Modernize lua read (part 2 & 3): C++ templating assurance (#7410)

* Modernize lua read (part 2 & 3): C++ templating assurance

Implement the boolean reader
Implement the string reader
Also remove unused & unimplemented script_error_handler
Add a reader with default value

9 files changed, 29 insertions, 33 deletions

diff --git a/src/script/cpp_api/s_base.cpp b/src/script/cpp_api/s_base.cpp
index 54ff8c495..293c774b0 100644
--- a/src/script/cpp_api/s_base.cpp
+++ b/src/script/cpp_api/s_base.cpp
@@ -133,7 +133,7 @@ int ScriptApiBase::luaPanic(lua_State *L)
 {
 	std::ostringstream oss;
 	oss << "LUA PANIC: unprotected error in call to Lua API ("
-		<< lua_tostring(L, -1) << ")";
+		<< readParam<std::string>(L, -1) << ")";
 	FATAL_ERROR(oss.str().c_str());
 	// NOTREACHED
 	return 0;
@@ -184,7 +184,7 @@ void ScriptApiBase::loadScript(const std::string &script_path)
 	}
 	ok = ok && !lua_pcall(L, 0, 0, error_handler);
 	if (!ok) {
-		std::string error_msg = lua_tostring(L, -1);
+		std::string error_msg = readParam<std::string>(L, -1);
 		lua_pop(L, 2); // Pop error message and error handler
 		throw ModError("Failed to load and run script from " +
 				script_path + ":\n" + error_msg);
@@ -286,10 +286,10 @@ void ScriptApiBase::stackDump(std::ostream &o)
 		int t = lua_type(m_luastack, i);
 		switch (t) {
 			case LUA_TSTRING:  /* strings */
-				o << "\"" << lua_tostring(m_luastack, i) << "\"";
+				o << "\"" << readParam<std::string>(m_luastack, i) << "\"";
 				break;
 			case LUA_TBOOLEAN:  /* booleans */
-				o << (lua_toboolean(m_luastack, i) ? "true" : "false");
+				o << (readParam<bool>(m_luastack, i) ? "true" : "false");
 				break;
 			case LUA_TNUMBER:  /* numbers */ {
 				char buf[10];
diff --git a/src/script/cpp_api/s_base.h b/src/script/cpp_api/s_base.h
index 6f61b6b84..697e5f556 100644
--- a/src/script/cpp_api/s_base.h
+++ b/src/script/cpp_api/s_base.h
@@ -24,6 +24,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include <thread>
 #include <mutex>
 #include <unordered_map>
+#include "common/helper.h"
 #include "util/basic_macros.h"
 
 extern "C" {
@@ -74,7 +75,7 @@ class GUIEngine;
 class ServerActiveObject;
 struct PlayerHPChangeReason;
 
-class ScriptApiBase {
+class ScriptApiBase : protected LuaHelper {
 public:
 	ScriptApiBase(ScriptingType type);
 	// fake constructor to allow script API classes (e.g ScriptApiEnv) to virtually inherit from this one.
diff --git a/src/script/cpp_api/s_client.cpp b/src/script/cpp_api/s_client.cpp
index 7be4fc6a9..597883c2f 100644
--- a/src/script/cpp_api/s_client.cpp
+++ b/src/script/cpp_api/s_client.cpp
@@ -57,8 +57,7 @@ bool ScriptApiClient::on_sending_message(const std::string &message)
 	// Call callbacks
 	lua_pushstring(L, message.c_str());
 	runCallbacks(1, RUN_CALLBACKS_MODE_OR_SC);
-	bool ate = lua_toboolean(L, -1);
-	return ate;
+	return readParam<bool>(L, -1);
 }
 
 bool ScriptApiClient::on_receiving_message(const std::string &message)
@@ -71,8 +70,7 @@ bool ScriptApiClient::on_receiving_message(const std::string &message)
 	// Call callbacks
 	lua_pushstring(L, message.c_str());
 	runCallbacks(1, RUN_CALLBACKS_MODE_OR_SC);
-	bool ate = lua_toboolean(L, -1);
-	return ate;
+	return readParam<bool>(L, -1);
 }
 
 void ScriptApiClient::on_damage_taken(int32_t damage_amount)
@@ -186,8 +184,7 @@ bool ScriptApiClient::on_punchnode(v3s16 p, MapNode node)
 
 	// Call functions
 	runCallbacks(2, RUN_CALLBACKS_MODE_OR);
-	bool blocked = lua_toboolean(L, -1);
-	return blocked;
+	return readParam<bool>(L, -1);
 }
 
 bool ScriptApiClient::on_placenode(const PointedThing &pointed, const ItemDefinition &item)
@@ -204,7 +201,7 @@ bool ScriptApiClient::on_placenode(const PointedThing &pointed, const ItemDefini
 
