1 // Copyright 2006-2008 the V8 project authors. All rights reserved. 2 // Redistribution and use in source and binary forms, with or without 3 // modification, are permitted provided that the following conditions are 4 // met: 5 // 6 // * Redistributions of source code must retain the above copyright 7 // notice, this list of conditions and the following disclaimer. 8 // * Redistributions in binary form must reproduce the above 9 // copyright notice, this list of conditions and the following 10 // disclaimer in the documentation and/or other materials provided 11 // with the distribution. 12 // * Neither the name of Google Inc. nor the names of its 13 // contributors may be used to endorse or promote products derived 14 // from this software without specific prior written permission. 15 // 16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 17 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 18 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 19 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 20 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 21 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 28 // This files contains runtime support implemented in JavaScript. 29 30 // CAUTION: Some of the functions specified in this file are called 31 // directly from compiled code. These are the functions with names in 32 // ALL CAPS. The compiled code passes the first argument in 'this' and 33 // it does not push the function onto the stack. This means that you 34 // cannot use contexts in all these functions. 35 36 37 /* ----------------------------------- 38 - - - C o m p a r i s o n - - - 39 ----------------------------------- 40 */ 41 42 // The following declarations are shared with other native JS files. 43 // They are all declared at this one spot to avoid redeclaration errors. 44 var $Object = global.Object; 45 var $Array = global.Array; 46 var $String = global.String; 47 var $Number = global.Number; 48 var $Function = global.Function; 49 var $Boolean = global.Boolean; 50 var $NaN = %GetRootNaN(); 51 var builtins = this; 52 53 // ECMA-262 Section 11.9.3. 54 function EQUALS(y) { 55 if (IS_STRING(this) && IS_STRING(y)) return %StringEquals(this, y); 56 var x = this; 57 58 while (true) { 59 if (IS_NUMBER(x)) { 60 while (true) { 61 if (IS_NUMBER(y)) return %NumberEquals(x, y); 62 if (IS_NULL_OR_UNDEFINED(y)) return 1; // not equal 63 if (!IS_SPEC_OBJECT(y)) { 64 // String or boolean. 65 return %NumberEquals(x, %ToNumber(y)); 66 } 67 y = %ToPrimitive(y, NO_HINT); 68 } 69 } else if (IS_STRING(x)) { 70 while (true) { 71 if (IS_STRING(y)) return %StringEquals(x, y); 72 if (IS_NUMBER(y)) return %NumberEquals(%ToNumber(x), y); 73 if (IS_BOOLEAN(y)) return %NumberEquals(%ToNumber(x), %ToNumber(y)); 74 if (IS_NULL_OR_UNDEFINED(y)) return 1; // not equal 75 y = %ToPrimitive(y, NO_HINT); 76 } 77 } else if (IS_BOOLEAN(x)) { 78 if (IS_BOOLEAN(y)) return %_ObjectEquals(x, y) ? 0 : 1; 79 if (IS_NULL_OR_UNDEFINED(y)) return 1; 80 if (IS_NUMBER(y)) return %NumberEquals(%ToNumber(x), y); 81 if (IS_STRING(y)) return %NumberEquals(%ToNumber(x), %ToNumber(y)); 82 // y is object. 83 x = %ToNumber(x); 84 y = %ToPrimitive(y, NO_HINT); 85 } else if (IS_NULL_OR_UNDEFINED(x)) { 86 return IS_NULL_OR_UNDEFINED(y) ? 0 : 1; 87 } else { 88 // x is an object. 89 if (IS_SPEC_OBJECT(y)) { 90 return %_ObjectEquals(x, y) ? 