Allow accessing variables through the new APIs in the mapgen kernel

This also reverses the deprecation of wml.tovconfig and friends in the mapgen kernel.

data/campaigns/World_Conquest/lua/map/main.lua

@@ -37,9 +37,9 @@ function wc_ii_generate_scenario(nplayers, gen_args)
 	nplayers = settings.nplayers or nplayers
 	local id_suffix = gen_args.id_suffix or ""
 	local scenario_extra = wml.get_child(gen_args, "scenario")
-	local scenario_num = settings.scenario_num or wesnoth.get_variable("wc2_scenario") or 1
+	local scenario_num = settings.scenario_num or wml.variables.wc2_scenario or 1
 	--todo: does this work properly in the first scenario?
-	local enemy_stength = wesnoth.get_variable("wc2_difficulty.enemy_power") or 6
+	local enemy_stength = wml.variables["wc2_difficulty.enemy_power"] or 6
 	local scenario_data = wesnoth.dofile(string.format("./scenarios/WC_II_%dp_scenario%d.lua", nplayers, scenario_num))
 
 	local prestart_event = { name = "prestart" }

data/campaigns/World_Conquest/lua/map/scenario_utils/bonus_points.lua

@@ -65,7 +65,7 @@ function random_placement(locs, num_items, min_distance, command)
 end
 
 function get_f_wct_bonus_location_filter(map)
-	local scenario_num = wesnoth.get_variable("wc2_scenario") or 1
+	local scenario_num = wml.variables.wc2_scenario or 1
 	return f.all(
 		f.terrain("G*,Hh,Uu,Uh,Dd,Ds,R*,Mm,Md,Ss,Hd,Hhd,Ww,Wwt,Wwg,Ds^Esd,Ur"),
 		--no adjacent to village, deep water, chasm or walls
@@ -399,7 +399,7 @@ end
 
 function world_conquest_tek_bonus_points(theme)
 	local res = {}
-	local scenario_num = wesnoth.get_variable("wc2_scenario") or 1
+	local scenario_num = wml.variables.wc2_scenario or 1
 	oceanic = get_oceanic()
 	f_wct_bonus_location_filter = wesnoth.map.filter(get_f_wct_bonus_location_filter(map), { oceanic = oceanic })
 	local possible_locs = map:find(f_wct_bonus_location_filter)

data/lua/core/wml.lua

@@ -192,7 +192,9 @@ if wesnoth.kernel_type() == "Game Lua Kernel" then
 	function wml.fire(name, cfg)
 		wesnoth.wml_actions[name](wml.tovconfig(cfg or {}))
 	end
+end
 
+if wesnoth.kernel_type() ~= "Application Lua Kernel" then
 	--[========[Basic variable access]========]
 
 	-- Get all variables via wml.all_variables (read-only)
@@ -215,7 +217,9 @@ if wesnoth.kernel_type() == "Game Lua Kernel" then
 	})
 
 	local get_variable_local = wml.get_variable
-	local set_variable_local = wml.set_variable
+	local set_variable_local = wml.set_variable or function()
+		error("Variables are read-only during map generation", 3)
+	end
 
 	-- Get and set variables via wml.variables[variable_path]
 	wml.variables = setmetatable({}, {
@@ -438,10 +442,13 @@ wesnoth.tovconfig = wesnoth.deprecate_api('wesnoth.tovconfig', 'wml.tovconfig',
 wesnoth.debug = wesnoth.deprecate_api('wesnoth.debug', 'wml.tostring', 1, nil, wml.tostring)
 wesnoth.wml_matches_filter = wesnoth.deprecate_api('wesnoth.wml_matches_filter', 'wml.matches_filter', 1, nil, wml.matches_filter)
 
-if wesnoth.kernel_type() == "Game Lua Kernel" then
+if wesnoth.kernel_type() ~= "Application Lua Kernel" then
 	wesnoth.get_variable = wesnoth.deprecate_api('wesnoth.get_variable', 'wml.variables', 1, nil, wml.get_variable)
-	wesnoth.set_variable = wesnoth.deprecate_api('wesnoth.set_variable', 'wml.variables', 1, nil, wml.set_variable)
 	wesnoth.get_all_vars = wesnoth.deprecate_api('wesnoth.get_all_vars', 'wml.all_variables', 1, nil, wml.get_all_vars)
+end
+
+if wesnoth.kernel_type() == "Game Lua Kernel" then
+	wesnoth.set_variable = wesnoth.deprecate_api('wesnoth.set_variable', 'wml.variables', 1, nil, wml.set_variable)
 	wesnoth.fire = wesnoth.deprecate_api('wesnoth.fire', 'wml.fire', 1, nil, wml.fire)
 	wesnoth.eval_conditional = wesnoth.deprecate_api('wesnoth.eval_conditional', 'wml.eval_conditional', 1, nil, wml.eval_conditional)
 end

src/scripting/mapgen_lua_kernel.cpp

@@ -222,7 +222,6 @@ mapgen_lua_kernel::mapgen_lua_kernel(const config* vars)
 	static luaL_Reg const callbacks[] {
 		{ "find_path",           &intf_find_path           },
 		{ "random",              &intf_random              },
-		{ "get_variable", &dispatch<&mapgen_lua_kernel::intf_get_variable> },
 		{ nullptr, nullptr }
 	};
 
@@ -249,6 +248,18 @@ mapgen_lua_kernel::mapgen_lua_kernel(const config* vars)
 	luaL_setfuncs(L, map_callbacks, 0);
 	lua_pop(L, 1);
 	assert(lua_gettop(L) == 0);
+	
+	// Add functions to the WML module
+	lua_getglobal(L, "wml");
+	static luaL_Reg const wml_callbacks[] {
+		{"tovconfig", &lua_common::intf_tovconfig},
+		// These aren't actually part of the API - they're used internally by the variable metatable.
+		{ "get_variable", &dispatch<&mapgen_lua_kernel::intf_get_variable>},
+		{ "get_all_vars", &dispatch<&mapgen_lua_kernel::intf_get_all_vars>},
+		{ nullptr, nullptr }
+	};
+	luaL_setfuncs(L, wml_callbacks, 0);
+	lua_pop(L, 1);
 
 	cmd_log_ << lua_terrainmap::register_metatables(L);
 	cmd_log_ << lua_terrainfilter::register_metatables(L);
@@ -268,12 +279,17 @@ void mapgen_lua_kernel::user_config(const char * prog, const config & generator)
 
 int mapgen_lua_kernel::intf_get_variable(lua_State *L)
 {
-	static const config empty_cfg;
 
 	char const *m = luaL_checkstring(L, 1);
-	variable_access_const v(m, vars_ ? *vars_ : empty_cfg);
+	variable_access_const v(m, vars_ ? *vars_ : config());
 	return luaW_pushvariable(L, v) ? 1 : 0;
 }
+
+int mapgen_lua_kernel::intf_get_all_vars(lua_State *L) {
+	luaW_pushconfig(L, vars_ ? *vars_ : config());
+	return 1;
+}
+
 std::string mapgen_lua_kernel::create_map(const char * prog, const config & generator, std::optional<uint32_t> seed) // throws game::lua_error
 {
 	random_seed_ = seed;

src/scripting/mapgen_lua_kernel.hpp

@@ -39,6 +39,7 @@ public:
 private:
 	void run_generator(const char * prog, const config & generator);
 	int intf_get_variable(lua_State *L);
+	int intf_get_all_vars(lua_State *L);
 	std::optional<uint32_t> random_seed_;
 	std::optional<std::mt19937> default_rng_;
 	const config* vars_;