Como: Combinar consultas do LINQ com expressões regulares
Este exemplo mostra como usar o Regex classe para criar uma expressão regular para correspondência mais complexas em cadeias de caracteres de texto. O LINQ consulta facilita para o filtro de exatamente os arquivos que você deseja pesquisar com a expressão regular e a forma os resultados.
Exemplo
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;
}
}
Observação Você também pode consultar a MatchCollection objeto retornado por uma RegEx de pesquisa. Neste exemplo, somente o valor de cada correspondência é produzido nos resultados. No entanto, também é possível usar LINQ para executar todos os tipos de filtragem, classificação e agrupamento na coleção. Porque MatchCollection é não genérico IEnumerable coleção, você deve declarar explicitamente o tipo da variável de intervalo em uma consulta.
Compilando o código
Criar um Visual Studio o projeto que se destina a .NET Framework versão 3.5. Por padrão, o projeto tem uma referência a System.Core.dll e um using diretiva (C#) ou Imports instrução (Visual Basic) para o namespace System. LINQ. No C# projetos, adicione um using a diretiva para o namespace System. IO.
Copie este código em seu projeto.
Pressione F5 para compilar e executar o programa.
Pressione qualquer tecla para sair da janela do console.
Consulte também
Tarefas
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