/Pony

# Sort[A: Seq[B] ref, B: Comparable[B] #read]

[Source]

Implementation of dual-pivot quicksort. It operates in-place on the provided Seq, using a small amount of additional memory. The nature of the element-realation is expressed via the supplied comparator.

(The following is paraphrased from Wikipedia.)

Quicksort is a common implementation of a sort algorithm which can sort items of any type for which a "less-than" relation (formally, a total order) is defined.

On average, the algorithm takes O(n log n) comparisons to sort n items. In the worst case, it makes O(n2) comparisons, though this behavior is rare. Multi-pivot implementations (of which dual-pivot is one) make efficient use of modern processor caches.

## Example program

The following takes an reverse-alphabetical array of Strings ("third", "second", "first"), and sorts it in place alphabetically using the default String Comparator.

It outputs:

first second third

```   use "collections"

actor Main
new create(env:Env) =>
let array = [ "third"; "second"; "first" ]
let sorted_array = Sort[Array[String], String](array)
for e in sorted_array.values() do
env.out.print(e) // prints "first \n second \n third"
end
```

```pony
primitive val Sort[A: Seq[B] ref, B: Comparable[B] #read]
```

## Constructors

### create

[Source]

```new val create()
: Sort[A, B] val^
```

## Public Functions

### apply

[Source]

Sort the given seq.

```fun box apply(
a: A)
: A^
```

• a: A

• A^

### eq

[Source]

```fun box eq(
that: Sort[A, B] val)
: Bool val
```

#### Parameters

• that: Sort[A, B] val

### ne

[Source]

```fun box ne(
that: Sort[A, B] val)
: Bool val
```

#### Parameters

• that: Sort[A, B] val

## Private Functions

### _sort

[Source]

```fun box _sort(
a: A,
lo: ISize val,
hi: ISize val)
: None val ?
```

### _swap

[Source]

```fun box _swap(
a: A,
i: ISize val,
j: ISize val)
: None val ?
```