/**
* Generates a metatable containing metafunctions for a given object type using the currently
* registered {@link LuaObjectMeta}s.
*
* <p>This method will only generate one metatable per class type; the mapping of already made
* metatables will not be cleared at any point during runtime. If a metatable had already been
* generated, that metatable is returned.
*
* <p>It is possible for functions within each object meta to override each other when this method
* generates a new metatable.
*
* <p>If there are no suitable meta objects for the provided object or none of the applicable meta
* objects have any metafunctions to register, null is returned.
*
* @param obj the Object to generate a metatable for
* @return the metatable for the given Object
*/
public static LuaTable generateMetatable(Object obj) {
LuaTable copyTable = Lua.METATABLES.get(obj.getClass());
if (copyTable == null && copyTable != Lua.EMPTY_METATABLE) {
LuaTable functable = new LuaTable();
Lua.metas.clear();
Lua.META.values().forEach(Lua.metas::add);
Lua.PMETA.values().forEach(Lua.metas::add);
Lua.metas.forEach(
meta -> {
if (meta.getTargetObjectClass().isInstance(obj) && meta.getMetatable() != null) {
LuaUtil.iterateTable(
meta.getMetatable(),
vargs -> {
functable.set(vargs.arg(1), vargs.arg(2));
});
}
});
Lua.metas.forEach(
meta -> {
meta.postMetaInit(functable);
});
if (LuaUtil.getTableSize(functable) > 0) {
LuaTable metatable = new LuaTable();
// add the object's metatable functions
metatable.set("__index", functable);
// add the stuff we do for every metatable
GLOBAL_METATABLE
.entries()
.forEach(
entry -> {
metatable.set(entry.key, entry.value);
});
Lua.METATABLES.put(obj.getClass(), metatable);
copyTable = metatable;
} else {
Lua.METATABLES.put(obj.getClass(), Lua.EMPTY_METATABLE);
}
}
if (copyTable != null && copyTable != Lua.EMPTY_METATABLE) {
return LuaUtil.copyTable(copyTable, true);
}
return null;
}