0 : 1; 91 } 92 if (IS_NULL_OR_UNDEFINED(y)) return 1; // not equal 93 if (IS_BOOLEAN(y)) y = %ToNumber(y); 94 x = %ToPrimitive(x, NO_HINT); 95 } 96 } 97 } 98 99 // ECMA-262, section 11.9.4, page 56. 100 function STRICT_EQUALS(x) { 101 if (IS_STRING(this)) { 102 if (!IS_STRING(x)) return 1; // not equal 103 return %StringEquals(this, x); 104 } 105 106 if (IS_NUMBER(this)) { 107 if (!IS_NUMBER(x)) return 1; // not equal 108 return %NumberEquals(this, x); 109 } 110 111 // If anything else gets here, we just do simple identity check. 112 // Objects (including functions), null, undefined and booleans were 113 // checked in the CompareStub, so there should be nothing left. 114 return %_ObjectEquals(this, x) ? 0 : 1; 115 } 116 117 118 // ECMA-262, section 11.8.5, page 53. The 'ncr' parameter is used as 119 // the result when either (or both) the operands are NaN. 120 function COMPARE(x, ncr) { 121 var left; 122 var right; 123 // Fast cases for string, numbers and undefined compares. 124 if (IS_STRING(this)) { 125 if (IS_STRING(x)) return %_StringCompare(this, x); 126 if (IS_UNDEFINED(x)) return ncr; 127 left = this; 128 } else if (IS_NUMBER(this)) { 129 if (IS_NUMBER(x)) return %NumberCompare(this, x, ncr); 130 if (IS_UNDEFINED(x)) return ncr; 131 left = this; 132 } else if (IS_UNDEFINED(this)) { 133 if (!IS_UNDEFINED(x)) { 134 %ToPrimitive(x, NUMBER_HINT); 135 } 136 return ncr; 137 } else if (IS_UNDEFINED(x)) { 138 %ToPrimitive(this, NUMBER_HINT); 139 return ncr; 140 } else { 141 left = %ToPrimitive(this, NUMBER_HINT); 142 } 143 144 right = %ToPrimitive(x, NUMBER_HINT); 145 if (IS_STRING(left) && IS_STRING(right)) { 146 return %_StringCompare(left, right); 147 } else { 148 var left_number = %ToNumber(left); 149 var right_number = %ToNumber(right); 150 if (NUMBER_IS_NAN(left_number) || NUMBER_IS_NAN(right_number)) return ncr; 151 return %NumberCompare(left_number, right_number, ncr); 152 } 153 } 154 155 156 157 /* ----------------------------------- 158 - - - A r i t h m e t i c - - - 159 ----------------------------------- 160 */ 161 162 // ECMA-262, section 11.6.1, page 50. 163 function ADD(x) { 164 // Fast case: Check for number operands and do the addition. 165 if (IS_NUMBER(this) && IS_NUMBER(x)) return %NumberAdd(this, x); 166 if (IS_STRING(this) && IS_STRING(x)) return %_StringAdd(this, x); 167 168 // Default implementation. 169 var a = %ToPrimitive(this, NO_HINT); 170 var b = %ToPrimitive(x, NO_HINT); 171 172 if (IS_STRING(a)) { 173 return %_StringAdd(a, %ToString(b)); 174 } else if (IS_STRING(b)) { 175 return %_StringAdd(%NonStringToString(a), b); 176 } else { 177 return %NumberAdd(%ToNumber(a), %ToNumber(b)); 178 } 179 } 180 181 182 // Left operand (this) is already a string. 183 function STRING_ADD_LEFT(y) { 184 if (!IS_STRING(y)) { 185 if (IS_STRING_WRAPPER(y) && %_IsStringWrapperSafeForDefaultValueOf(y)) { 186 y = %_ValueOf(y); 187 } else { 188 y = IS_NUMBER(y) 189 ? %_NumberToString(y) 190 : %ToString(%ToPrimitive(y, NO_HINT)); 191 } 192 } 193 return %_StringAdd(this, y); 194 } 195 196 197 // Right operand (y) is already a string. 198 function STRING_ADD_RIGHT(y) { 199 var x = this; 200 if (!IS_STRING(x)) { 201 if (IS_STRING_WRAPPER(x) && %_IsStringWrapperSafeForDefaultValueOf(x)) { 202 x = %_ValueOf(x); 203 } else { 204 x = IS_NUMBER(x) 205 ? %_NumberToString(x) 206 : %ToString(%ToPrimitive(x, NO_HINT)); 207 } 208 } 209 return %_StringAdd(x, y); 210 } 211 212 213 // ECMA-262, section 11.6.2, page 50. 