C++ call_binTM函数代码示例

void luaV_concat (lua_State *L, int total, int last) {
  do {
    StkId top = L->base + last + 1;
    int n = 2;  /* number of elements handled in this pass (at least 2) */
    if (!tostring(L, top-2) || !tostring(L, top-1)) {
      if (!call_binTM(L, top-2, top-1, top-2, TM_CONCAT))
        luaG_concaterror(L, top-2, top-1);
    } else if (tsvalue(top-1)->tsv.len > 0) {  /* if len=0, do nothing */
      /* at least two string values; get as many as possible */
      lu_mem tl = cast(lu_mem, tsvalue(top-1)->tsv.len) +
                  cast(lu_mem, tsvalue(top-2)->tsv.len);
      char *buffer;
      int i;
      while (n < total && tostring(L, top-n-1)) {  /* collect total length */
        tl += tsvalue(top-n-1)->tsv.len;
        n++;
      }
      if (tl > MAX_SIZET) luaG_runerror(L, "string size overflow");
      buffer = luaZ_openspace(L, &G(L)->buff, tl);
      tl = 0;
      for (i=n; i>0; i--) {  /* concat all strings */
        size_t l = tsvalue(top-i)->tsv.len;
        memcpy(buffer+tl, svalue(top-i), l);
        tl += l;
      }
      setsvalue2s(top-n, luaS_newlstr(L, buffer, tl));
    }
    total -= n-1;  /* got `n' strings to create 1 new */
    last -= n-1;
  } while (total > 1);  /* repeat until only 1 result left */
}

static int call_orderTM (lua_State *L, const TValue *p1, const TValue *p2,
                         TMS event) {
  if (!call_binTM(L, p1, p2, L->top, event))
    return -1;  /* no metamethod */
  else
    return !l_isfalse(L->top);
}

static void Arith (lua_State *L, StkId ra, const TValue *rb,
                   const TValue *rc, TMS op) {
  TValue tempb, tempc;
  const TValue *b, *c;
  if ((b = luaV_tonumber(rb, &tempb)) != NULL &&
      (c = luaV_tonumber(rc, &tempc)) != NULL) {
    lua_Number nb = nvalue(b), nc = nvalue(c);
    switch (op) {
      case TM_ADD: setnvalue(ra, luai_numadd(nb, nc)); break;
      case TM_SUB: setnvalue(ra, luai_numsub(nb, nc)); break;
      case TM_MUL: setnvalue(ra, luai_nummul(nb, nc)); break;
      case TM_DIV: setnvalue(ra, luai_lnumdiv(nb, nc)); break;
      case TM_MOD: setnvalue(ra, luai_lnummod(nb, nc)); break;
      case TM_POW: setnvalue(ra, luai_numpow(nb, nc)); break;
      case TM_UNM: setnvalue(ra, luai_numunm(nb)); break;
      default: lua_assert(0); break;
    }
  }
  else {
    ptrdiff_t br = savestack(L, rb);
    ptrdiff_t cr = savestack(L, rc);
    if (!call_binTM(L, rb, rc, ra, op)) {
      luaG_aritherror(L, restorestack(L, br), restorestack(L, cr));
    }
  }
}

// [@ltm] 对参数栈上的参数执行concat操作
// total 需要concat的参数的个数
// last concat的数组最后一个元素下标
void luaV_concat (lua_State *L, int total, int last) {
  do {
    StkId top = L->base + last + 1;
    int n = 2;  /* number of elements handled in this pass (at least 2) */
    if (!tostring(L, top-2) || !tostring(L, top-1)) {
	  // 两个参数不全都是string，所以只能通过metamethod来处理
      if (!call_binTM(L, top-2, top-1, top-2, TM_CONCAT))
        luaG_concaterror(L, top-2, top-1);
    } else if (tsvalue(top-1)->len > 0) {  /* if len=0, do nothing<优化的套路呀> */
      /* at least two string values; get as many as possible */
      size_t tl = tsvalue(top-1)->len;
      char *buffer;
      int i;
      /* collect total length */
      for (n = 1; n < total && tostring(L, top-n-1); n++) {
        size_t l = tsvalue(top-n-1)->len;
        if (l >= MAX_SIZET - tl) luaG_runerror(L, "string length overflow");
        tl += l;
      }
	  // 这里保存了要concat的string的总大小
      buffer = luaZ_openspace(L, &G(L)->buff, tl);
      tl = 0;
      for (i=n; i>0; i--) {  /* concat all strings */
        size_t l = tsvalue(top-i)->len;
        memcpy(buffer+tl, svalue(top-i), l);
        tl += l;
      }
      setsvalue2s(L, top-n, luaS_newlstr(L, buffer, tl));
    }
    total -= n-1;  /* got `n' strings to create 1 new */
    last -= n-1;
  } while (total > 1);  /* repeat until only 1 result left */
}

