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LibJS: Implement proposed Array.prototype.findLast{,Index}

Proposal: https://tc39.es/proposal-array-find-from-last/
This commit is contained in:
davidot 2021-08-03 14:12:47 +02:00 committed by Linus Groh
parent 44da58c0b2
commit b6523906b3
5 changed files with 229 additions and 0 deletions

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@ -58,6 +58,8 @@ void ArrayPrototype::initialize(GlobalObject& global_object)
define_native_function(vm.names.includes, includes, 1, attr);
define_native_function(vm.names.find, find, 1, attr);
define_native_function(vm.names.findIndex, find_index, 1, attr);
define_native_function(vm.names.findLast, find_last, 1, attr);
define_native_function(vm.names.findLastIndex, find_last_index, 1, attr);
define_native_function(vm.names.some, some, 1, attr);
define_native_function(vm.names.every, every, 1, attr);
define_native_function(vm.names.splice, splice, 2, attr);
@ -77,12 +79,15 @@ void ArrayPrototype::initialize(GlobalObject& global_object)
define_direct_property(*vm.well_known_symbol_iterator(), get(vm.names.values), attr);
// 23.1.3.34 Array.prototype [ @@unscopables ], https://tc39.es/ecma262/#sec-array.prototype-@@unscopables
// With proposal, https://tc39.es/proposal-array-find-from-last/index.html#sec-array.prototype-@@unscopables
auto* unscopable_list = Object::create(global_object, nullptr);
unscopable_list->create_data_property_or_throw(vm.names.copyWithin, Value(true));
unscopable_list->create_data_property_or_throw(vm.names.entries, Value(true));
unscopable_list->create_data_property_or_throw(vm.names.fill, Value(true));
unscopable_list->create_data_property_or_throw(vm.names.find, Value(true));
unscopable_list->create_data_property_or_throw(vm.names.findIndex, Value(true));
unscopable_list->create_data_property_or_throw(vm.names.findLast, Value(true));
unscopable_list->create_data_property_or_throw(vm.names.findLastIndex, Value(true));
unscopable_list->create_data_property_or_throw(vm.names.flat, Value(true));
unscopable_list->create_data_property_or_throw(vm.names.flatMap, Value(true));
unscopable_list->create_data_property_or_throw(vm.names.includes, Value(true));
@ -1492,6 +1497,104 @@ JS_DEFINE_NATIVE_FUNCTION(ArrayPrototype::find_index)
return Value(-1);
}
// 1 Array.prototype.findLast ( predicate [ , thisArg ] ), https://tc39.es/proposal-array-find-from-last/index.html#sec-array.prototype.findlast
JS_DEFINE_NATIVE_FUNCTION(ArrayPrototype::find_last)
{
auto predicate = vm.argument(0);
auto this_arg = vm.argument(1);
// 1. Let O be ? ToObject(this value).
auto* object = vm.this_value(global_object).to_object(global_object);
if (vm.exception())
return {};
// 2. Let len be ? LengthOfArrayLike(O).
auto length = length_of_array_like(global_object, *object);
if (vm.exception())
return {};
// 3. If IsCallable(predicate) is false, throw a TypeError exception.
if (!predicate.is_function()) {
vm.throw_exception<TypeError>(global_object, ErrorType::NotAFunction, predicate.to_string_without_side_effects());
return {};
}
// 4. Let k be len - 1.
// 5. Repeat, while k ≥ 0,
for (i64 k = length - 1; k >= 0; --k) {
// a. Let Pk be ! ToString(𝔽(k)).
auto property_name = PropertyName { k };
// b. Let kValue be ? Get(O, Pk).
auto k_value = object->get(property_name);
if (vm.exception())
return {};
// c. Let testResult be ! ToBoolean(? Call(predicate, thisArg, « kValue, 𝔽(k), O »)).
auto test_result = vm.call(predicate.as_function(), this_arg, k_value, Value((double)k), object);
if (vm.exception())
return {};
// d. If testResult is true, return kValue.
if (test_result.to_boolean())
return k_value;
// e. Set k to k - 1.
}
// 6. Return undefined.
return js_undefined();
}
// 2 Array.prototype.findLastIndex ( predicate [ , thisArg ] ), https://tc39.es/proposal-array-find-from-last/index.html#sec-array.prototype.findlastindex
JS_DEFINE_NATIVE_FUNCTION(ArrayPrototype::find_last_index)
{
auto predicate = vm.argument(0);
auto this_arg = vm.argument(1);
// 1. Let O be ? ToObject(this value).
auto* object = vm.this_value(global_object).to_object(global_object);
if (vm.exception())
return {};
// 2. Let len be ? LengthOfArrayLike(O).
auto length = length_of_array_like(global_object, *object);
if (vm.exception())
return {};
// 3. If IsCallable(predicate) is false, throw a TypeError exception.
if (!predicate.is_function()) {
vm.throw_exception<TypeError>(global_object, ErrorType::NotAFunction, predicate.to_string_without_side_effects());
return {};
}
// 4. Let k be len - 1.
// 5. Repeat, while k ≥ 0,
for (i64 k = length - 1; k >= 0; --k) {
// a. Let Pk be ! ToString(𝔽(k)).
auto property_name = PropertyName { k };
// b. Let kValue be ? Get(O, Pk).
auto k_value = object->get(property_name);
if (vm.exception())
return {};
// c. Let testResult be ! ToBoolean(? Call(predicate, thisArg, « kValue, 𝔽(k), O »)).
auto test_result = vm.call(predicate.as_function(), this_arg, k_value, Value((double)k), object);
if (vm.exception())
return {};
// d. If testResult is true, return 𝔽(k).
if (test_result.to_boolean())
return Value((double)k);
// e. Set k to k - 1.
}
// 6. Return -1𝔽.
return Value(-1);
}
// 23.1.3.26 Array.prototype.some ( callbackfn [ , thisArg ] ), https://tc39.es/ecma262/#sec-array.prototype.some
JS_DEFINE_NATIVE_FUNCTION(ArrayPrototype::some)
{

View file

@ -41,6 +41,8 @@ private:
JS_DECLARE_NATIVE_FUNCTION(includes);
JS_DECLARE_NATIVE_FUNCTION(find);
JS_DECLARE_NATIVE_FUNCTION(find_index);
JS_DECLARE_NATIVE_FUNCTION(find_last);
JS_DECLARE_NATIVE_FUNCTION(find_last_index);
JS_DECLARE_NATIVE_FUNCTION(some);
JS_DECLARE_NATIVE_FUNCTION(every);
JS_DECLARE_NATIVE_FUNCTION(splice);

View file

@ -146,6 +146,8 @@ namespace JS {
P(filter) \
P(finally) \
P(find) \
P(findLast) \
P(findLastIndex) \
P(findIndex) \
P(fixed) \
P(flags) \