Regular Expression Activities

This topic applies to Windows Workflow Foundation 4 (WF4).

This sample demonstrates how to create a set of activities that expose the regular expression functionality of the System.Text.RegularExpressions namespace. These custom activities can be used within a workflow application. For more information aboutregular expressions, see N:System.Text.RegularExpressions Namespace.

The following table details the custom activities in this sample.

Activity	Description
IsMatch	Specifies whether the regular expression found a match in the input string.
Matches	Searches an input string for all occurrences of a regular expression and returns all the successful matches.
Replace	Within a specified input string, replaces strings that match a regular expression pattern with a specified replacement string.

IsMatch

The IsMatch custom activity returns true if the Input string property finds a match in the regular expression specified in the Pattern property. The activity derives from CodeActivity and within the Execute method calls the IsMatch method.

The following table describes the properties and return value for the IsMatch custom activity.

Property or Return Value	Description
Pattern (required)	The regular expression to search with.
Input (required)	The input string to search.
RegexOptions	Bitwise OR combination of RegexOptions enumeration values.
Return value	true if the input finds a match in the provided pattern; otherwise false.

The following code example demonstrates how to use the IsMatch custom activity.

new IsMatch
{
    Pattern = new InArgument<string>( @"^-?\d+(\.\d{2})?$"),
    Input = "20.00",
};

Matches

The Matches custom activity searches an input string for all occurrences of a regular expression and returns all the successful matches. The activity derives from CodeActivity and within the Execute method calls the Matches method.

The following table describes the properties and return value for the IsMatch custom activity.

Property or Return Value	Description
Pattern (required)	The regular expression to search with.
Input (required)	The input string to search.
RegexOptions	Bitwise OR combination of RegexOptions enumeration values.
Return Value	A MatchCollection that contains the collection of successful matches.

The following code example demonstrates how to use the Matches custom activity.

new Matches
{
    Pattern = @"\b(?<word>\w+)\s+(\k<word>)\b",
    Input = "The quick brown fox  fox jumped over over the lazy dog dog.",
};

Replace

The Replace custom activity searches an input string and replaces all strings that match a specified regular expression with a string. The activity derives from CodeActivity and within the Execute method calls the Replace method.

The following table describes the properties and return value for the Replace custom activity.

Property or Return Value	Description
Pattern (required)	The regular expression to search with.
Input (required)	The input string to search.
Replacement	The replacement string. If a Replacement is specified, then the MatchEvaluator property is ignored. Either the Replacement or MatchEvaluator property must be set.
MatchEvaluator	A custom method that examines each match and returns either the original matched string or a replacement string. If a Replacement is specified, then the MatchEvaluator property is ignored. Either the Replacement or MatchEvaluator property must be set.
RegexOptions	Bitwise OR combination of RegexOptions enumeration values.
Return Value	A MatchCollection that contains the collection of successful matches.

The following code example demonstrates how to use the Replace custom activity.

// Using the replacement string.
new Replace
{
    Pattern = @"\bWorld\b",
    Input = "Hello World! This is a wonderful World",
    Replacement = "Universe"
};

// Using a match evaluator.
new Replace
{
    Pattern = new InArgument<string>(pattern),
    Input = new InArgument<string>(input),
    MatchEvaluator = new MatchEvaluator(CapText)                
};

To use this sample

1. Using Visual Studio 2010, open the RegexActivities.sln solution file.

2. To build the solution, press CTRL+SHIFT+B.

3. To run the solution, press CTRL+F5.

Note:

The samples may already be installed on your machine. Check for the following (default) directory before continuing. <InstallDrive>:\WF_WCF_Samples If this directory does not exist, go to Windows Communication Foundation (WCF) and Windows Workflow Foundation (WF) Samples for .NET Framework 4 to download all Windows Communication Foundation (WCF) and WF samples. This sample is located in the following directory. <InstallDrive>:\WF_WCF_Samples\WF\Scenario\ActivityLibrary\Regex