 	// Call functions
 	runCallbacks(2, RUN_CALLBACKS_MODE_OR);
-	return lua_toboolean(L, -1);
+	return readParam<bool>(L, -1);
 }
 
 bool ScriptApiClient::on_item_use(const ItemStack &item, const PointedThing &pointed)
@@ -221,7 +218,7 @@ bool ScriptApiClient::on_item_use(const ItemStack &item, const PointedThing &poi
 
 	// Call functions
 	runCallbacks(2, RUN_CALLBACKS_MODE_OR);
-	return lua_toboolean(L, -1);
+	return readParam<bool>(L, -1);
 }
 
 bool ScriptApiClient::on_inventory_open(Inventory *inventory)
@@ -242,7 +239,7 @@ bool ScriptApiClient::on_inventory_open(Inventory *inventory)
 	}
 
 	runCallbacks(1, RUN_CALLBACKS_MODE_OR);
-	return lua_toboolean(L, -1);
+	return readParam<bool>(L, -1);
 }
 
 void ScriptApiClient::setEnv(ClientEnvironment *env)
diff --git a/src/script/cpp_api/s_entity.cpp b/src/script/cpp_api/s_entity.cpp
index 88dbcc620..a3f7fa68b 100644
--- a/src/script/cpp_api/s_entity.cpp
+++ b/src/script/cpp_api/s_entity.cpp
@@ -257,7 +257,7 @@ bool ScriptApiEntity::luaentity_Punch(u16 id,
 	setOriginFromTable(object);
 	PCALL_RES(lua_pcall(L, 6, 1, error_handler));
 
-	bool retval = lua_toboolean(L, -1);
+	bool retval = readParam<bool>(L, -1);
 	lua_pop(L, 2); // Pop object and error handler
 	return retval;
 }
@@ -287,7 +287,7 @@ bool ScriptApiEntity::luaentity_run_simple_callback(u16 id,
 	setOriginFromTable(object);
 	PCALL_RES(lua_pcall(L, 2, 1, error_handler));
 
-	bool retval = lua_toboolean(L, -1);
+	bool retval = readParam<bool>(L, -1);
 	lua_pop(L, 2); // Pop object and error handler
 	return retval;
 }
diff --git a/src/script/cpp_api/s_env.cpp b/src/script/cpp_api/s_env.cpp
index c9b652096..f8cef98b7 100644
--- a/src/script/cpp_api/s_env.cpp
+++ b/src/script/cpp_api/s_env.cpp
@@ -116,12 +116,12 @@ void ScriptApiEnv::initializeEnvironment(ServerEnvironment *env)
 			while (lua_next(L, table)) {
 				// key at index -2 and value at index -1
 				luaL_checktype(L, -1, LUA_TSTRING);
-				trigger_contents.emplace_back(lua_tostring(L, -1));
+				trigger_contents.emplace_back(readParam<std::string>(L, -1));
 				// removes value, keeps key for next iteration
 				lua_pop(L, 1);
 			}
 		} else if (lua_isstring(L, -1)) {
-			trigger_contents.emplace_back(lua_tostring(L, -1));
+			trigger_contents.emplace_back(readParam<std::string>(L, -1));
 		}
 		lua_pop(L, 1);
 
@@ -133,12 +133,12 @@ void ScriptApiEnv::initializeEnvironment(ServerEnvironment *env)
 			while (lua_next(L, table)) {
 				// key at index -2 and value at index -1
 				luaL_checktype(L, -1, LUA_TSTRING);
-				required_neighbors.emplace_back(lua_tostring(L, -1));
+				required_neighbors.emplace_back(readParam<std::string>(L, -1));
 				// removes value, keeps key for next iteration
 				lua_pop(L, 1);
 			}
 		} else if (lua_isstring(L, -1)) {
-			required_neighbors.emplace_back(lua_tostring(L, -1));
+			required_neighbors.emplace_back(readParam<std::string>(L, -1));
 		}
 		lua_pop(L, 1);
 
@@ -185,12 +185,12 @@ void ScriptApiEnv::initializeEnvironment(ServerEnvironment *env)
 			while (lua_next(L, table)) {
 				// key at index -2 and value at index -1
 				luaL_checktype(L, -1, LUA_TSTRING);
-				trigger_contents.insert(lua_tostring(L, -1));
+				trigger_contents.insert(readParam<std::string>(L, -1));
 				// removes value, keeps key for next iteration
 				lua_pop(L, 1);
 			}
 		} else if (lua_isstring(L, -1)) {
-			trigger_contents.insert(lua_tostring(L, -1));
+			trigger_contents.insert(readParam<std::string>(L, -1));
 		}
 		lua_pop(L, 1);
 
diff --git a/src/script/cpp_api/s_node.cpp b/src/script/cpp_api/s_node.cpp
index 11c08811f..719f53a6b 100644
--- a/src/script/cpp_api/s_node.cpp
+++ b/src/script/cpp_api/s_node.cpp
@@ -192,7 +192,7 @@ bool ScriptApiNode::node_on_flood(v3s16 p, MapNode node, MapNode newnode)
 	pushnode(L, newnode, ndef);
 	PCALL_RES(lua_pcall(L, 3, 1, error_handler));
 	lua_remove(L, error_handler);
-	return (bool) lua_isboolean(L, -1) && (bool) lua_toboolean(L, -1);
+	return readParam<bool>(L, -1, false);
 }
 
 void ScriptApiNode::node_after_destruct(v3s16 p, MapNode node)
@@ -231,7 +231,7 @@ bool ScriptApiNode::node_on_timer(v3s16 p, MapNode node, f32 dtime)
 	lua_pushnumber(L,dtime);
 	PCALL_RES(lua_pcall(L, 2, 1, error_handler));
 	lua_remove(L, error_handler);
-	return (bool) lua_isboolean(L, -1) && (bool) lua_toboolean(L, -1);
+	return readParam<bool>(L, -1, false);
 }
 
 void ScriptApiNode::node_on_receive_fields(v3s16 p,
diff --git a/src/script/cpp_api/s_player.cpp b/src/script/cpp_api/s_player.cpp
index 0097177c4..100434fc3 100644
--- a/src/script/cpp_api/s_player.cpp
+++ b/src/script/cpp_api/s_player.cpp
@@ -74,7 +74,7 @@ bool ScriptApiPlayer::on_punchplayer(ServerActiveObject *player,
 	push_v3f(L, dir);
 	lua_pushnumber(L, damage);
 	runCallbacks(6, RUN_CALLBACKS_MODE_OR);
-	return lua_toboolean(L, -1);
+	return readParam<bool>(L, -1);
 }
 
 s16 ScriptApiPlayer::on_player_hpchange(ServerActiveObject *player,
@@ -111,8 +111,7 @@ bool ScriptApiPlayer::on_respawnplayer(ServerActiveObject *player)
 	// Call callbacks
 	objectrefGetOrCreate(L, player);
 	runCallbacks(1, RUN_CALLBACKS_MODE_OR);
-	bool positioning_handled_by_some = lua_toboolean(L, -1);
-	return positioning_handled_by_some;
+	return readParam<bool>(L, -1);
 }
 
 bool ScriptApiPlayer::on_prejoinplayer(
@@ -129,7 +128,7 @@ bool ScriptApiPlayer::on_prejoinplayer(
 	lua_pushstring(L, ip.c_str());
 	runCallbacks(2, RUN_CALLBACKS_MODE_OR);
 	if (lua_isstring(L, -1)) {
-		reason->assign(lua_tostring(L, -1));
+		reason->assign(readParam<std::string>(L, -1));
 		return true;
 	}
 	return false;
diff --git a/src/script/cpp_api/s_security.cpp b/src/script/cpp_api/s_security.cpp
index 6c50218d3..e87f16ddd 100644
--- a/src/script/cpp_api/s_security.cpp
+++ b/src/script/cpp_api/s_security.cpp
@@ -524,7 +524,7 @@ bool ScriptApiSecurity::checkPath(lua_State *L, const char *path,
 	// Get mod name
 	lua_rawgeti(L, LUA_REGISTRYINDEX, CUSTOM_RIDX_CURRENT_MOD_NAME);
 	if (lua_isstring(L, -1)) {
-		std::string mod_name = lua_tostring(L, -1);
+		std::string mod_name = readParam<std::string>(L, -1);
 
 		// Builtin can access anything
 		if (mod_name == BUILTIN_MOD_NAME) {
@@ -649,7 +649,7 @@ int ScriptApiSecurity::sl_g_loadfile(lua_State *L)
 	lua_pop(L, 1);
 
 	if (script->getType() == ScriptingType::Client) {
-		std:: string display_path = lua_tostring(L, 1);
+		std::string display_path = readParam<std::string>(L, 1);
 		const std::string *path = script->getClient()->getModFile(display_path);
 		if (!path) {
 			std::string error_msg = "Coudln't find script called:" + display_path;
diff --git a/src/script/cpp_api/s_server.cpp b/src/script/cpp_api/s_server.cpp
index b0459fbfa..3b461a2a3 100644
--- a/src/script/cpp_api/s_server.cpp
+++ b/src/script/cpp_api/s_server.cpp
@@ -88,7 +88,7 @@ void ScriptApiServer::readPrivileges(int index, std::set<std::string> &result)
 	while (lua_next(L, index) != 0) {
 		// key at index -2 and value at index -1
 		std::string key = luaL_checkstring(L, -2);
-		bool value = lua_toboolean(L, -1);
+		bool value = readParam<bool>(L, -1);
 		if (value)
 			result.insert(key);
 		// removes value, keeps key for next iteration
@@ -143,8 +143,7 @@ bool ScriptApiServer::on_chat_message(const std::string &name,
 	lua_pushstring(L, name.c_str());
 	lua_pushstring(L, message.c_str());
 	runCallbacks(2, RUN_CALLBACKS_MODE_OR_SC);
-	bool ate = lua_toboolean(L, -1);
-	return ate;
+	return readParam<bool>(L, -1);
 }
 
 void ScriptApiServer::on_mods_loaded()