// Copyright 2023 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
namespace array {
transitioning macro ArrayIsArray_Inline(
implicit context: Context)(element: JSAny): Boolean {
if (Is<JSArray>(element)) {
return True;
} else if (Is<JSProxy>(element)) {
return Cast<Boolean>(runtime::ArrayIsArray(element))
otherwise unreachable;
} else {
return False;
}
}
transitioning macro FlattenIntoArrayFast(
implicit context: Context)(target: JSReceiver, source: JSReceiver,
sourceLength: Number, start: Number, depth: Smi, hasMapper: constexpr bool,
mapfn: JSAny, thisArgs: JSAny): Number
labels Bailout(Number, Number) {
// 1. Let targetIndex be start.
let targetIndex: Number = start;
// 2. Let sourceIndex be 0.
let smiSourceIndex: Smi = 0;
const fastSource = Cast<FastJSArray>(source)
otherwise goto Bailout(targetIndex, smiSourceIndex);
let fastOW = NewFastJSArrayWitness(fastSource);
// The source is a FastJSArray, thus its length must be a Smi.
dcheck(Is<Smi>(sourceLength));
const smiSourceLength = UnsafeCast<Smi>(sourceLength);
// 3. Repeat, while sourceIndex < sourceLen
for (; smiSourceIndex < smiSourceLength; smiSourceIndex++) {
fastOW.Recheck() otherwise goto Bailout(targetIndex, smiSourceIndex);
// Ensure that we haven't walked beyond a possibly updated length.
if (smiSourceIndex >= fastOW.Get().length)
goto Bailout(targetIndex, smiSourceIndex);
// a. Let P be ! ToString(sourceIndex).
// b. Let exists be ? HasProperty(source, P).
// i. Let element be ? Get(source, P).
let element = fastOW.LoadElementNoHole(smiSourceIndex)
otherwise continue;
// ii. If mapperFunction is present, then
if constexpr (hasMapper) {
// 1. Set element to ? Call(mapperFunction, thisArgs , « element,
// sourceIndex, source »).
element = Call(context, mapfn, thisArgs, element, smiSourceIndex, source);
}
// iii. Let shouldFlatten be false.
let shouldFlatten: Boolean = False;
// iv. If depth > 0, then
let elementLength: Number = 0;
if (depth > 0) {
// Set shouldFlatten to ? IsArray(element).
// 1. Let elementLen be ? ToLength(? Get(element, "length")).
try {
const elementJSArray: JSArray =
Cast<JSArray>(element) otherwise NonJSArray;
shouldFlatten = True;
elementLength = elementJSArray.length;
} label NonJSArray {
if (Is<JSProxy>(element)) {
shouldFlatten = Cast<Boolean>(runtime::ArrayIsArray(element))
otherwise unreachable;
}
if (shouldFlatten == True) {
elementLength = GetLengthProperty(element);
}
}
}
// v. If shouldFlatten is true, then
if (shouldFlatten == True) {
if (elementLength > 0) {
// 2. Set targetIndex to ? FlattenIntoArray(target, element,
// elementLen, targetIndex, depth - 1).
const element = Cast<JSReceiver>(element) otherwise unreachable;
targetIndex = FlattenIntoArrayWithoutMapFn(
target, element, elementLength, targetIndex, depth - 1);
}
} else {
// 1. If targetIndex >= 2^53-1, throw a TypeError exception.
if (targetIndex >= kMaxSafeInteger) deferred {
ThrowTypeError(
MessageTemplate::kFlattenPastSafeLength, sourceLength,
targetIndex);
}
// 2. Perform ? CreateDataPropertyOrThrow(target,
// ! ToString(targetIndex),
// element).
FastCreateDataProperty(target, targetIndex, element);
targetIndex++;
}
}
return targetIndex;
}
// https://tc39.github.io/proposal-flatMap/#sec-FlattenIntoArray
transitioning macro FlattenIntoArraySlow(
implicit context: Context)(target: JSReceiver, source: JSReceiver,
sourceIndex: Number, sourceLength: Number, start: Number, depth: Smi,
hasMapper: constexpr bool, mapfn: JSAny, thisArgs: JSAny): Number {
// 1. Let targetIndex be start.
let targetIndex: Number = start;
// 2. Let sourceIndex be 0.
let sourceIndex: Number = sourceIndex;
// 3. Repeat, while sourceIndex < sourceLen
while (sourceIndex < sourceLength) {
// a. Let P be ! ToString(sourceIndex).
// b. Let exists be ? HasProperty(source, P).
const exists: Boolean = HasProperty(source, sourceIndex);
if (exists == True) {
let element: JSAny;
// i. Let element be ? Get(source, P).
element = GetProperty(source, sourceIndex);
// ii. If mapperFunction is present, then
if constexpr (hasMapper) {
// 1. Set element to ? Call(mapperFunction, thisArgs , « element,
// sourceIndex, source »).
element = Call(context, mapfn, thisArgs, element, sourceIndex, source);
}
// iii. Let shouldFlatten be false.
let shouldFlatten: Boolean = False;
// iv. If depth > 0, then
if (depth > 0) {
// Set shouldFlatten to ? IsArray(element).
shouldFlatten = ArrayIsArray_Inline(element);
}
// v. If shouldFlatten is true, then
if (shouldFlatten == True) {
// 1. Let elementLen be ? ToLength(? Get(element, "length")).
