Jak: łączenie kwerend LINQ z wyrażeń regularnych
W tym przykładzie przedstawiono sposób użycia Regex klasy do tworzenia wyrażenia regularnego do dopasowywania bardziej złożonych w ciągi tekstowe.LINQ Kwerendy ułatwia filtr, na które chcesz przeszukać z wyrażenia regularnego i kształtu wyniki pliki.
Przykład
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\Microsoft Visual Studio 9.0\"
' One of the following paths may be more appropriate on your computer.
'string startFolder = @"c:\program files (x86)\Microsoft Visual Studio 9.0\";
'string startFolder = @"c:\program files\Microsoft Visual Studio 10.0\";
'string startFolder = @"c:\program files (x86)\Microsoft Visual Studio 10.0\";
' Take a snapshot of the file system.
Dim fileList As IEnumerable(Of System.IO.FileInfo) = GetFiles(startFolder)
' Create a regular expression to find all things "Visual".
Dim searchTerm As System.Text.RegularExpressions.Regex =
New System.Text.RegularExpressions.Regex("Visual (Basic|C#|C\+\+|J#|SourceSafe|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 = System.IO.File.ReadAllText(afile.FullName)
Let matches = searchTerm.Matches(fileText)
Where (matches.Count > 0)
Select Name = afile.FullName,
Matches = From match As System.Text.RegularExpressions.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(ByVal root As String) As IEnumerable(Of System.IO.FileInfo)
Return From file In My.Computer.FileSystem.GetFiles(
root, FileIO.SearchOption.SearchAllSubDirectories, "*.*")
Select New System.IO.FileInfo(file)
End Function
End Class
class QueryWithRegEx
{
public static void Main()
{
// Modify this path as necessary so that it accesses your version of Visual Studio.
string startFolder = @"c:\program files\Microsoft Visual Studio 9.0\";
// One of the following paths may be more appropriate on your computer.
//string startFolder = @"c:\program files (x86)\Microsoft Visual Studio 9.0\";
//string startFolder = @"c:\program files\Microsoft Visual Studio 10.0\";
//string startFolder = @"c:\program files (x86)\Microsoft Visual Studio 10.0\";
// Take a snapshot of the file system.
IEnumerable<System.IO.FileInfo> fileList = GetFiles(startFolder);
// Create the regular expression to find all things "Visual".
System.Text.RegularExpressions.Regex searchTerm =
new System.Text.RegularExpressions.Regex(@"Visual (Basic|C#|C\+\+|J#|SourceSafe|Studio)");
// Search the contents of each .htm file.
// Remove the where clause to find even more matchedValues!
// This query produces a list of files where a match
// was found, and a list of the matchedValues in that file.
// Note: Explicit typing of "Match" in select clause.
// This is required because MatchCollection is not a
// generic IEnumerable collection.
var queryMatchingFiles =
from file in fileList
where file.Extension == ".htm"
let fileText = System.IO.File.ReadAllText(file.FullName)
let matches = searchTerm.Matches(fileText)
where matches.Count > 0
select new
{
name = file.FullName,
matchedValues = from System.Text.RegularExpressions.Match match in matches
select match.Value
};
// Execute the query.
Console.WriteLine("The term \"{0}\" was found in:", searchTerm.ToString());
foreach (var v in queryMatchingFiles)
{
// Trim the path a bit, then write
// the file name in which a match was found.
string s = v.name.Substring(startFolder.Length - 1);
Console.WriteLine(s);
// For this file, write out all the matching strings
foreach (var v2 in v.matchedValues)
{
Console.WriteLine(" " + v2);
}
}
// Keep the console window open in debug mode
Console.WriteLine("Press any key to exit");
Console.ReadKey();
}
// This method assumes that the application has discovery
// permissions for all folders under the specified path.
static IEnumerable<System.IO.FileInfo> GetFiles(string path)
{
if (!System.IO.Directory.Exists(path))
throw new System.IO.DirectoryNotFoundException();
string[] fileNames = null;
List<System.IO.FileInfo> files = new List<System.IO.FileInfo>();
fileNames = System.IO.Directory.GetFiles(path, "*.*", System.IO.SearchOption.AllDirectories);
foreach (string name in fileNames)
{
files.Add(new System.IO.FileInfo(name));
}
return files;
}
}
Należy zauważyć, że można również wysyłać kwerendy MatchCollection obiekt, który jest zwracany przez RegEx wyszukiwania.W tym przykładzie wartość każdego dopasowanie jest produkowany w wynikach.Jednakże, również jest możliwe wykorzystanie LINQ do wykonywania wszelkiego rodzaju filtrowanie, sortowanie i grupowanie w tej kolekcji.Ponieważ MatchCollection jest nie uniwersalne IEnumerable kolekcji, trzeba jawnie podany typ zmiennej zakres w kwerendzie.
Kompilowanie kodu
Tworzenie Visual Studio projekt, który jest przeznaczony dla .NET Framework w wersji 3.5.Domyślnie projekt zawiera odwołanie do System.Core.dll i using dyrektywy (C#) lub Imports instrukcji (Visual Basic) dla obszaru nazw System.Linq.W języku C# projektów, należy dodać using dyrektywa obszaru nazw System.IO.
Skopiuj ten kod do projektu.
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