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Diffstat (limited to 'indra/llcommon/lua_function.h')
| -rw-r--r-- | indra/llcommon/lua_function.h | 256 |
1 files changed, 256 insertions, 0 deletions
diff --git a/indra/llcommon/lua_function.h b/indra/llcommon/lua_function.h new file mode 100644 index 0000000000..07848e38af --- /dev/null +++ b/indra/llcommon/lua_function.h @@ -0,0 +1,256 @@ +/** + * @file lua_function.h + * @author Nat Goodspeed + * @date 2024-02-05 + * @brief Definitions useful for coding a new Luau entry point into C++ + * + * $LicenseInfo:firstyear=2024&license=viewerlgpl$ + * Copyright (c) 2024, Linden Research, Inc. + * $/LicenseInfo$ + */ + +#if ! defined(LL_LUA_FUNCTION_H) +#define LL_LUA_FUNCTION_H + +#include "luau/luacode.h" +#include "luau/lua.h" +#include "luau/luaconf.h" +#include "luau/lualib.h" +#include "stringize.h" +#include <exception> // std::uncaught_exceptions() +#include <memory> // std::shared_ptr +#include <utility> // std::pair + +class LuaListener; + +#define lua_register(L, n, f) (lua_pushcfunction(L, (f), n), lua_setglobal(L, (n))) +#define lua_rawlen lua_objlen + +namespace lluau +{ + // luau defines luaL_error() as void, but we want to use the Lua idiom of + // 'return error(...)'. Wrap luaL_error() in an int function. +#if __clang__ +#pragma clang diagnostic push +#pragma clang diagnostic ignored "-Wformat-security" +#endif // __clang__ + template<typename... Args> + int error(lua_State* L, const char* format, Args&&... args) + { + luaL_error(L, format, std::forward<Args>(args)...); +#ifndef LL_MSVC + return 0; +#endif + } +#if __clang__ +#pragma clang diagnostic pop +#endif // __clang__ + + // luau removed lua_dostring(), but since we perform the equivalent luau + // sequence in multiple places, encapsulate it. desc and text are strings + // rather than string_views because dostring() needs pointers to nul- + // terminated char arrays. + int dostring(lua_State* L, const std::string& desc, const std::string& text); + int loadstring(lua_State* L, const std::string& desc, const std::string& text); +} // namespace lluau + +std::string lua_tostdstring(lua_State* L, int index); +void lua_pushstdstring(lua_State* L, const std::string& str); +LLSD lua_tollsd(lua_State* L, int index); +void lua_pushllsd(lua_State* L, const LLSD& data); + +/** + * RAII class to manage the lifespan of a lua_State + */ +class LuaState +{ +public: + typedef std::function<void(std::string msg)> script_finished_fn; + + LuaState(script_finished_fn cb={}); + + LuaState(const LuaState&) = delete; + LuaState& operator=(const LuaState&) = delete; + + ~LuaState(); + + void initLuaState(); + + bool checkLua(const std::string& desc, int r); + + // expr() is for when we want to capture any results left on the stack + // by a Lua expression, possibly including multiple return values. + // int < 0 means error, and LLSD::asString() is the error message. + // int == 0 with LLSD::isUndefined() means the Lua expression returned no + // results. + // int == 1 means the Lua expression returned one result. + // int > 1 with LLSD::isArray() means the Lua expression returned + // multiple results, represented as the entries of the array. + std::pair<int, LLSD> expr(const std::string& desc, const std::string& text); + + operator lua_State*() const { return mState; } + + // Return LuaListener for this LuaState if we already have one, else empty + // shared_ptr. + std::shared_ptr<LuaListener> getListener() { return getListener(mState); } + // Find or create LuaListener for this LuaState, returning its ptr_t. + std::shared_ptr<LuaListener> obtainListener() { return obtainListener(mState); } + // Return LuaListener for passed lua_State if we already have one, else + // empty shared_ptr. + static std::shared_ptr<LuaListener> getListener(lua_State* L); + // Find or create LuaListener for passed lua_State, returning its ptr_t. + static std::shared_ptr<LuaListener> obtainListener(lua_State* L); + +private: + script_finished_fn mCallback; + lua_State* mState; + std::string