214 function SUB(y) { 215 var x = IS_NUMBER(this) ? this : %NonNumberToNumber(this); 216 if (!IS_NUMBER(y)) y = %NonNumberToNumber(y); 217 return %NumberSub(x, y); 218 } 219 220 221 // ECMA-262, section 11.5.1, page 48. 222 function MUL(y) { 223 var x = IS_NUMBER(this) ? this : %NonNumberToNumber(this); 224 if (!IS_NUMBER(y)) y = %NonNumberToNumber(y); 225 return %NumberMul(x, y); 226 } 227 228 229 // ECMA-262, section 11.5.2, page 49. 230 function DIV(y) { 231 var x = IS_NUMBER(this) ? this : %NonNumberToNumber(this); 232 if (!IS_NUMBER(y)) y = %NonNumberToNumber(y); 233 return %NumberDiv(x, y); 234 } 235 236 237 // ECMA-262, section 11.5.3, page 49. 238 function MOD(y) { 239 var x = IS_NUMBER(this) ? this : %NonNumberToNumber(this); 240 if (!IS_NUMBER(y)) y = %NonNumberToNumber(y); 241 return %NumberMod(x, y); 242 } 243 244 245 246 /* ------------------------------------------- 247 - - - B i t o p e r a t i o n s - - - 248 ------------------------------------------- 249 */ 250 251 // ECMA-262, section 11.10, page 57. 252 function BIT_OR(y) { 253 var x = IS_NUMBER(this) ? this : %NonNumberToNumber(this); 254 if (!IS_NUMBER(y)) y = %NonNumberToNumber(y); 255 return %NumberOr(x, y); 256 } 257 258 259 // ECMA-262, section 11.10, page 57. 260 function BIT_AND(y) { 261 var x; 262 if (IS_NUMBER(this)) { 263 x = this; 264 if (!IS_NUMBER(y)) y = %NonNumberToNumber(y); 265 } else { 266 x = %NonNumberToNumber(this); 267 // Make sure to convert the right operand to a number before 268 // bailing out in the fast case, but after converting the 269 // left operand. This ensures that valueOf methods on the right 270 // operand are always executed. 271 if (!IS_NUMBER(y)) y = %NonNumberToNumber(y); 272 // Optimize for the case where we end up AND'ing a value 273 // that doesn't convert to a number. This is common in 274 // certain benchmarks. 275 if (NUMBER_IS_NAN(x)) return 0; 276 } 277 return %NumberAnd(x, y); 278 } 279 280 281 // ECMA-262, section 11.10, page 57. 282 function BIT_XOR(y) { 283 var x = IS_NUMBER(this) ? this : %NonNumberToNumber(this); 284 if (!IS_NUMBER(y)) y = %NonNumberToNumber(y); 285 return %NumberXor(x, y); 286 } 287 288 289 // ECMA-262, section 11.4.7, page 47. 290 function UNARY_MINUS() { 291 var x = IS_NUMBER(this) ? this : %NonNumberToNumber(this); 292 return %NumberUnaryMinus(x); 293 } 294 295 296 // ECMA-262, section 11.4.8, page 48. 297 function BIT_NOT() { 298 var x = IS_NUMBER(this) ? this : %NonNumberToNumber(this); 299 return %NumberNot(x); 300 } 301 302 303 // ECMA-262, section 11.7.1, page 51. 304 function SHL(y) { 305 var x = IS_NUMBER(this) ? this : %NonNumberToNumber(this); 306 if (!IS_NUMBER(y)) y = %NonNumberToNumber(y); 307 return %NumberShl(x, y); 308 } 309 310 311 // ECMA-262, section 11.7.2, page 51. 312 function SAR(y) { 313 var x; 314 if (IS_NUMBER(this)) { 315 x = this; 316 if (!IS_NUMBER(y)) y = %NonNumberToNumber(y); 317 } else { 318 x = %NonNumberToNumber(this); 319 // Make sure to convert the right operand to a number before 320 // bailing out in the fast case, but after converting the 321 // left operand. This ensures that valueOf methods on the right 322 // operand are always executed. 323 if (!IS_NUMBER(y)) y = %NonNumberToNumber(y); 324 // Optimize for the case where we end up shifting a value 325 // that doesn't convert to a number. This is common in 326 // certain benchmarks. 