Function luaK_indexed

third-party/lua-5.5.0/src/lcode.c:1357–1391

** Create expression 't[k]'. 't' must have its final result already in a ** register or upvalue. Upvalues can only be indexed by literal strings. ** Keys can be literal strings in the constant table or arbitrary ** values in registers. */

** values in registers.
*/
void luaK_indexed (FuncState *fs, expdesc *t, expdesc *k) {
  int keystr = -1;
  if (k->k == VKSTR)
    keystr = str2K(fs, k);
  lua_assert(!hasjumps(t) &&
             (t->k == VLOCAL || t->k == VVARGVAR ||
              t->k == VNONRELOC || t->k == VUPVAL));
  if (t->k == VUPVAL && !isKstr(fs, k))  /* upvalue indexed by non 'Kstr'? */
    luaK_exp2anyreg(fs, t);  /* put it in a register */
  if (t->k == VUPVAL) {
    lu_byte temp = cast_byte(t->u.info);  /* upvalue index */
    t->u.ind.t = temp;  /* (can't do a direct assignment; values overlap) */
    lua_assert(isKstr(fs, k));
    fillidxk(t, k->u.info, VINDEXUP);  /* literal short string */
  }
  else if (t->k == VVARGVAR) {  /* indexing the vararg parameter? */
    int kreg = luaK_exp2anyreg(fs, k);  /* put key in some register */
    lu_byte vreg = cast_byte(t->u.var.ridx);  /* register with vararg param. */
    lua_assert(vreg == fs->f->numparams);
    t->u.ind.t = vreg;  /* (avoid a direct assignment; values may overlap) */
    fillidxk(t, kreg, VVARGIND);  /* 't' represents 'vararg[k]' */
  }
  else {
    /* register index of the table */
    t->u.ind.t = cast_byte((t->k == VLOCAL) ? t->u.var.ridx: t->u.info);
    if (isKstr(fs, k))
      fillidxk(t, k->u.info, VINDEXSTR);  /* literal short string */
    else if (isCint(k))  /* int. constant in proper range? */
      fillidxk(t, cast_int(k->u.ival), VINDEXI);
    else
      fillidxk(t, luaK_exp2anyreg(fs, k), VINDEXED);  /* register */
  }
  t->u.ind.keystr = keystr;  /* string index in 'k' */
  t->u.ind.ro = 0;  /* by default, not read-only */
}


/*