64 lines
1.6 KiB
Text
64 lines
1.6 KiB
Text
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' Gambas class file
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'' The PrioSet class is much similar to the PrioQueue, except that
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'' the FIFO principle is missing. While a PrioQueue
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''
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'' 1. divides its elements into priority classes and
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'' 2. within each class enforces the FIFO semantics,
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''
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'' a PrioSet does only the first. In other words: using a PrioSet
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'' will give you high-priority elements first but elements with
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'' equal priority will have no a-priori determined ordering.
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''
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'' To most applications the FIFO semantics are irrelevant and
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'' forgetting about them allows for faster algorithms and less
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'' memory used.
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''
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'' Beware that the term "priority queue" is sometimes used to refer
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'' to what we call "priority set" here.
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Export
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Property Read First As Variant
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Property Read Count As Integer
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Property Read IsEmpty As Boolean
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Private $hHeap As Heap
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Public Sub _new()
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$hHeap = New Heap(gb.Ascent)
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End
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Public Sub Insert(Data As Variant, Prio As Integer)
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Dim hEntry As New _PrioSet_Entry(Data, Prio)
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$hHeap.Insert(hEntry)
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End
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Public Sub Remove() As Variant
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Dim hEntry As _PrioSet_Entry = $hHeap.Remove()
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Return hEntry.Data
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End
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Public Sub Update(Old As Variant, {New} As Variant, Prio As Integer)
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Dim hOld As New _PrioSet_Entry(Old, 0) ' Prio doesn't matter here
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Dim hNew As New _PrioSet_Entry({New}, Prio)
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$hHeap.Update(hOld, hNew)
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End
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Private Function First_Read() As Variant
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Dim hEntry As _PrioSet_Entry = $hHeap.First
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Return hEntry.Data
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End
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Private Function Count_Read() As Integer
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Return $hHeap.Count
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End
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Private Function IsEmpty_Read() As Boolean
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Return $hHeap.IsEmpty
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End
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