+
+void *luaobj_checkudata(lua_State *L, int index, uint32_t type) {
+  /* Checks the header of a luaobj udata at the given index, taking into
+   * account super-classes it may have extended. Returns the udata's body if
+   * it is of the correct class, else errors out */
+  index = lua_absindex(L, index);
+  luaobj_head_t *udata = lua_touserdata(L, index);
+  if (!udata || !(udata->type & type)) {
+    luaL_argerror(L, index, "bad type");
+  }
+  return udata + 1;
+}
+