あれがこうなる。

yield って素敵。orz

Option Explicit On

Option Strict On
Imports System

Imports System.Collections

Imports System.Collections.Generic

Imports System.IO
Namespace SilverBouquet.IO


    Public Class LineEnumerator

        Implements IEnumerator(Of String)


        Private _reader As TextReader
        Private _line As String


        Public ReadOnly Property Current() As String Implements System.Collections.Generic.IEnumerator(Of String).Current

            Get

                Return Me._line

            End Get

        End Property


        Private ReadOnly Property IEnumerator_Current() As Object Implements System.Collections.IEnumerator.Current

            Get

                Return Me._line

            End Get

        End Property


        Public Sub New(ByVal reader As TextReader)
            Me._reader = reader
        End Sub


        Public Function MoveNext() As Boolean Implements System.Collections.IEnumerator.MoveNext
            Me._line = Me._reader.ReadLine
            Return Not Me._line = Nothing
        End Function


        Public Sub Reset() Implements System.Collections.IEnumerator.Reset
            Throw New InvalidOperationException("SilverBouquet.IO.LineEnumerator.Reset() can not be called")
        End Sub


        Private Sub Dispose() Implements IDisposable.Dispose
        End Sub


    End Class




    Friend Class LineEnumerable

        Implements IEnumerable(Of String)


        Private _reader As TextReader


        Public Sub New(ByVal reader As TextReader)
            Me._reader = reader
        End Sub


        Public Function GetEnumerator() As System.Collections.Generic.IEnumerator(Of String) Implements System.Collections.Generic.IEnumerable(Of String).GetEnumerator
            Return New LineEnumerator(Me._reader)
        End Function


        Private Function IEnumerable_GetEnumerator() As System.Collections.IEnumerator Implements System.Collections.IEnumerable.GetEnumerator
            Return New LineEnumerator(Me._reader)
        End Function


    End Class


    Public NotInheritable Class Util


        Private Sub New()
        End Sub


        Public Shared Function ReadLines(ByVal reader As TextReader) As IEnumerable(Of String)
            Return New LineEnumerable(reader)
        End Function


    End Class


End Namespace