const elementLength: Number = GetLengthProperty(element);
// 2. Set targetIndex to ? FlattenIntoArray(target, element,
// elementLen, targetIndex, depth - 1).
const element = Cast<JSReceiver>(element) otherwise unreachable;
targetIndex = FlattenIntoArrayWithoutMapFn(
target, element, elementLength, targetIndex, depth - 1);
} else {
// 1. If targetIndex >= 2^53-1, throw a TypeError exception.
if (targetIndex >= kMaxSafeInteger) deferred {
ThrowTypeError(
MessageTemplate::kFlattenPastSafeLength, sourceLength,
targetIndex);
}
// 2. Perform ? CreateDataPropertyOrThrow(target,
// ! ToString(targetIndex),
// element).
FastCreateDataProperty(target, targetIndex, element);
targetIndex++;
}
}
// d. Increase sourceIndex by 1.
sourceIndex++;
}
return targetIndex;
}
transitioning macro FlattenIntoArray(
implicit context: Context)(target: JSReceiver, source: JSReceiver,
sourceLength: Number, start: Number, depth: Smi, hasMapper: constexpr bool,
mapfn: JSAny, thisArgs: JSAny): Number {
try {
return FlattenIntoArrayFast(
target, source, sourceLength, start, depth, hasMapper, mapfn, thisArgs)
otherwise Bailout;
} label Bailout(kTargetIndex: Number, kSourceIndex: Number) {
return FlattenIntoArraySlow(
target, source, kSourceIndex, sourceLength, kTargetIndex, depth,
hasMapper, mapfn, thisArgs);
}
}
transitioning builtin FlattenIntoArrayWithoutMapFn(
implicit context: Context)(target: JSReceiver, source: JSReceiver,
sourceLength: Number, start: Number, depth: Smi): Number {
// This builtin might get called recursively, check stack for overflow
// manually as it has stub linkage.
PerformStackCheck();
return FlattenIntoArray(
target, source, sourceLength, start, depth, false, Undefined, Undefined);
}
transitioning builtin FlattenIntoArrayWithMapFn(
implicit context: Context)(target: JSReceiver, source: JSReceiver,
sourceLength: Number, start: Number, depth: Smi, mapfn: JSAny,
thisArgs: JSAny): Number {
return FlattenIntoArray(
target, source, sourceLength, start, depth, true, mapfn, thisArgs);
}
// https://tc39.github.io/proposal-flatMap/#sec-Array.prototype.flat
transitioning javascript builtin ArrayPrototypeFlat(
js-implicit context: NativeContext, receiver: JSAny)(...arguments): JSAny {
// 1. Let O be ? ToObject(this value).
const o: JSReceiver = ToObject_Inline(context, receiver);
// 2. Let sourceLen be ? ToLength(? Get(O, "length")).
const len: Number = GetLengthProperty(o);
// 3. Let depthNum be 1.
let depthNum: Number = 1;
// 4. If depth is not Undefined, then
if (arguments[0] != Undefined) {
// a. Set depthNum to ? ToInteger(depth).
depthNum = ToInteger_Inline(arguments[0]);
}
// We will hit stack overflow before the stack depth reaches kSmiMax, so we
// can truncate depthNum(Number) to Smi to improve performance.
let depthSmi: Smi = 0;
try {
depthSmi = Cast<PositiveSmi>(depthNum) otherwise NotPositiveSmi;
} label NotPositiveSmi {
if (depthNum <= 0) {
depthSmi = 0;
} else {
depthSmi = Convert<Smi>(Convert<intptr>(kSmiMax));
}
}
// 5. Let A be ? ArraySpeciesCreate(O, 0).
const a: JSReceiver = ArraySpeciesCreate(context, o, 0);
// 6. Perform ? FlattenIntoArray(A, O, sourceLen, 0, depthNum).
FlattenIntoArrayWithoutMapFn(a, o, len, 0, depthSmi);
// 7. Return A.
return a;
}
// https://tc39.github.io/proposal-flatMap/#sec-Array.prototype.flatMap
transitioning javascript builtin ArrayPrototypeFlatMap(
js-implicit context: NativeContext, receiver: JSAny)(...arguments): JSAny {
// 1. Let O be ? ToObject(this value).
const o: JSReceiver = ToObject_Inline(context, receiver);
// 2. Let sourceLen be ? ToLength(? Get(O, "length")).
const len: Number = GetLengthProperty(o);
// 3. If IsCallable(mapperFunction) is false, throw a TypeError exception.
let mapfn: Callable;
try {
mapfn = Cast<Callable>(arguments[0])
otherwise NonCallableError;
} label NonCallableError deferred {
ThrowCalledNonCallable(arguments[0]);
}
// 4. If thisArgs is present, let T be thisArgs; else let T be Undefined.
const t: JSAny = arguments[1];
// 5. Let A be ? ArraySpeciesCreate(O, 0).
const a: JSReceiver = ArraySpeciesCreate(context, o, 0);
// 6. Perform ? FlattenIntoArray(A, O, sourceLen, 0, depthNum).
FlattenIntoArrayWithMapFn(a, o, len, 0, 1, mapfn, t);
// 7. Return A.
return a;
}
}