--- /dev/null
+module ParasitemiaCore.Heap
+
+open System.Collections.Generic
+
+let inline private parent (i: int) : int = (i - 1) / 2
+let inline private left (i: int) : int = 2 * (i + 1) - 1
+let inline private right (i: int) : int = 2 * (i + 1)
+
+[<Struct>]
+type private Node<'k, 'v> =
+ val mutable key: 'k
+ val value: 'v
+ new (k, v) = { key = k; value = v }
+ override this.ToString () = sprintf "%A -> %A" this.key this.value
+
+type Heap<'k, 'v> (kComparer : IComparer<'k>) =
+ let a = List<Node<'k, 'v>>()
+
+ let rec heapUp (i: int) =
+ let l, r = left i, right i
+
+ // Is the left child greater than the parent?
+ let mutable max = if l < a.Count && kComparer.Compare(a.[l].key, a.[i].key) > 0 then l else i
+
+ // Is the right child greater than the parent and the left child?
+ if r < a.Count && kComparer.Compare(a.[r].key, a.[max].key) > 0
+ then
+ max <- r
+
+ // If a child is greater than the parent.
+ if max <> i
+ then
+ let tmp = a.[i]
+ a.[i] <- a.[max]
+ a.[max] <- tmp
+ heapUp max
+
+ // Check the integrity of the heap, use for debug only.
+ let rec checkIntegrity (i: int) : bool =
+ let l, r = left i, right i
+ let leftIntegrity =
+ if l < a.Count
+ then
+ if kComparer.Compare(a.[l].key, a.[i].key) > 0
+ then false
+ else checkIntegrity l
+ else
+ true
+ let rightIntegrity =
+ if r < a.Count
+ then
+ if kComparer.Compare(a.[r].key, a.[i].key) > 0
+ then false
+ else checkIntegrity r
+ else
+ true
+ leftIntegrity && rightIntegrity
+
+ interface IEnumerable<'k * 'v> with
+ member this.GetEnumerator () : IEnumerator<'k * 'v> =
+ (seq { for e in a -> e.key, e.value }).GetEnumerator()
+
+ interface System.Collections.IEnumerable with
+ member this.GetEnumerator () : System.Collections.IEnumerator =
+ (this :> IEnumerable<'k * 'v>).GetEnumerator() :> System.Collections.IEnumerator
+
+ member this.Next () : 'k * 'v =
+ let node = a.[0]
+ a.[0] <- a.[a.Count - 1]
+ a.RemoveAt(a.Count - 1)
+ heapUp 0
+ node.key, node.value
+
+ member this.RemoveNext () =
+ a.[0] <- a.[a.Count - 1]
+ a.RemoveAt(a.Count - 1)
+ heapUp 0
+
+ member this.Add (key: 'k) (value: 'v) =
+ a.Add(Node(key, value))
+
+ let mutable i = a.Count - 1
+ while i > 0 && kComparer.Compare(a.[parent i].key, a.[i].key) < 0 do
+ let tmp = a.[parent i]
+ a.[parent i] <- a.[i]
+ a.[i] <- tmp
+ i <- parent i
+
+ member this.IsEmpty = a.Count = 0
+ member this.Count = a.Count
+
+ member this.Max : 'k * 'v =
+ let max = a.[0]
+ max.key, max.value
+
+ member this.Clear () = a.Clear()
+
+