variables in lua mapgen, fixes #3657

In campaigns The lua mapgenerator code has now access to the
variables from the last scenario via wesnoth.get_variable.

src/generators/lua_map_generator.cpp

@@ -20,14 +20,15 @@
 
 #include <string>
 
-lua_map_generator::lua_map_generator(const config & cfg)
+lua_map_generator::lua_map_generator(const config & cfg, const config* vars)
 	: id_(cfg["id"])
 	, config_name_(cfg["config_name"])
 	, user_config_(cfg["user_config"])
 	, create_map_(cfg["create_map"])
 	, create_scenario_(cfg["create_scenario"])
-	, lk_()
+	, lk_(vars)
 	, generator_data_(cfg)
+	, vars_(vars)
 {
 	lk_.load_core();
 	const char* required[] {"id", "config_name", "create_map"};

src/generators/lua_map_generator.hpp

@@ -23,7 +23,7 @@
 
 class lua_map_generator : public map_generator {
 public:
-	lua_map_generator(const config & cfg);
+	lua_map_generator(const config & cfg, const config* vars);
 
 	bool allow_user_config() const override { return !user_config_.empty(); }
 
@@ -47,4 +47,5 @@ private:
 	mapgen_lua_kernel lk_;
 
 	config generator_data_;
+	const config* vars_;
 };

src/generators/map_create.cpp

@@ -25,7 +25,7 @@
 static lg::log_domain log_config("config");
 #define ERR_CF LOG_STREAM(err, log_config)
 
-map_generator* create_map_generator(const std::string& name, const config &cfg)
+map_generator* create_map_generator(const std::string& name, const config &cfg, const config* vars)
 {
 	if(name == "default" || name.empty()) {
 		return new default_map_generator(cfg);
@@ -33,7 +33,7 @@ map_generator* create_map_generator(const std::string& name, const config &cfg)
 		ERR_CF << "map/scenario_generation=cave is deprecatd and will be removed soon, use map/scenario_generation=lua with lua/cave_map_generator.lua instead.\n";
 		return new cave_map_generator(cfg);
 	} else if(name == "lua") {
-		return new lua_map_generator(cfg);
+		return new lua_map_generator(cfg, vars);
 	} else {
 		return nullptr;
 	}
@@ -41,9 +41,9 @@ map_generator* create_map_generator(const std::string& name, const config &cfg)
 
 //function to generate a random map, from a string which describes
 //the generator to use
-std::string random_generate_map(const std::string& name, const config &cfg)
+std::string random_generate_map(const std::string& name, const config &cfg, const config* vars)
 {
-	std::unique_ptr<map_generator> generator(create_map_generator(name,cfg));
+	std::unique_ptr<map_generator> generator(create_map_generator(name, cfg, vars));
 	if(generator == nullptr) {
 		std::stringstream ss;
 		ss << "could not find map generator '" << name << "'";
@@ -53,9 +53,9 @@ std::string random_generate_map(const std::string& name, const config &cfg)
 	return generator->create_map();
 }
 
-config random_generate_scenario(const std::string& name, const config &cfg)
+config random_generate_scenario(const std::string& name, const config &cfg, const config* vars)
 {
-	std::unique_ptr<map_generator> generator(create_map_generator(name,cfg));
+	std::unique_ptr<map_generator> generator(create_map_generator(name, cfg, vars));
 	if(generator == nullptr) {
 		std::stringstream ss;
 		ss << "could not find map generator '" << name << "'";

src/generators/map_create.hpp

@@ -19,7 +19,7 @@ class map_generator;
 
 #include <string>
 
-std::string random_generate_map(const std::string& parms, const config &cfg);
-config random_generate_scenario(const std::string& parms, const config &cfg);
+std::string random_generate_map(const std::string& parms, const config &cfg, const config* vars = nullptr);
+config random_generate_scenario(const std::string& parms, const config &cfg, const config* vars = nullptr);
 
-map_generator* create_map_generator(const std::string& name, const config &cfg);
+map_generator* create_map_generator(const std::string& name, const config &cfg, const config* vars = nullptr);

src/saved_game.cpp

@@ -427,7 +427,7 @@ void saved_game::expand_random_scenario()
 			const cursor::setter cursor_setter(cursor::WAIT);
 
 			config scenario_new =
-				random_generate_scenario(starting_point_["scenario_generation"], starting_point_.child("generator"));
+				random_generate_scenario(starting_point_["scenario_generation"], starting_point_.child("generator"), &carryover_.child_or_empty("variables"));
 
 			post_scenario_generation(starting_point_, scenario_new);
 			starting_point_ = std::move(scenario_new);
@@ -448,7 +448,7 @@ void saved_game::expand_random_scenario()
 			const cursor::setter cursor_setter(cursor::WAIT);
 
 			starting_point_["map_data"] =
-				random_generate_map(starting_point_["map_generation"], starting_point_.child("generator"));
+				random_generate_map(starting_point_["map_generation"], starting_point_.child("generator"), &carryover_.child_or_empty("variables"));
 		}
 	}
 }

src/scripting/mapgen_lua_kernel.cpp

@@ -40,6 +40,13 @@ static lg::log_domain log_mapgen("mapgen");
 struct lua_State;
 
 
+// Template which allows to push member functions to the lua kernel into lua as C functions, using a shim
+typedef int (mapgen_lua_kernel::*member_callback)(lua_State *);
+
+template <member_callback method>
+int dispatch(lua_State *L) {
+	return ((lua_kernel_base::get_lua_kernel<mapgen_lua_kernel>(L)).*method)(L);
+}
 
 /**
  * Returns a random numer, same interface as math.random.
@@ -196,10 +203,11 @@ static int intf_find_path(lua_State *L)
 }
 
 
-mapgen_lua_kernel::mapgen_lua_kernel()
+mapgen_lua_kernel::mapgen_lua_kernel(const config* vars)
 	: lua_kernel_base()
 	, random_seed_()
 	, default_rng_()
+	, vars_(vars)
 {
 	lua_State *L = mState;
 
@@ -218,6 +226,7 @@ mapgen_lua_kernel::mapgen_lua_kernel()
 		{ "create_map",          &intf_terainmap_create    },
 		{ "default_generate_height_map", &intf_default_generate_height_map },
 		{ "generate_default_map",        &intf_default_generate            },
+		{ "get_variable", &dispatch<&mapgen_lua_kernel::intf_get_variable> },
 		{ nullptr, nullptr }
 	};
 
@@ -244,6 +253,16 @@ void mapgen_lua_kernel::user_config(const char * prog, const config & generator)
 	run_generator(prog, generator);
 }
 
+int mapgen_lua_kernel::intf_get_variable(lua_State *L)
+{
+	if(!vars_) {
+		return 0;
+	}
+
+	char const *m = luaL_checkstring(L, 1);
+	variable_access_const v(m, *vars_);
+	return luaW_pushvariable(L, v) ? 1 : 0;
+}
 std::string mapgen_lua_kernel::create_map(const char * prog, const config & generator, boost::optional<uint32_t> seed) // throws game::lua_error
 {
 	random_seed_ = seed;

src/scripting/mapgen_lua_kernel.hpp

@@ -25,7 +25,7 @@ class config;
 
 class mapgen_lua_kernel : public lua_kernel_base {
 public:
-	mapgen_lua_kernel();
+	mapgen_lua_kernel(const config* vars);
 
 	virtual std::string my_name() { return "Mapgen Lua Kernel"; }
 
@@ -37,6 +37,8 @@ public:
 	std::mt19937& get_default_rng();
 private:
 	void run_generator(const char * prog, const config & generator);
+	int intf_get_variable(lua_State *L);
 	boost::optional<uint32_t> random_seed_;
 	boost::optional<std::mt19937> default_rng_;
+	const config* vars_;
 };