327 if (NUMBER_IS_NAN(x)) return 0; 328 } 329 return %NumberSar(x, y); 330 } 331 332 333 // ECMA-262, section 11.7.3, page 52. 334 function SHR(y) { 335 var x = IS_NUMBER(this) ? this : %NonNumberToNumber(this); 336 if (!IS_NUMBER(y)) y = %NonNumberToNumber(y); 337 return %NumberShr(x, y); 338 } 339 340 341 342 /* ----------------------------- 343 - - - H e l p e r s - - - 344 ----------------------------- 345 */ 346 347 // ECMA-262, section 11.4.1, page 46. 348 function DELETE(key, strict) { 349 return %DeleteProperty(%ToObject(this), %ToString(key), strict); 350 } 351 352 353 // ECMA-262, section 11.8.7, page 54. 354 function IN(x) { 355 if (!IS_SPEC_OBJECT(x)) { 356 throw %MakeTypeError('invalid_in_operator_use', [this, x]); 357 } 358 return %_IsNonNegativeSmi(this) ? 359 %HasElement(x, this) : %HasProperty(x, %ToString(this)); 360 } 361 362 363 // ECMA-262, section 11.8.6, page 54. To make the implementation more 364 // efficient, the return value should be zero if the 'this' is an 365 // instance of F, and non-zero if not. This makes it possible to avoid 366 // an expensive ToBoolean conversion in the generated code. 367 function INSTANCE_OF(F) { 368 var V = this; 369 if (!IS_SPEC_FUNCTION(F)) { 370 throw %MakeTypeError('instanceof_function_expected', [V]); 371 } 372 373 // If V is not an object, return false. 374 if (!IS_SPEC_OBJECT(V)) { 375 return 1; 376 } 377 378 // Check if function is bound, if so, get [[BoundFunction]] from it 379 // and use that instead of F. 380 var bindings = %BoundFunctionGetBindings(F); 381 if (bindings) { 382 F = bindings[kBoundFunctionIndex]; // Always a non-bound function. 383 } 384 // Get the prototype of F; if it is not an object, throw an error. 385 var O = F.prototype; 386 if (!IS_SPEC_OBJECT(O)) { 387 throw %MakeTypeError('instanceof_nonobject_proto', [O]); 388 } 389 390 // Return whether or not O is in the prototype chain of V. 391 return %IsInPrototypeChain(O, V) ? 0 : 1; 392 } 393 394 395 // Filter a given key against an object by checking if the object 396 // has a property with the given key; return the key as a string if 397 // it has. Otherwise returns 0 (smi). Used in for-in statements. 398 function FILTER_KEY(key) { 399 var string = %ToString(key); 400 if (%HasProperty(this, string)) return string; 401 return 0; 402 } 403 404 405 function CALL_NON_FUNCTION() { 406 var delegate = %GetFunctionDelegate(this); 407 if (!IS_FUNCTION(delegate)) { 408 throw %MakeTypeError('called_non_callable', [typeof this]); 409 } 410 return %Apply(delegate, this, arguments, 0, %_ArgumentsLength()); 411 } 412 413 414 function CALL_NON_FUNCTION_AS_CONSTRUCTOR() { 415 var delegate = %GetConstructorDelegate(this); 416 if (!IS_FUNCTION(delegate)) { 417 throw %MakeTypeError('called_non_callable', [typeof this]); 418 } 419 return %Apply(delegate, this, arguments, 0, %_ArgumentsLength()); 420 } 421 422 423 function CALL_FUNCTION_PROXY() { 424 var arity = %_ArgumentsLength() - 1; 425 var proxy = %_Arguments(arity); // The proxy comes in as an additional arg. 426 var trap = %GetCallTrap(proxy); 427 return %Apply(trap, this, arguments, 0, arity); 428 } 429 430 431 function CALL_FUNCTION_PROXY_AS_CONSTRUCTOR() { 432 var proxy = this; 433 var trap = %GetConstructTrap(proxy); 434 return %Apply(trap, this, arguments, 0, %_ArgumentsLength()); 435 } 436 437 438 function APPLY_PREPARE(args) { 439 var length; 440 // First check whether length is a positive Smi and args is an 441 // array. This is the fast case. If this fails, we do the slow case 442 // that takes care of more eventualities. 