150 lines
4.0 KiB
C
150 lines
4.0 KiB
C
/*
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** $Id: ltm.c,v 2.36 2015/11/03 15:47:30 roberto Exp $
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** Tag methods
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** See Copyright Notice in lua.h
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*/
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#define ltm_c
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#define LUA_CORE
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#include "lprefix.h"
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#include <string.h>
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#include "lua.h"
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#include "ldebug.h"
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#include "ldo.h"
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#include "lobject.h"
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#include "lstate.h"
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#include "lstring.h"
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#include "ltable.h"
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#include "ltm.h"
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#include "lvm.h"
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static const char udatatypename[] = "userdata";
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LUAI_DDEF const char *const luaT_typenames_[LUA_TOTALTAGS] = {
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"no value",
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"nil", "boolean", udatatypename, "number",
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"string", "table", "function", udatatypename, "thread",
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"proto" /* this last case is used for tests only */
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};
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void luaT_init (lua_State *L) {
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static const char *const luaT_eventname[] = { /* ORDER TM */
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"__index", "__newindex",
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"__gc", "__mode", "__len", "__eq",
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"__add", "__sub", "__mul", "__mod", "__pow",
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"__div", "__idiv",
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"__band", "__bor", "__bxor", "__shl", "__shr",
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"__unm", "__bnot", "__lt", "__le",
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"__concat", "__call"
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};
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int i;
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for (i=0; i<TM_N; i++) {
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G(L)->tmname[i] = luaS_new(L, luaT_eventname[i]);
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luaC_fix(L, obj2gco(G(L)->tmname[i])); /* never collect these names */
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}
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}
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/*
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** function to be used with macro "fasttm": optimized for absence of
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** tag methods
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*/
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const TValue *luaT_gettm (Table *events, TMS event, TString *ename) {
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const TValue *tm = luaH_getshortstr(events, ename);
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lua_assert(event <= TM_EQ);
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if (ttisnil(tm)) { /* no tag method? */
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events->flags |= cast_byte(1u<<event); /* cache this fact */
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return NULL;
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}
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else return tm;
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}
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const TValue *luaT_gettmbyobj (lua_State *L, const TValue *o, TMS event) {
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Table *mt;
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switch (ttnov(o)) {
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case LUA_TTABLE:
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mt = hvalue(o)->metatable;
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break;
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case LUA_TUSERDATA:
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mt = uvalue(o)->metatable;
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break;
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default:
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mt = G(L)->mt[ttnov(o)];
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}
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return (mt ? luaH_getshortstr(mt, G(L)->tmname[event]) : luaO_nilobject);
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}
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void luaT_callTM (lua_State *L, const TValue *f, const TValue *p1,
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const TValue *p2, TValue *p3, int hasres) {
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ptrdiff_t result = savestack(L, p3);
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StkId func = L->top;
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setobj2s(L, func, f); /* push function (assume EXTRA_STACK) */
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setobj2s(L, func + 1, p1); /* 1st argument */
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setobj2s(L, func + 2, p2); /* 2nd argument */
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L->top += 3;
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if (!hasres) /* no result? 'p3' is third argument */
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setobj2s(L, L->top++, p3); /* 3rd argument */
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/* metamethod may yield only when called from Lua code */
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if (isLua(L->ci))
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luaD_call(L, func, hasres);
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else
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luaD_callnoyield(L, func, hasres);
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if (hasres) { /* if has result, move it to its place */
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p3 = restorestack(L, result);
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setobjs2s(L, p3, --L->top);
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}
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}
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int luaT_callbinTM (lua_State *L, const TValue *p1, const TValue *p2,
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StkId res, TMS event) {
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const TValue *tm = luaT_gettmbyobj(L, p1, event); /* try first operand */
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if (ttisnil(tm))
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tm = luaT_gettmbyobj(L, p2, event); /* try second operand */
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if (ttisnil(tm)) return 0;
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luaT_callTM(L, tm, p1, p2, res, 1);
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return 1;
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}
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void luaT_trybinTM (lua_State *L, const TValue *p1, const TValue *p2,
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StkId res, TMS event) {
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if (!luaT_callbinTM(L, p1, p2, res, event)) {
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switch (event) {
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case TM_CONCAT:
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luaG_concaterror(L, p1, p2);
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/* call never returns, but to avoid warnings: *//* FALLTHROUGH */
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case TM_BAND: case TM_BOR: case TM_BXOR:
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case TM_SHL: case TM_SHR: case TM_BNOT: {
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lua_Number dummy;
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if (tonumber(p1, &dummy) && tonumber(p2, &dummy))
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luaG_tointerror(L, p1, p2);
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else
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luaG_opinterror(L, p1, p2, "perform bitwise operation on");
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}
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/* calls never return, but to avoid warnings: *//* FALLTHROUGH */
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default:
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luaG_opinterror(L, p1, p2, "perform arithmetic on");
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}
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}
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}
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int luaT_callorderTM (lua_State *L, const TValue *p1, const TValue *p2,
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TMS event) {
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if (!luaT_callbinTM(L, p1, p2, L->top, event))
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return -1; /* no metamethod */
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else
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return !l_isfalse(L->top);
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}
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