mError; +}; + +/** + * LuaPopper is an RAII struct whose role is to pop some number of entries + * from the Lua stack if the calling function exits early. + */ +struct LuaPopper +{ + LuaPopper(lua_State* L, int count): + mState(L), + mCount(count) + {} + + LuaPopper(const LuaPopper&) = delete; + LuaPopper& operator=(const LuaPopper&) = delete; + + ~LuaPopper(); + + void disarm() { set(0); } + void set(int count) { mCount = count; } + + lua_State* mState; + int mCount; +}; + +/** + * LuaFunction is a base class containing a static registry of its static + * subclass call() methods. call() is NOT virtual: instead, each subclass + * constructor passes a pointer to its distinct call() method to the base- + * class constructor, along with a name by which to register that method. + * + * The init() method walks the registry and registers each such name with the + * passed lua_State. + */ +class LuaFunction +{ +public: + LuaFunction(const std::string_view& name, lua_CFunction function, + const std::string_view& helptext); + + static void init(lua_State* L); + + static lua_CFunction get(const std::string& key); + +protected: + using Registry = std::map<std::string, std::pair<lua_CFunction, std::string>>; + using Lookup = std::map<lua_CFunction, std::string>; + static std::pair<const Registry&, const Lookup&> getRState() { return getState(); } + +private: + static std::pair<Registry&, Lookup&> getState(); +}; + +/** + * lua_function(name, helptext) is a macro to facilitate defining C++ functions + * available to Lua. It defines a subclass of LuaFunction and declares a + * static instance of that subclass, thereby forcing the compiler to call its + * constructor at module initialization time. The constructor passes the + * stringized instance name to its LuaFunction base-class constructor, along + * with a pointer to the static subclass call() method. It then emits the + * call() method definition header, to be followed by a method body enclosed + * in curly braces as usual. + */ +#define lua_function(name, helptext) \ +static struct name##_luasub : public LuaFunction \ +{ \ + name##_luasub(): LuaFunction(#name, &call, helptext) {} \ + static int call(lua_State* L); \ +} name##_lua; \ +int name##_luasub::call(lua_State* L) +// { +// ... supply method body here, referencing 'L' ... +// } + +// Usage: std::cout << lua_what(L, stackindex) << ...; +// Reports on the Lua value found at the passed stackindex. +// If cast to std::string, returns the corresponding string value. +class lua_what +{ +public: + lua_what(lua_State* state, int idx): + L(state), + index(idx) + {} + + friend std::ostream& operator<<(std::ostream& out, const lua_what& self); + + operator std::string() const { return stringize(*this); } + +private: + lua_State* L; + int index; +}; + +// Usage: std::cout << lua_stack(L) << ...; +// Reports on the contents of the Lua stack. +// If cast to std::string, returns the corresponding string value. +class lua_stack +{ +public: + lua_stack(lua_State* state): + L(state) + {} + + friend std::ostream& operator<<(std::ostream& out, const lua_stack& self); + + operator std::string() const { return stringize(*this); } + +private: + lua_State* L; +}; + +// adapted from indra/test/debug.h +// can't generalize Debug::operator() target because it's a variadic template +class LuaLog +{ +public: + template <typename... ARGS> + LuaLog(lua_State* L, ARGS&&... args): + L(L), + mBlock(stringize(std::forward<ARGS>(args)...)) + { + (*this)("entry ", lua_stack(L)); + } + + // non-copyable + LuaLog(const LuaLog&) = delete; + LuaLog& operator=(const LuaLog&) = delete; + + ~LuaLog() + { + auto exceptional{ std::uncaught_exceptions()? "exceptional " : "" }; + (*this)(exceptional, "exit ", lua_stack(L)); + } + + template <typename... ARGS> + void operator()(ARGS&&... args) + { + LL_INFOS("Lua") << mBlock << ' '; + stream_to(LL_CONT, std::forward<ARGS>(args)...); + LL_ENDL; + } + +private: + lua_State* L; + const std::string mBlock; +}; + +#endif /* ! defined(LL_LUA_FUNCTION_H) */ |