방법: LINQ 쿼리와 정규식 결합
업데이트: 2007년 11월
이 예제에서는 Regex 클래스를 사용하여 텍스트 문자열에서 좀 더 복잡한 비교를 위해 정규식을 만드는 방법을 보여 줍니다. LINQ 쿼리를 사용하면 정규식을 사용하여 검색하려는 파일만 정확하게 필터링하고 결과를 구체화하는 작업이 쉬워집니다.
예제
Class LinqRegExVB
Shared Sub Main()
' Root folder to query, along with all subfolders.
' Modify this path as necessary.
Dim startFolder As String = "C:\program files\Microsoft Visual Studio 9.0\"
' 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 (searchTerm.Matches(fileText).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.
string startFolder = @"c:\program files\Microsoft Visual Studio 9.0\";
// 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 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.
var queryMatchingFiles =
from file in fileList
where file.Extension == ".htm"
let fileText = System.IO.File.ReadAllText(file.FullName)
let matches = searchTerm.Matches(fileText)
where searchTerm.Matches(fileText).Count > 0
select new
{
name = file.FullName,
matches = 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.matches)
{
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;
}
}
RegEx 검색에서 반환하는 MatchCollection 개체도 쿼리할 수 있습니다. 이 예제에서는 각 일치하는 항목의 값만 결과에서 생성됩니다. 하지만 LINQ를 사용하여 해당 컬렉션에서 모든 종류의 필터링, 정렬 및 그룹화를 수행할 수도 있습니다. MatchCollection은 제네릭이 아닌 IEnumerable 컬렉션이므로 쿼리에서 범위 변수의 형식을 명시적으로 지정해야 합니다.
코드 컴파일
.NET Framework 버전 3.5를 대상으로 하는 Visual Studio 프로젝트를 만듭니다. 기본적으로 프로젝트에는 System.Core.dll에 대한 참조 및 System.Linq 네임스페이스에 대한 using 지시문(C#) 또는 Imports 문(Visual Basic)이 있습니다. C# 프로젝트에서는 System.IO 네임스페이스에 대한 using 지시문을 추가합니다.
프로젝트에 이 코드를 복사합니다.
F5 키를 눌러 프로그램을 컴파일하고 실행합니다.
아무 키나 눌러 콘솔 창을 닫습니다.