RegexCompilationInfo.MatchTimeout Property

Definition

Namespace:

System.Text.RegularExpressions

Assembly:

System.Text.RegularExpressions.dll

Source:

RegexCompilationInfo.cs

Gets or sets the regular expression's default time-out interval.

public:
 property TimeSpan MatchTimeout { TimeSpan get(); void set(TimeSpan value); };

public TimeSpan MatchTimeout { get; set; }

member this.MatchTimeout : TimeSpan with get, set

Public Property MatchTimeout As TimeSpan

Property Value

TimeSpan

The default maximum time interval that can elapse in a pattern-matching operation before a RegexMatchTimeoutException is thrown, or InfiniteMatchTimeout if time-outs are disabled.

Examples

The following example defines a single compiled regular expression named DuplicateChars that identifies two or more occurrences of the same character in an input string. The compiled regular expression has a default time-out of 2 seconds. When you execute the example, it creates a class library named RegexLib.dll that contains the compiled regular expression.

using System;
using System.Reflection;
using System.Text.RegularExpressions;

public class Example
{
   public static void Main()
   {
        // Match two or more occurrences of the same character.
        string pattern = @"(\w)\1+";
        
        // Use case-insensitive matching. 
        var rci = new RegexCompilationInfo(pattern, RegexOptions.IgnoreCase,
                                           "DuplicateChars", "CustomRegexes", 
                                           true, TimeSpan.FromSeconds(2));

        // Define an assembly to contain the compiled regular expression.
        var an = new AssemblyName();
        an.Name = "RegexLib";
        RegexCompilationInfo[] rciList = { rci };

        // Compile the regular expression and create the assembly.
        Regex.CompileToAssembly(rciList, an);
   }
}

Imports System.Reflection
Imports System.Text.RegularExpressions

Module Example
   Public Sub Main()
        ' Match two or more occurrences of the same character.
        Dim pattern As String = "(\w)\1+"
        
        ' Use case-insensitive matching. 
        Dim rci As New RegexCompilationInfo(pattern, RegexOptions.IgnoreCase,
                                            "DuplicateChars", "CustomRegexes", 
                                            True, TimeSpan.FromSeconds(2))

        ' Define an assembly to contain the compiled regular expression.
        Dim an As New AssemblyName()
        an.Name = "RegexLib"
        Dim rciList As RegexCompilationInfo() = New RegexCompilationInfo() { rci }

        ' Compile the regular expression and create the assembly.
        Regex.CompileToAssembly(rciList, an)
   End Sub
End Module

The regular expression pattern (\w)\1+ is defined as shown in the following table.

Pattern	Description
(\w)	Match any word character and assign it to the first capturing group.
\1+	Match one or more occurrences of the value of the first captured group.

The following example uses the DuplicatedChars regular expression to identify duplicate characters in a string array. When it calls the DuplicatedChars constructor, it changes the time-out interval to .5 seconds.

using CustomRegexes;
using System;
using System.Text.RegularExpressions;

public class Example
{
   public static void Main()
   {
      var rgx = new DuplicateChars(TimeSpan.FromSeconds(.5));
      
      string[] values = { "Greeeeeat", "seed", "deed", "beam", 
                          "loop", "Aardvark" };
      // Display regex information.
      Console.WriteLine("Regular Expression Pattern: {0}", rgx);
      Console.WriteLine("Regex timeout value: {0} seconds\n", 
                        rgx.MatchTimeout.TotalSeconds);
      
      // Display matching information.
      foreach (var value in values) {
         Match m = rgx.Match(value);
         if (m.Success)
            Console.WriteLine("'{0}' found in '{1}' at positions {2}-{3}",
                              m.Value, value, m.Index, m.Index + m.Length - 1);
         else
            Console.WriteLine("No match found in '{0}'", value);
      }                                                         
   }
}
// The example displays the following output:
//       Regular Expression Pattern: (\w)\1+
//       Regex timeout value: 0.5 seconds
//       
//       //eeeee// found in //Greeeeeat// at positions 2-6
//       //ee// found in //seed// at positions 1-2
//       //ee// found in //deed// at positions 1-2
//       No match found in //beam//
//       //oo// found in //loop// at positions 1-2
//       //Aa// found in //Aardvark// at positions 0-1

Imports CustomRegexes
Imports System.Text.RegularExpressions

Module Example
   Public Sub Main()
      Dim rgx As New DuplicateChars(TimeSpan.FromSeconds(.5))
      
      Dim values() As String = { "Greeeeeat", "seed", "deed", "beam", 
                                 "loop", "Aardvark" }
      ' Display regex information.
      Console.WriteLine("Regular Expression Pattern: {0}", rgx)
      Console.WriteLine("Regex timeout value: {0} seconds", 
                        rgx.MatchTimeout.TotalSeconds)
      Console.WriteLine()
      
      ' Display matching information.
      For Each value In values
         Dim m As Match = rgx.Match(value)
         If m.Success Then
            Console.WriteLine("'{0}' found in '{1}' at positions {2}-{3}",
                              m.Value, value, m.Index, m.Index + m.Length - 1)
         Else
            Console.WriteLine("No match found in '{0}'", value)
         End If   
      Next                                                         
   End Sub
End Module
' The example displays the following output:
'       Regular Expression Pattern: (\w)\1+
'       Regex timeout value: 0.5 seconds
'       
'       'eeeee' found in 'Greeeeeat' at positions 2-6
'       'ee' found in 'seed' at positions 1-2
'       'ee' found in 'deed' at positions 1-2
'       No match found in 'beam'
'       'oo' found in 'loop' at positions 1-2
'       'Aa' found in 'Aardvark' at positions 0-1

Remarks

The MatchTimeout property defines the default time-out interval for the compiled regular expression. This value represents the approximate amount of time that a compiled regular expression will execute a single matching operation before the operation times out and the regular expression engine throws a RegexMatchTimeoutException exception during its next timing check.

Important

We recommend that you always set a default time-out value for a compiled regular expression. Consumers of your regular expression library can override that time-out value by passing a TimeSpan value that represents the new time-out interval to the compiled regular expression's class constructor.

You can assign a default time-out value to a RegexCompilationInfo object in any of the following ways:

• By calling the AppDomain.SetData method and providing the string representation of a TimeSpan value for the "REGEX_DEFAULT_MATCH_TIMEOUT" property.

• By calling the RegexCompilationInfo(String, RegexOptions, String, String, Boolean, TimeSpan) constructor and providing a value for the matchTimeout parameter.

• By setting the value of this property.

To set a reasonable time-out interval, consider the following factors:

• The length and complexity of the regular expression pattern. Longer and more complex regular expressions require more time than shorter and simpler ones.

• The expected machine load. Processing takes more time on systems with high CPU and memory utilization.

See also

• RegexCompilationInfo(String, RegexOptions, String, String, Boolean, TimeSpan)