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LibJS: Implement Array.prototype.sort()

This commit is contained in:
Xavier Cooney 2020-12-26 22:14:14 +11:00 committed by Andreas Kling
parent a103eae0d4
commit ca0f3db004
4 changed files with 368 additions and 0 deletions

View file

@ -70,6 +70,7 @@ void ArrayPrototype::initialize(GlobalObject& global_object)
define_native_function(vm.names.reduce, reduce, 1, attr);
define_native_function(vm.names.reduceRight, reduce_right, 1, attr);
define_native_function(vm.names.reverse, reverse, 0, attr);
define_native_function(vm.names.sort, sort, 1, attr);
define_native_function(vm.names.lastIndexOf, last_index_of, 1, attr);
define_native_function(vm.names.includes, includes, 1, attr);
define_native_function(vm.names.find, find, 1, attr);
@ -600,6 +601,167 @@ JS_DEFINE_NATIVE_FUNCTION(ArrayPrototype::reverse)
return array;
}
static void array_merge_sort(VM& vm, GlobalObject& global_object, Function* compare_func, MarkedValueList& arr_to_sort)
{
// FIXME: it would probably be better to switch to insertion sort for small arrays for
// better performance
if (arr_to_sort.size() <= 1)
return;
MarkedValueList left(vm.heap());
MarkedValueList right(vm.heap());
left.ensure_capacity(arr_to_sort.size() / 2);
right.ensure_capacity(arr_to_sort.size() / 2 + (arr_to_sort.size() & 1));
for (size_t i = 0; i < arr_to_sort.size(); ++i) {
if (i < arr_to_sort.size() / 2) {
left.append(arr_to_sort[i]);
} else {
right.append(arr_to_sort[i]);
}
}
array_merge_sort(vm, global_object, compare_func, left);
if (vm.exception())
return;
array_merge_sort(vm, global_object, compare_func, right);
if (vm.exception())
return;
arr_to_sort.clear();
size_t left_index = 0, right_index = 0;
while (left_index < left.size() && right_index < right.size()) {
auto x = left[left_index];
auto y = right[right_index];
double comparison_result;
if (x.is_undefined() && y.is_undefined()) {
comparison_result = 0;
} else if (x.is_undefined()) {
comparison_result = 1;
} else if (y.is_undefined()) {
comparison_result = -1;
} else if (compare_func) {
auto call_result = vm.call(*compare_func, js_undefined(), left[left_index], right[right_index]);
if (vm.exception())
return;
if (call_result.is_nan()) {
comparison_result = 0;
} else {
comparison_result = call_result.to_double(global_object);
if (vm.exception())
return;
}
} else {
// FIXME: It would probably be much better to be smarter about this and implement
// the Abstract Relational Comparison in line once iterating over code points, rather
// than calling it twice after creating two primitive strings.
auto x_string = x.to_primitive_string(global_object);
if (vm.exception())
return;
auto y_string = y.to_primitive_string(global_object);
if (vm.exception())
return;
auto x_string_value = Value(x_string);
auto y_string_value = Value(y_string);
// Because they are called with primitive strings, these abstract_relation calls
// should never result in a VM exception.
auto x_lt_y_relation = abstract_relation(global_object, true, x_string_value, y_string_value);
ASSERT(x_lt_y_relation != TriState::Unknown);
auto y_lt_x_relation = abstract_relation(global_object, true, y_string_value, x_string_value);
ASSERT(y_lt_x_relation != TriState::Unknown);
if (x_lt_y_relation == TriState::True) {
comparison_result = -1;
} else if (y_lt_x_relation == TriState::True) {
comparison_result = 1;
} else {
comparison_result = 0;
}
}
if (comparison_result <= 0) {
arr_to_sort.append(left[left_index]);
left_index++;
} else {
arr_to_sort.append(right[right_index]);
right_index++;
}
}
while (left_index < left.size()) {
arr_to_sort.append(left[left_index]);
left_index++;
}
while (right_index < right.size()) {
arr_to_sort.append(right[right_index]);
right_index++;
}
}
JS_DEFINE_NATIVE_FUNCTION(ArrayPrototype::sort)
{
auto* array = vm.this_value(global_object).to_object(global_object);
if (vm.exception())
return {};
auto callback = vm.argument(0);
if (!callback.is_undefined() && !callback.is_function()) {
vm.throw_exception<TypeError>(global_object, ErrorType::NotAFunction, callback.to_string_without_side_effects());
return {};
}
auto original_length = get_length(vm, *array);
if (vm.exception())
return {};
MarkedValueList values_to_sort(vm.heap());
for (size_t i = 0; i < original_length; ++i) {
auto element_val = array->get(i);
if (vm.exception())
return {};
if (!element_val.is_empty())
values_to_sort.append(element_val);
}
// Perform sorting by merge sort. This isn't as efficient compared to quick sort, but
// quicksort can't be used in all cases because the spec requires Array.prototype.sort()
// to be stable. FIXME: when initially scanning through the array, maintain a flag
// for if an unstable sort would be indistinguishable from a stable sort (such as just
// just strings or numbers), and in that case use quick sort instead for better performance.
array_merge_sort(vm, global_object, callback.is_undefined() ? nullptr : &callback.as_function(), values_to_sort);
if (vm.exception())
return {};
for (size_t i = 0; i < values_to_sort.size(); ++i) {
array->put(i, values_to_sort[i]);
if (vm.exception())
return {};
}
// The empty parts of the array are always sorted to the end, regardless of the
// compare function. FIXME: For performance, a similar process could be used
// for undefined, which are sorted to right before the empty values.
for (size_t i = values_to_sort.size(); i < original_length; ++i) {
array->delete_property(i);
if (vm.exception())
return {};
}
return array;
}
JS_DEFINE_NATIVE_FUNCTION(ArrayPrototype::last_index_of)
{
auto* this_object = vm.this_value(global_object).to_object(global_object);

View file

@ -56,6 +56,7 @@ private:
JS_DECLARE_NATIVE_FUNCTION(reduce);
JS_DECLARE_NATIVE_FUNCTION(reduce_right);
JS_DECLARE_NATIVE_FUNCTION(reverse);
JS_DECLARE_NATIVE_FUNCTION(sort);
JS_DECLARE_NATIVE_FUNCTION(last_index_of);
JS_DECLARE_NATIVE_FUNCTION(includes);
JS_DECLARE_NATIVE_FUNCTION(find);

View file

@ -194,6 +194,7 @@ namespace JS {
P(sin) \
P(slice) \
P(some) \
P(sort) \
P(source) \
P(splice) \
P(sqrt) \