From d494733839e9cf6cb557462326ed21e7a58816c7 Mon Sep 17 00:00:00 2001
From: est31 <MTest31@outlook.com>
Date: Tue, 9 Feb 2016 07:08:31 +0100
Subject: Add minetest.register_lbm() to run code on block load only

---
 src/script/lua_api/l_env.cpp | 40 ++++++++++++++++++++++++++++++++++++++++
 src/script/lua_api/l_env.h   | 18 ++++++++++++++++++
 2 files changed, 58 insertions(+)

(limited to 'src/script/lua_api')

diff --git a/src/script/lua_api/l_env.cpp b/src/script/lua_api/l_env.cpp
index b445b1eb9..f4ddc2afc 100644
--- a/src/script/lua_api/l_env.cpp
+++ b/src/script/lua_api/l_env.cpp
@@ -90,6 +90,46 @@ void LuaABM::trigger(ServerEnvironment *env, v3s16 p, MapNode n,
 	lua_pop(L, 1); // Pop error handler
 }
 
+void LuaLBM::trigger(ServerEnvironment *env, v3s16 p, MapNode n)
+{
+	GameScripting *scriptIface = env->getScriptIface();
+	scriptIface->realityCheck();
+
+	lua_State *L = scriptIface->getStack();
+	sanity_check(lua_checkstack(L, 20));
+	StackUnroller stack_unroller(L);
+
+	int error_handler = PUSH_ERROR_HANDLER(L);
+
+	// Get registered_lbms
+	lua_getglobal(L, "core");
+	lua_getfield(L, -1, "registered_lbms");
+	luaL_checktype(L, -1, LUA_TTABLE);
+	lua_remove(L, -2); // Remove core
+
+	// Get registered_lbms[m_id]
+	lua_pushnumber(L, m_id);
+	lua_gettable(L, -2);
+	FATAL_ERROR_IF(lua_isnil(L, -1), "Entry with given id not found in registered_lbms table");
+	lua_remove(L, -2); // Remove registered_lbms
+
+	scriptIface->setOriginFromTable(-1);
+
+	// Call action
+	luaL_checktype(L, -1, LUA_TTABLE);
+	lua_getfield(L, -1, "action");
+	luaL_checktype(L, -1, LUA_TFUNCTION);
+	lua_remove(L, -2); // Remove registered_lbms[m_id]
+	push_v3s16(L, p);
+	pushnode(L, n, env->getGameDef()->ndef());
+
+	int result = lua_pcall(L, 2, 0, error_handler);
+	if (result)
+		scriptIface->scriptError(result, "LuaLBM::trigger");
+
+	lua_pop(L, 1); // Pop error handler
+}
+
 void LuaEmergeAreaCallback(v3s16 blockpos, EmergeAction action, void *param)
 {
 	ScriptCallbackState *state = (ScriptCallbackState *)param;
diff --git a/src/script/lua_api/l_env.h b/src/script/lua_api/l_env.h
index 4f8dfcd3c..0e385ffef 100644
--- a/src/script/lua_api/l_env.h
+++ b/src/script/lua_api/l_env.h
@@ -220,6 +220,24 @@ public:
 			u32 active_object_count, u32 active_object_count_wider);
 };
 
+class LuaLBM : public LoadingBlockModifierDef
+{
+private:
+	int m_id;
+public:
+	LuaLBM(lua_State *L, int id,
+			const std::set<std::string> &trigger_contents,
+			const std::string &name,
+			bool run_at_every_load):
+		m_id(id)
+	{
+		this->run_at_every_load = run_at_every_load;
+		this->trigger_contents = trigger_contents;
+		this->name = name;
+	}
+	virtual void trigger(ServerEnvironment *env, v3s16 p, MapNode n);
+};
+
 struct ScriptCallbackState {
 	GameScripting *script;
 	int callback_ref;
-- 
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