1 /* 2 ** $Id: ltm.c,v 2.38.1.1 2017/04/19 17:39:34 roberto Exp $ 3 ** Tag methods 4 ** See Copyright Notice in lua.h 5 */ 6 7 #define ltm_c 8 #define LUA_CORE 9 10 #include "lprefix.h" 11 12 13 #include <string.h> 14 15 #include "lua.h" 16 17 #include "ldebug.h" 18 #include "ldo.h" 19 #include "lobject.h" 20 #include "lstate.h" 21 #include "lstring.h" 22 #include "ltable.h" 23 #include "ltm.h" 24 #include "lvm.h" 25 26 27 static const char udatatypename[] = "userdata"; 28 29 LUAI_DDEF const char *const luaT_typenames_[LUA_TOTALTAGS] = { 30 "no value", 31 "nil", "boolean", udatatypename, "number", 32 "string", "table", "function", udatatypename, "thread", 33 "proto" /* this last case is used for tests only */ 34 }; 35 36 37 void luaT_init (lua_State *L) { 38 static const char *const luaT_eventname[] = { /* ORDER TM */ 39 "__index", "__newindex", 40 "__gc", "__mode", "__len", "__eq", 41 "__add", "__sub", "__mul", "__mod", "__pow", 42 "__div", "__idiv", 43 "__band", "__bor", "__bxor", "__shl", "__shr", 44 "__unm", "__bnot", "__lt", "__le", 45 "__concat", "__call" 46 }; 47 int i; 48 for (i=0; i<TM_N; i++) { 49 G(L)->tmname[i] = luaS_new(L, luaT_eventname[i]); 50 luaC_fix(L, obj2gco(G(L)->tmname[i])); /* never collect these names */ 51 } 52 } 53 54 55 /* 56 ** function to be used with macro "fasttm": optimized for absence of 57 ** tag methods 58 */ 59 const TValue *luaT_gettm (Table *events, TMS event, TString *ename) { 60 const TValue *tm = luaH_getshortstr(events, ename); 61 lua_assert(event <= TM_EQ); 62 if (ttisnil(tm)) { /* no tag method? */ 63 events->flags |= cast_byte(1u<<event); /* cache this fact */ 64 return NULL; 65 } 66 else return tm; 67 } 68 69 70 const TValue *luaT_gettmbyobj (lua_State *L, const TValue *o, TMS event) { 71 Table *mt; 72 switch (ttnov(o)) { 73 case LUA_TTABLE: 74 mt = hvalue(o)->metatable; 75 break; 76 case LUA_TUSERDATA: 77 mt = uvalue(o)->metatable; 78 break; 79 default: 80 mt = G(L)->mt[ttnov(o)]; 81 } 82 return (mt ? luaH_getshortstr(mt, G(L)->tmname[event]) : luaO_nilobject); 83 } 84 85 86 /* 87 ** Return the name of the type of an object. For tables and userdata 88 ** with metatable, use their '__name' metafield, if present. 89 */ 90 const char *luaT_objtypename (lua_State *L, const TValue *o) { 91 Table *mt; 92 if ((ttistable(o) && (mt = hvalue(o)->metatable) != NULL) || 93 (ttisfulluserdata(o) && (mt = uvalue(o)->metatable) != NULL)) { 94 const TValue *name = luaH_getshortstr(mt, luaS_new(L, "__name")); 95 if (ttisstring(name)) /* is '__name' a string? */ 96 return getstr(tsvalue(name)); /* use it as type name */ 97 } 98 return ttypename(ttnov(o)); /* else use standard type name */ 99 } 100 101 102 void luaT_callTM (lua_State *L, const TValue *f, const TValue *p1, 103 const TValue *p2, TValue *p3, int hasres) { 104 ptrdiff_t result = savestack(L, p3); 105 StkId func = L->top; 106 setobj2s(L, func, f); /* push function (assume EXTRA_STACK) */ 107 setobj2s(L, func + 1, p1); /* 1st argument */ 108 setobj2s(L, func + 2, p2); /* 2nd argument */ 109 L->top += 3; 110 if (!hasres) /* no result? 'p3' is third argument */ 111 setobj2s(L, L->top++, p3); /* 3rd argument */ 112 /* metamethod may yield only when called from Lua code */ 113 if (isLua(L->ci)) 114 luaD_call(L, func, hasres); 115 else 116 luaD_callnoyield(L, func, hasres); 117 if (hasres) { /* if has result, move it to its place */ 118 p3 = restorestack(L, result); 119 setobjs2s(L, p3, --L->top); 120 } 121 } 122 123 124 int luaT_callbinTM (lua_State *L, const TValue *p1, const TValue *p2, 125 StkId res, TMS event) { 126 const TValue *tm = luaT_gettmbyobj(L, p1, event); /* try first operand */ 127 if (ttisnil(tm)) 128 tm = luaT_gettmbyobj(L, p2, event); /* try second operand */ 129 if (ttisnil(tm)) return 0; 130 luaT_callTM(L, tm, p1, p2, res, 1); 131 return 1; 132 } 133 134 135 void luaT_trybinTM (lua_State *L, const TValue *p1, const TValue *p2, 136 StkId res, TMS event) { 137 if (!luaT_callbinTM(L, p1, p2, res, event)) { 138 switch (event) { 139 case TM_CONCAT: 140 luaG_concaterror(L, p1, p2); 141 /* call never returns, but to avoid warnings: *//* FALLTHROUGH */ 142 case TM_BAND: case TM_BOR: case TM_BXOR: 143 case TM_SHL: case TM_SHR: case TM_BNOT: { 144 lua_Number dummy; 145 if (tonumber(p1, &dummy) && tonumber(p2, &dummy)) 146 luaG_tointerror(L, p1, p2); 147 else 148 luaG_opinterror(L, p1, p2, "perform bitwise operation on"); 149 } 150 /* calls never return, but to avoid warnings: *//* FALLTHROUGH */ 151 default: 152 luaG_opinterror(L, p1, p2, "perform arithmetic on"); 153 } 154 } 155 } 156 157 158 int luaT_callorderTM (lua_State *L, const TValue *p1, const TValue *p2, 159 TMS event) { 160 if (!luaT_callbinTM(L, p1, p2, L->top, event)) 161 return -1; /* no metamethod */ 162 else 163 return !l_isfalse(L->top); 164 } 165 166