void luaV_strconc (lua_State *L, int total, StkId top) {
  do {
    int n = 2;  /* number of elements handled in this pass (at least 2) */
    if (tostring(L, top-2) || tostring(L, top-1)) {
      if (!call_binTM(L, top, TM_CONCAT))
        luaG_binerror(L, top-2, LUA_TSTRING, "concat");
    }
    else if (tsvalue(top-1)->len > 0) {  /* if len=0, do nothing */
      /* at least two string values; get as many as possible */
      lint32 tl = (lint32)tsvalue(top-1)->len +
                  (lint32)tsvalue(top-2)->len;
      char *buffer;
      int i;
      while (n < total && !tostring(L, top-n-1)) {  /* collect total length */
        tl += tsvalue(top-n-1)->len;
        n++;
      }
      if (tl > MAX_SIZET) lua_error(L, "string size overflow");
      buffer = luaO_openspace(L, tl);
      tl = 0;
      for (i=n; i>0; i--) {  /* concat all strings */
        size_t l = tsvalue(top-i)->len;
        memcpy(buffer+tl, tsvalue(top-i)->str, l);
        tl += l;
      }
      tsvalue(top-n) = luaS_newlstr(L, buffer, tl);
    }
    total -= n-1;  /* got `n' strings to create 1 new */
    top -= n-1;
  } while (total > 1);  /* repeat until only 1 result left */
}

void luaV_concat (lua_State *L, int total, int last) {
  do {
    StkId top = L->base + last + 1;
    int n = 2;  /* number of elements handled in this pass (at least 2) */
    if (!(ttisstring(top-2) || ttisnumber(top-2)) || !tostring(L, top-1)) {
      if (!call_binTM(L, top-2, top-1, top-2, TM_CONCAT))
        luaG_concaterror(L, top-2, top-1);
    } else if (tsvalue(top-1)->len == 0)  /* second op is empty? */
      (void)tostring(L, top - 2);  /* result is first op (as string) */
    else {
      /* at least two string values; get as many as possible */
      size_t tl = tsvalue(top-1)->len;
      char *buffer;
      int i;
      /* collect total length */
      for (n = 1; n < total && tostring(L, top-n-1); n++) {
        size_t l = tsvalue(top-n-1)->len;
        if (l >= MAX_SIZET - tl) luaG_runerror(L, "string length overflow");
        tl += l;
      }
      buffer = luaZ_openspace(L, &G(L)->buff, tl);
      tl = 0;
      for (i=n; i>0; i--) {  /* concat all strings */
        size_t l = tsvalue(top-i)->len;
        memcpy(buffer+tl, svalue(top-i), l);
        tl += l;
      }
      setsvalue2s(L, top-n, luaS_newlstr(L, buffer, tl));
    }
    total -= n-1;  /* got `n' strings to create 1 new */
    last -= n-1;
  } while (total > 1);  /* repeat until only 1 result left */
}

static void Arith (lua_State *L, StkId ra,
                   const TObject *rb, const TObject *rc, TMS op) {
  TObject tempb, tempc;
  const TObject *b, *c;
  if ((b = luaV_tonumber(rb, &tempb)) != NULL &&
      (c = luaV_tonumber(rc, &tempc)) != NULL) {
    switch (op) {
      case TM_ADD: setnvalue(ra, nvalue(b) + nvalue(c)); break;
      case TM_SUB: setnvalue(ra, nvalue(b) - nvalue(c)); break;
      case TM_MUL: setnvalue(ra, nvalue(b) * nvalue(c)); break;
      case TM_DIV: setnvalue(ra, nvalue(b) / nvalue(c)); break;
      case TM_POW: {
        const TObject *f = luaH_getstr(hvalue(gt(L)), G(L)->tmname[TM_POW]);
        ptrdiff_t res = savestack(L, ra);
        if (!ttisfunction(f))
          luaG_runerror(L, "`__pow' (`^' operator) is not a function");
        callTMres(L, f, b, c);
        ra = restorestack(L, res);  /* previous call may change stack */
        setobjs2s(ra, L->top);
        break;
      }
      default: lua_assert(0); break;
    }
  }
  else if (!call_binTM(L, rb, rc, ra, op))
    luaG_aritherror(L, rb, rc);
}

