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// Copyright 2021 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 {
// https://tc39.es/proposal-array-find-from-last/index.html#sec-array.prototype.findlastindex
transitioning builtin ArrayFindLastIndexLoopContinuation(
implicit context: Context)(
predicate: Callable, thisArg: JSAny, o: JSReceiver,
initialK: Number): Number {
// 5. Repeat, while k >= 0
for (let k: Number = initialK; k >= 0; k--) {
// 5a. Let Pk be ! ToString(𝔽(k)).
// k is guaranteed to be a positive integer, hence ToString is
// side-effect free and HasProperty/GetProperty do the conversion inline.
// 5b. Let kValue be ? Get(O, Pk).
const value: JSAny = GetProperty(o, k);
// 5c. Let testResult be ! ToBoolean(? Call(predicate, thisArg, « kValue,
// 𝔽(k), O »)).
const testResult: JSAny = Call(context, predicate, thisArg, value, k, o);
// 5d. If testResult is true, return 𝔽(k).
if (ToBoolean(testResult)) {
return k;
}
// 5e. Set k to k - 1. (done by the loop).
}
// 6. Return -1𝔽.
return Convert<Smi>(-1);
}
// https://tc39.es/proposal-array-find-from-last/index.html#sec-array.prototype.findlastindex
transitioning macro FastArrayFindLastIndex(implicit context: Context)(
o: JSReceiver, len: Number, predicate: Callable, thisArg: JSAny): Number
labels Bailout(Number) {
const smiLen = Cast<Smi>(len) otherwise goto Bailout(len - 1);
// 4. Let k be len - 1.
let k: Smi = smiLen - 1;
const fastO = Cast<FastJSArray>(o) otherwise goto Bailout(k);
let fastOW = NewFastJSArrayWitness(fastO);
// 5. Repeat, while k ≥ 0
// Build a fast loop over the smi array.
for (; k >= 0; k--) {
fastOW.Recheck() otherwise goto Bailout(k);
// Ensure that we haven't walked beyond a possibly updated length.
if (k >= fastOW.Get().length) goto Bailout(k);
// 5a. Let Pk be ! ToString(𝔽(k)).
// k is guaranteed to be a positive integer, hence there is no need to
// cast ToString for LoadElementOrUndefined.
// 5b. Let kValue be ? Get(O, Pk).
const value: JSAny = fastOW.LoadElementOrUndefined(k);
// 5c. Let testResult be ! ToBoolean(? Call(predicate, thisArg, « kValue,
// 𝔽(k), O »)).
const testResult: JSAny =
Call(context, predicate, thisArg, value, k, fastOW.Get());
// 5d. If testResult is true, return 𝔽(k).
if (ToBoolean(testResult)) {
return k;
}
// 5e. Set k to k - 1. (done by the loop).
}
// 6. Return -1𝔽.
return -1;
}
// https://tc39.es/proposal-array-find-from-last/index.html#sec-array.prototype.findlastindex
transitioning javascript builtin
ArrayPrototypeFindLastIndex(
js-implicit context: NativeContext, receiver: JSAny)(...arguments): JSAny {
try {
RequireObjectCoercible(receiver, 'Array.prototype.findLastIndex');
// 1. Let O be ? ToObject(this value).
const o: JSReceiver = ToObject_Inline(context, receiver);
// 2. Let len be ? LengthOfArrayLike(O).
const len: Number = GetLengthProperty(o);
// 3. If IsCallable(predicate) is false, throw a TypeError exception.
if (arguments.length == 0) {
goto NotCallableError;
}
const predicate = Cast<Callable>(arguments[0]) otherwise NotCallableError;
// If a thisArg parameter is provided, it will be used as the this value for
// each invocation of predicate. If it is not provided, undefined is used
// instead.
const thisArg: JSAny = arguments[1];
// Special cases.
try {
return FastArrayFindLastIndex(o, len, predicate, thisArg)
otherwise Bailout;
} label Bailout(k: Number) deferred {
return ArrayFindLastIndexLoopContinuation(predicate, thisArg, o, k);
}
} label NotCallableError deferred {
ThrowTypeError(MessageTemplate::kCalledNonCallable, arguments[0]);
}
}
}
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