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1866
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1 /*
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2 ** $Id: ltm.c,v 2.14 2011/06/02 19:31:40 roberto Exp $
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3 ** Tag methods
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4 ** See Copyright Notice in lua.h
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5 */
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6
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7
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8 #include <string.h>
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9
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10 #define ltm_c
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11 #define LUA_CORE
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12
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13 #include "lua.h"
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14
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15 #include "lobject.h"
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16 #include "lstate.h"
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17 #include "lstring.h"
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18 #include "ltable.h"
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19 #include "ltm.h"
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20
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21
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22 static const char udatatypename[] = "userdata";
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23
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24 LUAI_DDEF const char *const luaT_typenames_[LUA_TOTALTAGS] = {
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25 "no value",
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26 "nil", "boolean", udatatypename, "number",
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27 "string", "table", "function", udatatypename, "thread",
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28 "proto", "upval" /* these last two cases are used for tests only */
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29 };
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30
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31
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32 void luaT_init (lua_State *L) {
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33 static const char *const luaT_eventname[] = { /* ORDER TM */
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34 "__index", "__newindex",
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35 "__gc", "__mode", "__len", "__eq",
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36 "__add", "__sub", "__mul", "__div", "__mod",
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37 "__pow", "__unm", "__lt", "__le",
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38 "__concat", "__call"
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39 };
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40 int i;
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41 for (i=0; i<TM_N; i++) {
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42 G(L)->tmname[i] = luaS_new(L, luaT_eventname[i]);
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43 luaS_fix(G(L)->tmname[i]); /* never collect these names */
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44 }
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45 }
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46
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47
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48 /*
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49 ** function to be used with macro "fasttm": optimized for absence of
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50 ** tag methods
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51 */
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52 const TValue *luaT_gettm (Table *events, TMS event, TString *ename) {
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53 const TValue *tm = luaH_getstr(events, ename);
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54 lua_assert(event <= TM_EQ);
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55 if (ttisnil(tm)) { /* no tag method? */
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56 events->flags |= cast_byte(1u<<event); /* cache this fact */
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57 return NULL;
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58 }
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59 else return tm;
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60 }
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61
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62
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63 const TValue *luaT_gettmbyobj (lua_State *L, const TValue *o, TMS event) {
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64 Table *mt;
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65 switch (ttypenv(o)) {
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66 case LUA_TTABLE:
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67 mt = hvalue(o)->metatable;
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68 break;
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69 case LUA_TUSERDATA:
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70 mt = uvalue(o)->metatable;
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71 break;
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72 default:
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73 mt = G(L)->mt[ttypenv(o)];
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74 }
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75 return (mt ? luaH_getstr(mt, G(L)->tmname[event]) : luaO_nilobject);
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76 }
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77
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