mirror of
https://github.com/RGBCube/serenity
synced 2025-07-27 03:47:35 +00:00
LibJS: Implement Iterator.prototype.reduce
This commit is contained in:
parent
ad42b4ea67
commit
acc05480e8
3 changed files with 196 additions and 0 deletions
|
@ -35,6 +35,7 @@ ThrowCompletionOr<void> IteratorPrototype::initialize(Realm& realm)
|
|||
define_native_function(realm, vm.names.take, take, 1, attr);
|
||||
define_native_function(realm, vm.names.drop, drop, 1, attr);
|
||||
define_native_function(realm, vm.names.flatMap, flat_map, 1, attr);
|
||||
define_native_function(realm, vm.names.reduce, reduce, 1, attr);
|
||||
|
||||
return {};
|
||||
}
|
||||
|
@ -445,4 +446,74 @@ JS_DEFINE_NATIVE_FUNCTION(IteratorPrototype::flat_map)
|
|||
return result;
|
||||
}
|
||||
|
||||
// 3.1.3.7 Iterator.prototype.reduce ( reducer [ , initialValue ] ), https://tc39.es/proposal-iterator-helpers/#sec-iteratorprototype.reduce
|
||||
JS_DEFINE_NATIVE_FUNCTION(IteratorPrototype::reduce)
|
||||
{
|
||||
auto reducer = vm.argument(0);
|
||||
|
||||
// 1. Let O be the this value.
|
||||
// 2. If O is not an Object, throw a TypeError exception.
|
||||
auto object = TRY(this_object(vm));
|
||||
|
||||
// 3. If IsCallable(reducer) is false, throw a TypeError exception.
|
||||
if (!reducer.is_function())
|
||||
return vm.throw_completion<TypeError>(ErrorType::NotAFunction, "reducer"sv);
|
||||
|
||||
// 4. Let iterated be ? GetIteratorDirect(O).
|
||||
auto iterated = TRY(get_iterator_direct(vm, object));
|
||||
|
||||
Value accumulator;
|
||||
size_t counter = 0;
|
||||
|
||||
// 5. If initialValue is not present, then
|
||||
if (vm.argument_count() < 2) {
|
||||
// a. Let next be ? IteratorStep(iterated).
|
||||
auto next = TRY(iterator_step(vm, iterated));
|
||||
|
||||
// b. If next is false, throw a TypeError exception.
|
||||
if (!next)
|
||||
return vm.throw_completion<TypeError>(ErrorType::ReduceNoInitial);
|
||||
|
||||
// c. Let accumulator be ? IteratorValue(next).
|
||||
accumulator = TRY(iterator_value(vm, *next));
|
||||
|
||||
// d. Let counter be 1.
|
||||
counter = 1;
|
||||
}
|
||||
// 6. Else,
|
||||
else {
|
||||
// a. Let accumulator be initialValue.
|
||||
accumulator = vm.argument(1);
|
||||
|
||||
// b. Let counter be 0.
|
||||
counter = 0;
|
||||
}
|
||||
|
||||
// 7. Repeat,
|
||||
while (true) {
|
||||
// a. Let next be ? IteratorStep(iterated).
|
||||
auto next = TRY(iterator_step(vm, iterated));
|
||||
|
||||
// b. If next is false, return accumulator.
|
||||
if (!next)
|
||||
return accumulator;
|
||||
|
||||
// c. Let value be ? IteratorValue(next).
|
||||
auto value = TRY(iterator_value(vm, *next));
|
||||
|
||||
// d. Let result be Completion(Call(reducer, undefined, « accumulator, value, 𝔽(counter) »)).
|
||||
auto result = call(vm, reducer.as_function(), js_undefined(), accumulator, value, Value { counter });
|
||||
|
||||
// e. IfAbruptCloseIterator(result, iterated).
|
||||
if (result.is_error())
|
||||
return *TRY(iterator_close(vm, iterated, result.release_error()));
|
||||
|
||||
// f. Set accumulator to result.[[Value]].
|
||||
accumulator = result.release_value();
|
||||
|
||||
// g. Set counter to counter + 1.
