Lua API: Add wesnoth.compile_formula which returns a callable userdata

src/scripting/game_lua_kernel.cpp

@@ -4257,6 +4257,7 @@ game_lua_kernel::game_lua_kernel(CVideo * video, game_state & gs, play_controlle
 		{ "add_known_unit",           &intf_add_known_unit           },
 		{ "add_modification",         &intf_add_modification         },
 		{ "advance_unit",             &intf_advance_unit             },
+		{ "compile_formula",          &lua_formula_bridge::intf_compile_formula},
 		{ "copy_unit",                &intf_copy_unit                },
 		{ "create_unit",              &intf_create_unit              },
 		{ "debug",                    &intf_debug                    },
@@ -4455,6 +4456,9 @@ game_lua_kernel::game_lua_kernel(CVideo * video, game_state & gs, play_controlle
 	lua_pushstring(L, "unit variables");
 	lua_setfield(L, -2, "__metatable");
 	lua_rawset(L, LUA_REGISTRYINDEX);
+
+	// Create formula bridge metatables
+	cmd_log_ << lua_formula_bridge::register_metatables(L);
 
 	// Create the vconfig metatable.
 	cmd_log_ << lua_common::register_vconfig_metatable(L);

src/scripting/lua_formula_bridge.cpp

@@ -201,11 +201,14 @@ variant luaW_tofaivariant(lua_State* L, int i) {
  */
 int lua_formula_bridge::intf_eval_formula(lua_State *L)
 {
-	using namespace game_logic;
-	if(!lua_isstring(L, 1)) {
-		luaL_typerror(L, 1, "string");
+	bool need_delete = false;
+	fwrapper* form;
+	if(luaW_hasmetatable(L, 1, formulaKey)) {
+		form = static_cast<fwrapper*>(lua_touserdata(L, 1));
+	} else {
+		need_delete = true;
+		form = new fwrapper(luaL_checkstring(L, 1));
 	}
-	const formula form(lua_tostring(L, 1));
 	boost::shared_ptr<formula_callable> context, fallback;
 	if(unit* u = luaW_tounit(L, 2)) {
 		context.reset(new unit_callable(*u));
@@ -214,7 +217,75 @@ int lua_formula_bridge::intf_eval_formula(lua_State *L)
 	} else {
 		context.reset(new map_formula_callable);
 	}
-	variant result = form.evaluate(*context);
+	variant result = form->evaluate(*context);
 	luaW_pushfaivariant(L, result);
+	if(need_delete) {
+		delete form;
+	}
 	return 1;
 }
+
+int lua_formula_bridge::intf_compile_formula(lua_State* L)
+{
+	if(!lua_isstring(L, 1)) {
+		luaL_typerror(L, 1, "string");
+	}
+	new(lua_newuserdata(L, sizeof(fwrapper))) fwrapper(lua_tostring(L, 1));
+	lua_pushlightuserdata(L, formulaKey);
+	lua_rawget(L, LUA_REGISTRYINDEX);
+	lua_setmetatable(L, -2);
+	return 1;
+}
+
+lua_formula_bridge::fwrapper::fwrapper(const std::string& code, game_logic::function_symbol_table* functions)
+	: formula_ptr(new formula(code, functions))
+{
+}
+
+std::string lua_formula_bridge::fwrapper::str() const
+{
+	if(formula_ptr) {
+		return formula_ptr->str();
+	}
+	return "";
+}
+
+variant lua_formula_bridge::fwrapper::evaluate(const formula_callable& variables, formula_debugger* fdb) const
+{
+	if(formula_ptr) {
+		return formula_ptr->evaluate(variables, fdb);
+	}
+	return variant();
+}
+
+static int impl_formula_collect(lua_State* L)
+{
+	lua_formula_bridge::fwrapper* form = static_cast<lua_formula_bridge::fwrapper*>(lua_touserdata(L, 1));
+	form->~fwrapper();
+	return 0;
+}
+
+static int impl_formula_tostring(lua_State* L)
+{
+	lua_formula_bridge::fwrapper* form = static_cast<lua_formula_bridge::fwrapper*>(lua_touserdata(L, 1));
+	const std::string str = form->str();
+	lua_pushlstring(L, str.c_str(), str.size());
+	return 1;
+}
+
+std::string lua_formula_bridge::register_metatables(lua_State* L)
+{
+	lua_pushlightuserdata(L, formulaKey);
+	lua_createtable(L, 0, 4);
+	lua_pushcfunction(L, impl_formula_collect);
+	lua_setfield(L, -2, "__gc");
+	lua_pushcfunction(L, impl_formula_tostring);
+	lua_setfield(L, -2, "__tostring");
+	lua_pushcfunction(L, intf_eval_formula);
+	lua_setfield(L, -2, "__call");
+	lua_pushstring(L, "formula");
+	lua_setfield(L, -2, "__metatable");
+	lua_rawset(L, LUA_REGISTRYINDEX);
+
+	return "Adding formula metatable...";
+}

src/scripting/lua_formula_bridge.hpp

@@ -14,11 +14,32 @@
 #ifndef LUA_FORMULA_BRIDGE_HPP_INCLUDED
 #define LUA_FORMULA_BRIDGE_HPP_INCLUDED
 
+#include <string>
+#include <boost/shared_ptr.hpp>
+
 struct lua_State;
 
+class variant;
+namespace game_logic {
+	class formula;
+	class function_symbol_table;
+	class formula_debugger;
+	class formula_callable;
+}
+
 namespace lua_formula_bridge {
 
 	int intf_eval_formula(lua_State*);
+	int intf_compile_formula(lua_State*);
+	std::string register_metatables(lua_State*);
+
+	class fwrapper {
+		boost::shared_ptr<game_logic::formula> formula_ptr;
+	public:
+		fwrapper(const std::string& code, game_logic::function_symbol_table* functions = NULL);
+		std::string str() const;
+		variant evaluate(const game_logic::formula_callable& variables, game_logic::formula_debugger* fdb = NULL) const;
+	};
 
 } // end namespace lua_formula_bridge
 

src/scripting/lua_types.cpp

@@ -21,6 +21,7 @@ static char const v_unitvarKey = 0;
 static char const v_ustatusKey = 0;
 static char const v_uattacksKey = 0;
 static char const v_uattackKey = 0;
+static char const v_formulaKey = 0;
 
 
 luatypekey const executeKey = static_cast<void *>(const_cast<char *>(&v_executeKey));
@@ -29,3 +30,4 @@ luatypekey const unitvarKey = static_cast<void *>(const_cast<char *>(&v_unitvarK
 luatypekey const ustatusKey = static_cast<void *>(const_cast<char *>(&v_ustatusKey));
 luatypekey const uattacksKey = static_cast<void *>(const_cast<char *>(&v_uattacksKey));
 luatypekey const uattackKey = static_cast<void *>(const_cast<char *>(&v_uattackKey));
+luatypekey const formulaKey = static_cast<void *>(const_cast<char *>(&v_formulaKey));

src/scripting/lua_types.hpp

@@ -25,5 +25,6 @@ extern luatypekey const unitvarKey;
 extern luatypekey const ustatusKey;
 extern luatypekey const uattacksKey;
 extern luatypekey const uattackKey;
+extern luatypekey const formulaKey;
 
 #endif