void luaV_arith (lua_State *L, StkId ra, const TValue *rb,
                 const TValue *rc, TMS op) {
  TValue tempb, tempc;
  const TValue *b, *c;
  if ((b = luaV_tonumber(rb, &tempb)) != NULL &&
      (c = luaV_tonumber(rc, &tempc)) != NULL) {
    lua_Number res = luaO_arith(op - TM_ADD + LUA_OPADD, nvalue(b), nvalue(c));
    setnvalue(ra, res);
  }
  else if (!call_binTM(L, rb, rc, ra, op))
    luaG_aritherror(L, rb, rc);
}

int luaV_lessthan (lua_State *L, const TObject *l, const TObject *r, StkId top) {
  if (ttype(l) == LUA_TNUMBER && ttype(r) == LUA_TNUMBER)
    return (nvalue(l) < nvalue(r));
  else if (ttype(l) == LUA_TSTRING && ttype(r) == LUA_TSTRING)
    return (luaV_strcomp(tsvalue(l), tsvalue(r)) < 0);
  else {  /* call TM */
    luaD_checkstack(L, 2);
    *top++ = *l;
    *top++ = *r;
    if (!call_binTM(L, top, TM_LT))
      luaG_ordererror(L, top-2);
    L->top--;
    return (ttype(L->top) != LUA_TNIL);
  }
}

static void comparison(lua_Type ttype_less, lua_Type ttype_equal, lua_Type ttype_great, IMS op) {
	Stack *S = &lua_state->stack;
	TObject *l = S->top-2;
	TObject *r = S->top-1;
	int32 result;
	if (ttype(l) == LUA_T_NUMBER && ttype(r) == LUA_T_NUMBER)
		result = (nvalue(l) < nvalue(r)) ? -1 : (nvalue(l) == nvalue(r)) ? 0 : 1;
	else if (ttype(l) == LUA_T_STRING && ttype(r) == LUA_T_STRING)
		result = strcoll(svalue(l), svalue(r));
	else {
		call_binTM(op, "unexpected type in comparison");
		return;
	}
	S->top--;
	nvalue(S->top - 1) = 1;
	ttype(S->top - 1) = (result < 0) ? ttype_less : (result == 0) ? ttype_equal : ttype_great;
}

void luaV_concat (lua_State *L, int total, int last) {
  lu_mem max_sizet = MAX_SIZET;
  if (G(L)->memlimit < max_sizet) max_sizet = G(L)->memlimit;
  do {
    /* Any call which does a memory allocation may trim the stack,
       invalidating top unless the stack is fixed duri  ng the allocation */ 
    StkId top = L->base + last + 1;
    fixedstack(L);
    int n = 2;  /* number of elements handled in this pass (at least 2) */
    if (!(ttisstring(top-2) || ttisnumber(top-2)) || !tostring(L, top-1)) {
      unfixedstack(L);
      if (!call_binTM(L, top-2, top-1, top-2, TM_CONCAT)) {
        /* restore 'top' pointer, since stack might have been reallocted */
        top = L->base + last + 1;
        luaG_concaterror(L, top-2, top-1);
      }
    } else if (tsvalue(top-1)->len == 0) { /* second op is empty? */
      (void)tostring(L, top - 2);  /* result is first op (as string) */
    } else {
      /* at least two string values; get as many as possible */
      size_t tl = tsvalue(top-1)->len;
      char *buffer;
      int i;
      /* collect total length */
      for (n = 1; n < total && tostring(L, top-n-1); n++) {
        size_t l = tsvalue(top-n-1)->len;
        if (l >= max_sizet - tl) luaG_runerror(L, "string length overflow");
        tl += l;
      }
      G(L)->buff.n = tl;
      buffer = luaZ_openspace(L, &G(L)->buff, tl);
      tl = 0;
      for (i=n; i>0; i--) {  /* concat all strings */
        size_t l = tsvalue(top-i)->len;
        c_memcpy(buffer+tl, svalue(top-i), l);
        tl += l;
      }
      setsvalue2s(L, top-n, luaS_newlstr(L, buffer, tl));
      luaZ_resetbuffer(&G(L)->buff);
    }
    total -= n-1;  /* got `n' strings to create 1 new */
    last -= n-1;
    unfixedstack(L);
  } while (total > 1);  /* repeat until only 1 result left */
}

static void comparison (lua_Type ttype_less, lua_Type ttype_equal, 
                        lua_Type ttype_great, IMS op)
{
  TObject *l = top-2;
  TObject *r = top-1;
  int result;
  if (ttype(l) == LUA_T_NUMBER && ttype(r) == LUA_T_NUMBER)
    result = (nvalue(l) < nvalue(r)) ? -1 : (nvalue(l) == nvalue(r)) ? 0 : 1;
  else if (ttype(l) == LUA_T_STRING && ttype(r) == LUA_T_STRING)
    result = strcmp(svalue(l), svalue(r));
  else {
    call_binTM(op, "unexpected type at comparison");
    return;
  }
  top--;
  nvalue(top-1) = 1;
  ttype(top-1) = (result < 0) ? ttype_less :
                                (result == 0) ? ttype_equal : ttype_great;
}

