Another thing I ran into, not to miss. Maybe everybody who knows javascript is perfectly aware of it, but a default "comparer" sucks at comparing numbers.
For example,
let x = [1, 2, 100];
x.sort();
console.log('sorted', x);
prints
1
100
2
I am concluding array.sort uses toString for sorting. This was totally unexpected, and I suggest comparer should be made a mandatory argument.
Now, in regard to sort implementation, eh, why does it populate map of arrays instead of say quick sort? Quick look on referencesource
internal abstract class EnumerableSorter<TElement>
{
internal abstract void ComputeKeys(TElement[] elements, int count);
internal abstract int CompareKeys(int index1, int index2);
internal int[] Sort(TElement[] elements, int count) {
ComputeKeys(elements, count);
int[] map = new int[count];
for (int i = 0; i < count; i++) map[i] = i;
QuickSort(map, 0, count - 1);
return map;
}
void QuickSort(int[] map, int left, int right) {
do {
int i = left;
int j = right;
int x = map[i + ((j - i) >> 1)];
do {
while (i < map.Length && CompareKeys(x, map[i]) > 0) i++;
while (j >= 0 && CompareKeys(x, map[j]) < 0) j--;
if (i > j) break;
if (i < j) {
int temp = map[i];
map[i] = map[j];
map[j] = temp;
}
i++;
j--;
} while (i <= j);
if (j - left <= right - i) {
if (left < j) QuickSort(map, left, j);
left = i;
}
else {
if (i < right) QuickSort(map, i, right);
right = j;
}
} while (left < right);
}
}
Hello Alex,
Another thing I ran into, not to miss. Maybe everybody who knows javascript is perfectly aware of it, but a default "comparer" sucks at comparing numbers.
For example, let x = [1, 2, 100]; x.sort(); console.log('sorted', x); prints 1 100 2
I am concluding array.sort uses toString for sorting. This was totally unexpected, and I suggest comparer should be made a mandatory argument.
Now, in regard to sort implementation, eh, why does it populate map of arrays instead of say quick sort? Quick look on referencesource
https://github.com/microsoft/referencesource/blob/master/System.Core/System/Linq/Enumerable.cs