src/builtins/array-flat.tq - v8/v8.git - Git at Google

 // 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;
 }
 }
	// 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;
	}
	}