/**
* 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;
}
/**
* Internal method.
*
* <p>Returns a stored {@link LuaObjectMeta} instance.
*/
static LuaObjectMeta getMeta(Class<? extends LuaObjectMeta> metaClass) {
for (LuaObjectMeta meta : Lua.PMETA.values()) {
if (meta.getClass() == metaClass) {
return meta;
}
}
for (LuaObjectMeta meta : Lua.META.values()) {
if (meta.getClass() == metaClass) {
return meta;
}
}
return null;
}
/**
* Returns the {@link LuaObjectMeta} registered with the provided typename.
*
* @param metaName the typename to match
* @return the LuaObjectMeta matching the given typename, or null if doesn't exist
*/
public static LuaObjectMeta getMeta(String metaName) {
for (LuaObjectMeta meta : Lua.PMETA.values()) {
if (meta.getTypeName().equals(metaName)) {
return meta;
}
}
for (LuaObjectMeta meta : Lua.META.values()) {
if (meta.getTypeName().equals(metaName)) {
return meta;
}
}
return null;
}
/**
* Returns the {@link LuaObjectMeta} associated with the provided object.
*
* <p>If the provided object is an instance of {@link LuaImplementable} and has a primary
* identifying class, the meta associated with that class is scanned for first.
*
* @param obj the Object to query with
* @return the LuaObjectMeta associated with the provided object, or null if one was not found
*/
public static LuaObjectMeta getMeta(Object obj) {
if (obj == null) {
return null;
}
Class<?> target = null;
if (obj instanceof LuaImplementable
&& ((LuaImplementable<?>) obj).getPrimaryIdentifyingClass() != null) {
target = ((LuaImplementable<?>) obj).getPrimaryIdentifyingClass();
} else {
target = obj.getClass();
}
do {
if (Lua.PMETA.containsKey(target)) {
return Lua.PMETA.get(target);
}
if (Lua.META.containsKey(target)) {
return Lua.META.get(target);
}
for (LuaObjectMeta meta : Lua.PMETA.values()) {
if (meta.getTargetObjectClass().isInstance(obj)) {
return meta;
}
}
for (LuaObjectMeta meta : Lua.META.values()) {
if (meta.getTargetObjectClass().isInstance(obj)) {
return meta;
}
}
if (target != obj.getClass()) {
target = obj.getClass();
} else {
target = null;
}
} while (target != null);
return null;
}
/**
* Injects all registered metatables into the provided table, with the owning meta's typename as
* their keys.
*
* <p>Should only be used by {@link MetaLib}.
*/
public static void injectMetatables(LuaTable table) {
Lua.PMETA
.values()
.forEach(
meta -> {
if (meta.getMetatable() != null) {
table.set(meta.getTypeName(), meta.getMetatable());
}
});
Lua.META
.values()
.forEach(
meta -> {
if (meta.getMetatable() != null) {
table.set(meta.getTypeName(), meta.getMetatable());
}
});
}