443 if (IS_ARRAY(args)) { 444 length = args.length; 445 if (%_IsSmi(length) && length >= 0 && length < 0x800000 && 446 IS_SPEC_FUNCTION(this)) { 447 return length; 448 } 449 } 450 451 length = (args == null) ? 0 : %ToUint32(args.length); 452 453 // We can handle any number of apply arguments if the stack is 454 // big enough, but sanity check the value to avoid overflow when 455 // multiplying with pointer size. 456 if (length > 0x800000) { 457 throw %MakeRangeError('stack_overflow', []); 458 } 459 460 if (!IS_SPEC_FUNCTION(this)) { 461 throw %MakeTypeError('apply_non_function', 462 [ %ToString(this), typeof this ]); 463 } 464 465 // Make sure the arguments list has the right type. 466 if (args != null && !IS_SPEC_OBJECT(args)) { 467 throw %MakeTypeError('apply_wrong_args', []); 468 } 469 470 // Return the length which is the number of arguments to copy to the 471 // stack. It is guaranteed to be a small integer at this point. 472 return length; 473 } 474 475 476 function APPLY_OVERFLOW(length) { 477 throw %MakeRangeError('stack_overflow', []); 478 } 479 480 481 // Convert the receiver to an object - forward to ToObject. 482 function TO_OBJECT() { 483 return %ToObject(this); 484 } 485 486 487 // Convert the receiver to a number - forward to ToNumber. 488 function TO_NUMBER() { 489 return %ToNumber(this); 490 } 491 492 493 // Convert the receiver to a string - forward to ToString. 494 function TO_STRING() { 495 return %ToString(this); 496 } 497 498 499 /* ------------------------------------- 500 - - - C o n v e r s i o n s - - - 501 ------------------------------------- 502 */ 503 504 // ECMA-262, section 9.1, page 30. Use null/undefined for no hint, 505 // (1) for number hint, and (2) for string hint. 506 function ToPrimitive(x, hint) { 507 // Fast case check. 508 if (IS_STRING(x)) return x; 509 // Normal behavior. 510 if (!IS_SPEC_OBJECT(x)) return x; 511 if (hint == NO_HINT) hint = (IS_DATE(x)) ? STRING_HINT : NUMBER_HINT; 512 return (hint == NUMBER_HINT) ? %DefaultNumber(x) : %DefaultString(x); 513 } 514 515 516 // ECMA-262, section 9.2, page 30 517 function ToBoolean(x) { 518 if (IS_BOOLEAN(x)) return x; 519 if (IS_STRING(x)) return x.length != 0; 520 if (x == null) return false; 521 if (IS_NUMBER(x)) return !((x == 0) || NUMBER_IS_NAN(x)); 522 return true; 523 } 524 525 526 // ECMA-262, section 9.3, page 31. 527 function ToNumber(x) { 528 if (IS_NUMBER(x)) return x; 529 if (IS_STRING(x)) { 530 return %_HasCachedArrayIndex(x) ? %_GetCachedArrayIndex(x) 531 : %StringToNumber(x); 532 } 533 if (IS_BOOLEAN(x)) return x ? 1 : 0; 534 if (IS_UNDEFINED(x)) return $NaN; 535 return (IS_NULL(x)) ? 0 : ToNumber(%DefaultNumber(x)); 536 } 537 538 function NonNumberToNumber(x) { 539 if (IS_STRING(x)) { 540 return %_HasCachedArrayIndex(x) ? %_GetCachedArrayIndex(x) 541 : %StringToNumber(x); 542 } 543 if (IS_BOOLEAN(x)) return x ? 1 : 0; 544 if (IS_UNDEFINED(x)) return $NaN; 545 return (IS_NULL(x)) ? 0 : ToNumber(%DefaultNumber(x)); 546 } 547 548 549 // ECMA-262, section 9.8, page 35. 