void luaV_concat (lua_State *L, int total) {
  lua_assert(total >= 2);
  do {
    StkId top = L->top;
    int n = 2;  /* number of elements handled in this pass (at least 2) */
    if (!(ttisstring(top-2) || ttisnumber(top-2)) || !tostring(L, top-1)) {
      if (!call_binTM(L, top-2, top-1, top-2, TM_CONCAT))
        luaG_concaterror(L, top-2, top-1);
    }
    else if (tsvalue(top-1)->len == 0)  /* second operand is empty? */
      (void)tostring(L, top - 2);  /* result is first operand */
    else if (ttisstring(top-2) && tsvalue(top-2)->len == 0) {
      setsvalue2s(L, top-2, rawtsvalue(top-1));  /* result is second op. */
    }
    else {
      /* at least two non-empty string values; get as many as possible */
      size_t tl = tsvalue(top-1)->len;
      char *buffer;
      int i;
      /* collect total length */
      for (i = 1; i < total && tostring(L, top-i-1); i++) {
        size_t l = tsvalue(top-i-1)->len;
        if (l >= (MAX_SIZET/sizeof(char)) - tl)
          luaG_runerror(L, "string length overflow");
        tl += l;
      }
      buffer = luaZ_openspace(L, &G(L)->buff, tl);
      tl = 0;
      n = i;
      do {  /* concat all strings */
        size_t l = tsvalue(top-i)->len;
        memcpy(buffer+tl, svalue(top-i), l * sizeof(char));
        tl += l;
      } while (--i > 0);
      setsvalue2s(L, top-n, luaS_newlstr(L, buffer, tl));
    }
    total -= n-1;  /* got 'n' strings to create 1 new */
    L->top -= n-1;  /* popped 'n' strings and pushed one */
  } while (total > 1);  /* repeat until only 1 result left */
}

static void Logic (lua_State *L, StkId ra, const TValue *rb,
                   const TValue *rc, TMS op) {
  TValue tempb, tempc;
  const TValue *b, *c;
  if ((b = luaV_tonumber(rb, &tempb)) != NULL &&
      (c = luaV_tonumber(rc, &tempc)) != NULL) {
    lua_Number nb = nvalue(b), nc = nvalue(c);
    lua_Integer r;
    switch (op) {
      case TM_BLSHFT: luai_loglshft(r, nb, nc); break;
      case TM_BRSHFT: luai_logrshft(r, nb, nc); break;
      case TM_BOR: luai_logor(r, nb, nc); break;
      case TM_BAND: luai_logand(r, nb, nc); break;
      case TM_BXOR: luai_logxor(r, nb, nc); break;
      case TM_BNOT: luai_lognot(r, nb); break;
      default: lua_assert(0); r = 0; break;
    }
    setnvalue(ra, r);
  }
  else if (!call_binTM(L, rb, rc, ra, op))
    luaG_logicerror(L, rb, rc);
}

static void Arith (lua_State *L, StkId ra, const TValue *rb,
                   const TValue *rc, TMS op) {
  TValue tempb, tempc;
  const TValue *b, *c;
  if ((b = luaV_tonumber(rb, &tempb)) != NULL &&
      (c = luaV_tonumber(rc, &tempc)) != NULL) {
    lua_Number nb = nvalue(b), nc = nvalue(c);
    switch (op) {
      case TM_ADD: setnvalue(ra, luai_numadd(nb, nc)); break;
      case TM_SUB: setnvalue(ra, luai_numsub(nb, nc)); break;
      case TM_MUL: setnvalue(ra, luai_nummul(nb, nc)); break;
      case TM_DIV: setnvalue(ra, luai_numdiv(nb, nc)); break;
      case TM_MOD: setnvalue(ra, luai_nummod(nb, nc)); break;
      case TM_POW: setnvalue(ra, luai_numpow(nb, nc)); break;
      case TM_UNM: setnvalue(ra, luai_numunm(nb)); break;
#if defined(LUA_BITWISE_OPERATORS)
      case TM_INTDIV: setnvalue(ra, luai_numintdiv(nb, nc)); break;
#endif
      default: lua_assert(0); break;
    }
  }
  else if (!call_binTM(L, rb, rc, ra, op))
    luaG_aritherror(L, rb, rc);
}