From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Serge Petrenko Subject: [PATCH v3 4/5] lua/utils: add a function to register FFI metatypes. Date: Tue, 2 Jul 2019 20:27:51 +0300 Message-Id: <5530a0090722e5a1e44e0f680ed643ee6efee2b2.1562087728.git.sergepetrenko@tarantool.org> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit To: vdavydov.dev@gmail.com Cc: tarantool-patches@freelists.org, Serge Petrenko List-ID: A ffi metatype has a CTypeID, which can be used to push cdata of the type on the lua stack, and has an associated metatable, automatically applied to every created member of the type. This allows the behavior similar to pushing userdata and assigning a metatable to it. Needed for #692 --- src/lua/utils.c | 28 ++++++++++++++++++++++++++++ src/lua/utils.h | 13 +++++++++++++ 2 files changed, 41 insertions(+) diff --git a/src/lua/utils.c b/src/lua/utils.c index 01a0cd894..0a4bcf517 100644 --- a/src/lua/utils.c +++ b/src/lua/utils.c @@ -141,6 +141,34 @@ luaL_ctypeid(struct lua_State *L, const char *ctypename) return ctypeid; } +uint32_t +luaL_metatype(struct lua_State *L, const char *ctypename, + const struct luaL_Reg *methods) +{ + /* Create a metatable for our ffi metatype. */ + luaL_register_type(L, ctypename, methods); + int idx = lua_gettop(L); + /* + * Get ffi.metatype function. It is like typeof with + * an additional effect of registering a metatable for + * all the cdata objects of the type. + */ + luaL_loadstring(L, "return require('ffi').metatype"); + lua_call(L, 0, 1); + assert(lua_gettop(L) == idx + 1 && lua_isfunction(L, idx + 1)); + lua_pushstring(L, ctypename); + /* Push the freshly created metatable as the second parameter. */ + luaL_getmetatable(L, ctypename); + assert(lua_gettop(L) == idx + 3 && lua_istable(L, idx + 3)); + lua_call(L, 2, 1); + uint32_t ctypetypeid; + CTypeID ctypeid = *(CTypeID *)luaL_checkcdata(L, idx + 1, &ctypetypeid); + assert(ctypetypeid == CTID_CTYPEID); + + lua_settop(L, idx); + return ctypeid; +} + int luaL_cdef(struct lua_State *L, const char *what) { diff --git a/src/lua/utils.h b/src/lua/utils.h index 943840ec0..7e7cdc0c6 100644 --- a/src/lua/utils.h +++ b/src/lua/utils.h @@ -129,6 +129,19 @@ luaL_cdef(struct lua_State *L, const char *ctypename); /** \endcond public */ +/** + * @brief Return CTypeID (FFI) of given CDATA type, + * register a metatable with \a methods to be + * associated with every value of the given + * type on its creation iva FFI. + * @sa luaL_register_type + * @sa luaL_ctypeid + * @return CTypeID + */ +uint32_t +luaL_metatype(struct lua_State *L, const char *ctypename, + const struct luaL_Reg *methods); + static inline lua_Integer luaL_arrlen(struct lua_State *L, int idx) { -- 2.20.1 (Apple Git-117)