550 function ToString(x) { 551 if (IS_STRING(x)) return x; 552 if (IS_NUMBER(x)) return %_NumberToString(x); 553 if (IS_BOOLEAN(x)) return x ? 'true' : 'false'; 554 if (IS_UNDEFINED(x)) return 'undefined'; 555 return (IS_NULL(x)) ? 'null' : %ToString(%DefaultString(x)); 556 } 557 558 function NonStringToString(x) { 559 if (IS_NUMBER(x)) return %_NumberToString(x); 560 if (IS_BOOLEAN(x)) return x ? 'true' : 'false'; 561 if (IS_UNDEFINED(x)) return 'undefined'; 562 return (IS_NULL(x)) ? 'null' : %ToString(%DefaultString(x)); 563 } 564 565 566 // ECMA-262, section 9.9, page 36. 567 function ToObject(x) { 568 if (IS_STRING(x)) return new $String(x); 569 if (IS_NUMBER(x)) return new $Number(x); 570 if (IS_BOOLEAN(x)) return new $Boolean(x); 571 if (IS_NULL_OR_UNDEFINED(x) && !IS_UNDETECTABLE(x)) { 572 throw %MakeTypeError('null_to_object', []); 573 } 574 return x; 575 } 576 577 578 // ECMA-262, section 9.4, page 34. 579 function ToInteger(x) { 580 if (%_IsSmi(x)) return x; 581 return %NumberToInteger(ToNumber(x)); 582 } 583 584 585 // ECMA-262, section 9.6, page 34. 586 function ToUint32(x) { 587 if (%_IsSmi(x) && x >= 0) return x; 588 return %NumberToJSUint32(ToNumber(x)); 589 } 590 591 592 // ECMA-262, section 9.5, page 34 593 function ToInt32(x) { 594 if (%_IsSmi(x)) return x; 595 return %NumberToJSInt32(ToNumber(x)); 596 } 597 598 599 // ES5, section 9.12 600 function SameValue(x, y) { 601 if (typeof x != typeof y) return false; 602 if (IS_NUMBER(x)) { 603 if (NUMBER_IS_NAN(x) && NUMBER_IS_NAN(y)) return true; 604 // x is +0 and y is -0 or vice versa. 605 if (x === 0 && y === 0 && (1 / x) != (1 / y)) return false; 606 } 607 return x === y; 608 } 609 610 611 /* --------------------------------- 612 - - - U t i l i t i e s - - - 613 --------------------------------- 614 */ 615 616 // Returns if the given x is a primitive value - not an object or a 617 // function. 618 function IsPrimitive(x) { 619 // Even though the type of null is "object", null is still 620 // considered a primitive value. IS_SPEC_OBJECT handles this correctly 621 // (i.e., it will return false if x is null). 622 return !IS_SPEC_OBJECT(x); 623 } 624 625 626 // ECMA-262, section 8.6.2.6, page 28. 627 function DefaultNumber(x) { 628 var valueOf = x.valueOf; 629 if (IS_SPEC_FUNCTION(valueOf)) { 630 var v = %_CallFunction(x, valueOf); 631 if (%IsPrimitive(v)) return v; 632 } 633 634 var toString = x.toString; 635 if (IS_SPEC_FUNCTION(toString)) { 636 var s = %_CallFunction(x, toString); 637 if (%IsPrimitive(s)) return s; 638 } 639 640 throw %MakeTypeError('cannot_convert_to_primitive', []); 641 } 642 643 644 // ECMA-262, section 8.6.2.6, page 28. 645 function DefaultString(x) { 646 var toString = x.toString; 647 if (IS_SPEC_FUNCTION(toString)) { 648 var s = %_CallFunction(x, toString); 649 if (%IsPrimitive(s)) return s; 650 } 651 652 var valueOf = x.valueOf; 653 if (IS_SPEC_FUNCTION(valueOf)) { 654 var v = %_CallFunction(x, valueOf); 655 if (%IsPrimitive(v)) return v; 656 } 657 658 throw %MakeTypeError('cannot_convert_to_primitive', []); 659 } 660 661 662 // NOTE: Setting the prototype for Array must take place as early as 663 // possible due to code generation for array literals. When 664 // generating code for a array literal a boilerplate array is created 665 // that is cloned when running the code. It is essential that the 666 // boilerplate gets the right prototype. 667 %FunctionSetPrototype($Array, new $Array(0)); 668