LUA_API int lua_getuservalue (lua_State *L, int idx) { StkId o; lua_lock(L); o = index2addr(L, idx); api_check(ttisfulluserdata(o), "full userdata expected"); getuservalue(L, uvalue(o), L->top); api_incr_top(L); lua_unlock(L); return ttnov(L->top - 1); }
/* ** mark an object. Userdata, strings, and closed upvalues are visited ** and turned black here. Other objects are marked gray and added ** to appropriate list to be visited (and turned black) later. (Open ** upvalues are already linked in 'headuv' list.) */ static void reallymarkobject (global_State *g, GCObject *o) { reentry: white2gray(o); switch (o->tt) { case LUA_TSHRSTR: { gray2black(o); g->GCmemtrav += sizelstring(gco2ts(o)->shrlen); break; } case LUA_TLNGSTR: { gray2black(o); g->GCmemtrav += sizelstring(gco2ts(o)->u.lnglen); break; } case LUA_TUSERDATA: { TValue uvalue; markobjectN(g, gco2u(o)->metatable); /* mark its metatable */ gray2black(o); g->GCmemtrav += sizeudata(gco2u(o)); getuservalue(g->mainthread, gco2u(o), &uvalue); if (valiswhite(&uvalue)) { /* markvalue(g, &uvalue); */ o = gcvalue(&uvalue); goto reentry; } break; } case LUA_TLCL: { linkgclist(gco2lcl(o), g->gray); break; } case LUA_TCCL: { linkgclist(gco2ccl(o), g->gray); break; } case LUA_TTABLE: { linkgclist(gco2t(o), g->gray); break; } case LUA_TTHREAD: { linkgclist(gco2th(o), g->gray); break; } case LUA_TPROTO: { linkgclist(gco2p(o), g->gray); break; } default: lua_assert(0); break; } }