From 2341a4aff1242e978d6fad3772d4d4fb015c040d Mon Sep 17 00:00:00 2001
From: Zughy <63455151+Zughy@users.noreply.github.com>
Date: Tue, 13 Oct 2020 21:27:52 +0200
Subject: [PATCH] Add ObjectRef:get_children() (#10480)

Co-authored-by: Zughy <4279489-marco_a@users.noreply.gitlab.com>
---
 doc/lua_api.txt                 |  2 ++
 src/script/lua_api/l_object.cpp | 22 ++++++++++++++++++++++
 src/script/lua_api/l_object.h   |  3 +++
 3 files changed, 27 insertions(+)

diff --git a/doc/lua_api.txt b/doc/lua_api.txt
index c8b294149..1631d564c 100644
--- a/doc/lua_api.txt
+++ b/doc/lua_api.txt
@@ -6206,6 +6206,8 @@ object you are working with still exists.
        should appear in first person.
 * `get_attach()`: returns parent, bone, position, rotation, forced_visible, 
     or nil if it isn't attached.
+* `get_children()`: returns a list of ObjectRefs that are attached to the
+    object.
 * `set_detach()`
 * `set_bone_position(bone, position, rotation)`
     * `bone`: string
diff --git a/src/script/lua_api/l_object.cpp b/src/script/lua_api/l_object.cpp
index 57ed7e2cd..96c8c687c 100644
--- a/src/script/lua_api/l_object.cpp
+++ b/src/script/lua_api/l_object.cpp
@@ -738,6 +738,27 @@ int ObjectRef::l_get_attach(lua_State *L)
 	return 5;
 }
 
+// get_children(self)
+int ObjectRef::l_get_children(lua_State *L)
+{
+	GET_ENV_PTR;
+
+	ObjectRef *ref = checkobject(L, 1);
+	ServerActiveObject *sao = getobject(ref);
+	if (sao == nullptr)
+		return 0;
+
+	const std::unordered_set<int> child_ids = sao->getAttachmentChildIds();
+	int i = 0;
+	lua_createtable(L, child_ids.size(), 0);
+	for (const int id : child_ids) {
+		ServerActiveObject *child = env->getActiveObject(id);
+		getScriptApiBase(L)->objectrefGetOrCreate(L, child);
+		lua_rawseti(L, -2, ++i);
+	}
+	return 1;
+}
+
 // set_detach(self)
 int ObjectRef::l_set_detach(lua_State *L)
 {
@@ -2337,6 +2358,7 @@ luaL_Reg ObjectRef::methods[] = {
 	luamethod(ObjectRef, get_bone_position),
 	luamethod(ObjectRef, set_attach),
 	luamethod(ObjectRef, get_attach),
+	luamethod(ObjectRef, get_children),
 	luamethod(ObjectRef, set_detach),
 	luamethod(ObjectRef, set_properties),
 	luamethod(ObjectRef, get_properties),
diff --git a/src/script/lua_api/l_object.h b/src/script/lua_api/l_object.h
index ca03dfa2e..097a74cae 100644
--- a/src/script/lua_api/l_object.h
+++ b/src/script/lua_api/l_object.h
@@ -143,6 +143,9 @@ private:
 	// get_attach(self)
 	static int l_get_attach(lua_State *L);
 
+	// get_children(self)
+	static int l_get_children(lua_State *L);
+
 	// set_detach(self)
 	static int l_set_detach(lua_State *L);