-LuaJIT adds some extensions to the standard Lua/C API. The LuaJIT include -directory must be in the compiler search path (-Ipath) -to be able to include the required header for C code: -
--#include "luajit.h" --
-Or for C++ code: -
--#include "lua.hpp" -- -
luaJIT_setmode(L, idx, mode) -— Control VM
--This is a C API extension to allow control of the VM from C code. The -full prototype of LuaJIT_setmode is: -
--LUA_API int luaJIT_setmode(lua_State *L, int idx, int mode); --
-The returned status is either success (1) or failure (0). -The second argument is either 0 or a stack index (similar to the -other Lua/C API functions). -
--The third argument specifies the mode, which is 'or'ed with a flag. -The flag can be LUAJIT_MODE_OFF to turn a feature on, -LUAJIT_MODE_ON to turn a feature off, or -LUAJIT_MODE_FLUSH to flush cached code. -
--The following modes are defined: -
- -luaJIT_setmode(L, 0, LUAJIT_MODE_ENGINE|flag)
--Turn the whole JIT compiler on or off or flush the whole cache of compiled code. -
- -luaJIT_setmode(L, idx, LUAJIT_MODE_FUNC|flag)
-luaJIT_setmode(L, idx, LUAJIT_MODE_ALLFUNC|flag)
-luaJIT_setmode(L, idx, LUAJIT_MODE_ALLSUBFUNC|flag)
--This sets the mode for the function at the stack index idx or -the parent of the calling function (idx = 0). It either -enables JIT compilation for a function, disables it and flushes any -already compiled code or only flushes already compiled code. This -applies recursively to all sub-functions of the function with -LUAJIT_MODE_ALLFUNC or only to the sub-functions with -LUAJIT_MODE_ALLSUBFUNC. -
- -luaJIT_setmode(L, trace,
- LUAJIT_MODE_TRACE|LUAJIT_MODE_FLUSH)
--Flushes the specified root trace and all of its side traces from the cache. -The code for the trace will be retained as long as there are any other -traces which link to it. -
- -luaJIT_setmode(L, idx, LUAJIT_MODE_WRAPCFUNC|flag)
--This mode defines a wrapper function for calls to C functions. If -called with LUAJIT_MODE_ON, the stack index at idx -must be a lightuserdata object holding a pointer to the wrapper -function. From now on all C functions are called through the wrapper -function. If called with LUAJIT_MODE_OFF this mode is turned -off and all C functions are directly called. -
--The wrapper function can be used for debugging purposes or to catch -and convert foreign exceptions. But please read the section on -C++ exception interoperability -first. Recommended usage can be seen in this C++ code excerpt: -
-
-#include <exception>
-#include "lua.hpp"
-
-// Catch C++ exceptions and convert them to Lua error messages.
-// Customize as needed for your own exception classes.
-static int wrap_exceptions(lua_State *L, lua_CFunction f)
-{
- try {
- return f(L); // Call wrapped function and return result.
- } catch (const char *s) { // Catch and convert exceptions.
- lua_pushstring(L, s);
- } catch (std::exception& e) {
- lua_pushstring(L, e.what());
- } catch (...) {
- lua_pushliteral(L, "caught (...)");
- }
- return lua_error(L); // Rethrow as a Lua error.
-}
-
-static int myinit(lua_State *L)
-{
- ...
- // Define wrapper function and enable it.
- lua_pushlightuserdata(L, (void *)wrap_exceptions);
- luaJIT_setmode(L, -1, LUAJIT_MODE_WRAPCFUNC|LUAJIT_MODE_ON);
- lua_pop(L, 1);
- ...
-}
-
--Note that you can only define a single global wrapper function, -so be careful when using this mechanism from multiple C++ modules. -Also note that this mechanism is not without overhead. -
--