Как наиболее эффективно заменить этот код на версию vb.net?

Question

Public Function fileToColHarvest(ByRef stream As Scripting.TextStream, Optional ByRef limit As Integer = 2000000, Optional ByRef unique As Boolean = False, Optional ByRef FirstSectionAsKey As Boolean = False, Optional ByRef prob As Double = 1) As Generic.List(Of String) 
    Dim buffer As String 
    Dim i As Integer 

    If prob < 1 Then 
    End If 
    fileToColHarvest = New Generic.List(Of String) 
    Do While (Not (stream.AtEndOfStream)) 
     i = i + 1 
     System.Windows.Forms.Application.DoEvents() 

     'If Microsoft.VisualBasic.Rnd < 0.01 Then 
     ' appendToTextFile CStr(fileToColHarvest.Count) + "|" + microsoft.visualbasic.str(i) + "|" + buffer, RESULT, ForWriting 
     'End If 
     buffer = stream.ReadLine 
     'buffer = Microsoft.VisualBasic.Replace(buffer, " ", "+") 
     If Microsoft.VisualBasic.Rnd() < prob Then 
      If unique Then 
       If Not FirstSectionAsKey Then 
        fileToColHarvest.AddIfNotExist(buffer) 
       Else 
        fileToColHarvest.AddIfNotExist(buffer) 
       End If 
      Else 
       fileToColHarvest.Add(buffer) 
      End If 
     End If 
     If fileToColHarvest.Count() >= limit Then 
      Exit Do 
     End If 
    Loop 
End Function 

В принципе, я хочу избавиться от Scripting.TextStream.

Кроме того, я хочу, чтобы прочитать текст построчно

Answer 1

Вы можете использовать StreamReader и асинхронный ReadLineAsync метод.
Асинхронный подход заменит «некрасиво» Application.DoEvents()

Public Async Function FileToColHarvest(
    pathToFile As String, 
    limit As Integer, 
    isUnique As Boolean, 
    isFirstSectionAsKey As Boolean, 
    prob As Single) As Task(Of List(Of String)) 

    Dim lines = New List(Of String)() 
    Dim uniqueLines = New HashSet(Of String)() 

    Using stream As New FileStream(pathToFile, FileMode.Open) 
     Using reader As New StreamReader(stream) 
      While reader.EndOfStream = False 
       'Await will prevent blocking UI thread 
       var line = Await reader.ReadLineAsync() 

       If prob < VBMath.Rnd() Then Continue While 

       ' I have removed check of isFirstSectionAsKey 
       ' because based on your code it does same thing 
       If isUnique Then 
        uniqueLines.Add(line) 
        If uniqueLines.Count >= limit Then Return uniqueLines.ToList() 
       Else 
        lines.Add(line) 
        If lines.Count >= limit Then Return lines 
       End If 
      End While    
     End Using 
    End Using 

    Return If(isUnique, uniqueLines.ToList(), lines) 
End Function 

не связаны, но isUnique аргумент делят этот метод в двух различных логики - так что я предлагаю вместо параметра ввести два различных метода

FileToColHarvest(...) 
FileToColHarvestWithUniqueOnly(...)