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

基本上我想摆脱Scripting.TextStream。

另外，我想逐行阅读文本

Answer 1

您可以使用StreamReader和异步ReadLineAsync方法异步方法将取代“丑陋”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

不相关，但isUnique参数将此方法划分为两个不同的逻辑 - 所以我建议不要使用参数引入两种不同的方法

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

如何最有效地将此代码替换为vb.net版本？

1 个答案: