Comment : combiner des requêtes LINQ avec des expressions régulières
Cet exemple explique comment utiliser la classe Regex pour créer une expression régulière pour des mises en correspondance complexes dans des chaînes de texte. La requête LINQ facilite le filtrage des fichiers précis que vous souhaitez rechercher avec l'expression régulière et de personnaliser les résultats.
Exemple
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;
}
}
Notez que vous pouvez également interroger l'objet MatchCollection retourné par une recherche RegEx. Dans cet exemple, seule la valeur de chaque correspondance est générée dans les résultats. Toutefois, il est également possible d'utiliser LINQ pour effectuer tous les types de filtrage, de tri et de regroupement sur cette collection. Étant donné que MatchCollection est une collection IEnumerable non générique, vous devez déclarer explicitement le type de la variable de portée dans la requête.
Compilation du code
Créez un projet Visual Studio qui cible .NET Framework version 3.5. Par défaut, le projet possède une référence à System.Core.dll et une directive using (C#) ou une instruction Imports (Visual Basic) pour l'espace de noms System.Linq. Dans les projets C#, ajoutez une directive using pour l'espace de noms System.IO.
Copiez ce code dans votre projet.
Appuyez sur F5 pour compiler et exécuter le programme.
Appuyez sur une touche pour quitter la fenêtre de console.
Voir aussi
Tâches
Procédure : générer du code XML à partir de fichiers CSV