Cara menggabungkan kueri LINQ dengan ekspresi reguler (Visual Basic)
Contoh ini menunjukkan cara menggunakan kelas Regex untuk membuat regex untuk pencocokan yang lebih kompleks dalam string teks. Kueri LINQ memudahkan untuk memfilter file yang ingin Anda cari dengan regex, dan untuk membentuk hasilnya.
Contoh
Imports System.IO
Imports System.Text.RegularExpressions
Class LinqRegExVB
Shared Sub Main()
' Root folder to query, along with all subfolders.
' Modify this path as necessary so that it accesses your Visual Studio folder.
Dim startFolder As String = "C:\Program Files (x86)\Microsoft Visual Studio 14.0\"
' One of the following paths may be more appropriate on your computer.
'Dim startFolder As String = "C:\Program Files (x86)\Microsoft Visual Studio\2017\"
' Take a snapshot of the file system.
Dim fileList As IEnumerable(Of FileInfo) = GetFiles(startFolder)
' Create a regular expression to find all things "Visual".
Dim searchTerm As New Regex("Visual (Basic|C#|C\+\+|Studio)")
' Search the contents of each .htm file.
' Remove the where clause to find even more matches!
' This query produces a list of files where a match
' was found, and a list of the matches in that file.
' Note: Explicit typing of "Match" in select clause.
' This is required because MatchCollection is not a
' generic IEnumerable collection.
Dim queryMatchingFiles = From afile In fileList
Where afile.Extension = ".htm"
Let fileText = File.ReadAllText(afile.FullName)
Let matches = searchTerm.Matches(fileText)
Where (matches.Count > 0)
Select Name = afile.FullName,
Matches = From match As Match In matches
Select match.Value
' Execute the query.
Console.WriteLine("The term " & searchTerm.ToString() & " was found in:")
For Each fileMatches In queryMatchingFiles
' Trim the path a bit, then write
' the file name in which a match was found.
Dim s = fileMatches.Name.Substring(startFolder.Length - 1)
Console.WriteLine(s)
' For this file, write out all the matching strings
For Each match In fileMatches.Matches
Console.WriteLine(" " + match)
Next
Next
' Keep the console window open in debug mode
Console.WriteLine("Press any key to exit")
Console.ReadKey()
End Sub
' Function to retrieve a list of files. Note that this is a copy
' of the file information.
Shared Function GetFiles(root As String) As IEnumerable(Of FileInfo)
Return From file In My.Computer.FileSystem.GetFiles(
root, FileIO.SearchOption.SearchAllSubDirectories, "*.*")
Select New FileInfo(file)
End Function
End Class
Perhatikan bahwa Anda juga dapat mengkueri objek MatchCollection yang ditampilkan oleh penelusuran Regex. Dalam contoh ini hanya nilai dari setiap kecocokan yang dibuat dalam hasil. Namun, LINQ dapat digunakan untuk melakukan semua jenis pemfilteran, pengurutan, dan pengelompokan pada kumpulan itu. Karena kumpulan MatchCollection bersifat non-generik IEnumerable, Anda harus secara eksplisit menyatakan jenis variabel rentang dalam kueri.
Mengkompilasi kode
Buat proyek aplikasi konsol Visual Basic, salin dan tempel sampel kode, dan sesuaikan nilai objek Startup di properti proyek.
