[Lua.MapGen] Formula map filters now support taking precompiled formulas instead of a formula string.

src/scripting/lua_formula_bridge.cpp

@@ -217,6 +217,28 @@ variant luaW_tofaivariant(lua_State* L, int i) {
 	return variant();
 }
 
+/**
+ * Get a formula from the stack. If @a allow_str is true, it compiles a formula string if found.
+ * Otherwise, it must be an already-compiled formula.
+ * Raises an error if a formula is not found, or if there's an error in compilation.
+ * Thus, it never returns a null pointer.
+ */
+lua_formula_bridge::fpointer luaW_check_formula(lua_State* L, int idx, bool allow_str) {
+	using namespace lua_formula_bridge;
+	fpointer form;
+	if(void* ud = luaL_testudata(L, idx, formulaKey)) {
+		form.get_deleter() = [](fwrapper*) {};
+		form.reset(static_cast<fwrapper*>(ud));
+		// Setting a no-op deleter guarantees the Lua-held object is not deleted
+	} else if(allow_str) {
+		form.reset(new fwrapper(luaL_checkstring(L, idx)));
+		// Leave deleter at default so it's deleted properly later
+	} else {
+		luaW_type_error(L, idx, "formula");
+	}
+	return form;
+}
+
 /**
  * Evaluates a formula in the formula engine.
  * - Arg 1: Formula string.
@@ -225,14 +247,7 @@ variant luaW_tofaivariant(lua_State* L, int i) {
  */
 int lua_formula_bridge::intf_eval_formula(lua_State *L)
 {
-	bool need_delete = false;
-	fwrapper* form;
-	if(void* ud = luaL_testudata(L, 1, formulaKey)) {
-		form = static_cast<fwrapper*>(ud);
-	} else {
-		need_delete = true;
-		form = new fwrapper(luaL_checkstring(L, 1));
-	}
+	fpointer form = luaW_check_formula(L, 1, true);
 	std::shared_ptr<formula_callable> context, fallback;
 	if(unit* u = luaW_tounit(L, 2)) {
 		context.reset(new unit_callable(*u));
@@ -249,9 +264,6 @@ int lua_formula_bridge::intf_eval_formula(lua_State *L)
 	}
 	variant result = form->evaluate(*context);
 	luaW_pushfaivariant(L, result);
-	if(need_delete) {
-		delete form;
-	}
 	return 1;
 }
 

src/scripting/lua_formula_bridge.hpp

@@ -14,6 +14,7 @@
 
 #pragma once
 
+#include <functional>
 #include <memory>
 #include <string>
 
@@ -41,4 +42,6 @@ namespace lua_formula_bridge {
 		wfl::variant evaluate(const wfl::formula_callable& variables, wfl::formula_debugger* fdb = nullptr) const;
 	};
 
+	using fpointer = std::unique_ptr<fwrapper, std::function<void(fwrapper*)>>;
 } // end namespace lua_formula_bridge
+lua_formula_bridge::fpointer luaW_check_formula(lua_State* L, int idx, bool allow_str);

src/scripting/lua_terrainfilter.cpp

@@ -22,6 +22,7 @@
 #include "map/map.hpp"
 #include "pathutils_impl.hpp"
 #include "scripting/lua_common.hpp"
+#include "scripting/lua_formula_bridge.hpp"
 #include "scripting/push_check.hpp"
 #include "serialization/string_utils.hpp"
 
@@ -548,14 +549,8 @@ public:
 	{
 		LOG_LMG << "creating formula filter";
 		lua_geti(L, -1, 2);
-		std::string code = std::string(luaW_tostring(L, -1));
+		formula_ = luaW_check_formula(L, 1, true);
 		lua_pop(L, 1);
-
-		try {
-			formula_ = std::make_unique<wfl::formula>(code);
-		} catch(const wfl::formula_error& e) {
-			ERR_LMG << "formula error" << e.what();
-		}
 	}
 	bool matches(const gamemap_base&, map_location l) override
 	{
@@ -569,7 +564,7 @@ public:
 			return false;
 		}
 	}
-	std::unique_ptr<wfl::formula> formula_;
+	lua_formula_bridge::fpointer formula_;
 };
 
 // todo: maybe invent a general macro for this string_switch implementation.