// 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;

}

}