|
||||
++counter;
|
||||
}
|
||||
}
|
||||
|
||||
}
|
||||
|
|
|
@ -27,6 +27,7 @@ private:
|
|||
JS_DECLARE_NATIVE_FUNCTION(take);
|
||||
JS_DECLARE_NATIVE_FUNCTION(drop);
|
||||
JS_DECLARE_NATIVE_FUNCTION(flat_map);
|
||||
JS_DECLARE_NATIVE_FUNCTION(reduce);
|
||||
};
|
||||
|
||||
}
|
||||
|
|
|
@ -0,0 +1,124 @@
|
|||
describe("errors", () => {
|
||||
test("called with non-callable object", () => {
|
||||
expect(() => {
|
||||
Iterator.prototype.reduce(Symbol.hasInstance);
|
||||
}).toThrowWithMessage(TypeError, "reducer is not a function");
|
||||
});
|
||||
|
||||
test("iterator's next method throws", () => {
|
||||
function TestError() {}
|
||||
|
||||
class TestIterator extends Iterator {
|
||||
next() {
|
||||
throw new TestError();
|
||||
}
|
||||
}
|
||||
|
||||
expect(() => {
|
||||
new TestIterator().reduce(() => 0);
|
||||
}).toThrow(TestError);
|
||||
});
|
||||
|
||||
test("value returned by iterator's next method throws", () => {
|
||||
function TestError() {}
|
||||
|
||||
class TestIterator extends Iterator {
|
||||
next() {
|
||||
return {
|
||||
done: false,
|
||||
get value() {
|
||||
throw new TestError();
|
||||
},
|
||||
};
|
||||
}
|
||||
}
|
||||
|
||||
expect(() => {
|
||||
new TestIterator().reduce(() => 0);
|
||||
}).toThrow(TestError);
|
||||
});
|
||||
|
||||
test("reducer function throws", () => {
|
||||
function TestError() {}
|
||||
|
||||
class TestIterator extends Iterator {
|
||||
next() {
|
||||
return {
|
||||
done: false,
|
||||
value: 1,
|
||||
};
|
||||
}
|
||||
}
|
||||
|
||||
expect(() => {
|
||||
new TestIterator().reduce(() => {
|
||||
throw new TestError();
|
||||
});
|
||||
}).toThrow(TestError);
|
||||
});
|
||||
|
||||
test("no available initial value", () => {
|
||||
function* generator() {}
|
||||
|
||||
expect(() => {
|
||||
generator().reduce(() => 0);
|
||||
}).toThrowWithMessage(TypeError, "Reduce of empty array with no initial value");
|
||||
});
|
||||
});
|
||||
|
||||
describe("normal behavior", () => {
|
||||
test("length is 1", () => {
|
||||
expect(Iterator.prototype.reduce).toHaveLength(1);
|
||||
});
|
||||
|
||||
test("reducer function sees every value", () => {
|
||||
function* generator() {
|
||||
yield "a";
|
||||
yield "b";
|
||||
}
|
||||
|
||||
let count = 0;
|
||||
|
||||
generator().reduce((accumulator, value, index) => {
|
||||
++count;
|
||||
|
||||
switch (index) {
|
||||
case 0:
|
||||
expect(value).toBe("a");
|
||||
break;
|
||||
case 1:
|
||||
expect(value).toBe("b");
|
||||
break;
|
||||
default:
|
||||
expect().fail(`Unexpected reducer invocation: value=${value} index=${index}`);
|
||||
break;
|
||||
}
|
||||
|
||||
return value;
|
||||
}, "");
|
||||
|
||||
expect(count).toBe(2);
|
||||
});
|
||||
|
||||
test("reducer uses first value as initial value", () => {
|
||||
function* generator() {
|
||||
yield 1;
|
||||
yield 2;
|
||||
yield 3;
|
||||
}
|
||||
|
||||
const result = generator().reduce((accumulator, value) => accumulator + value);
|
||||
expect(result).toBe(6);
|
||||
});
|
||||
|
||||
test("reducer uses provided value as initial value", () => {
|
||||
function* generator() {
|
||||
yield 1;
|
||||
yield 2;
|
||||
yield 3;
|
||||
}
|
||||
|
||||
const result = generator().reduce((accumulator, value) => accumulator + value, 10);
|
||||
expect(result).toBe(16);
|
||||
});
|
||||
});
|
Loading…
Add table
Add a link
Reference in a new issue