gregmac / TypedRegex

C# Source Generator to make classes from Regular Expressions

TypedRegex

C# Source Generator to make classes from Regular Expressions.

Example

Declare an empty partial class with a Regex attribute:

using TypedRegex;
[Regex(@"^(?<year>\d{4})-(?<month>\d{2})-(?<day>\d{2})" +
       @"T(?<hour>\d{2}):(?<min>\d{2}):(?<sec>\d{2}\.\d{3})Z$")]
public partial class IsoDate { }

The rest of the class is auto-generated as:

public partial class IsoDate {
    public Match RawMatch { get; }
    public string Value { get; }
    public MatchGroup Group0 { get; }
    public MatchGroup Year { get; }
    public MatchGroup Month { get; }
    public MatchGroup Day { get; }
    public MatchGroup Hour { get; }
    public MatchGroup Min { get; }
    public MatchGroup Sec { get; }

    public static bool IsMatch(string input);
    public static IsoDate Match(string input);
    public static bool TryMatch(string input, out IsoDate match);
    public static IEnumerable<IsoDate> Matches(string input);
}

All groups become properties and static methods are added for matching, so now you can easily match and get a typed result:

if (IsoDate.TryMatch("2021-02-03T01:23:45.678Z", out var isoDate))
{
    Console.WriteLine($"IsoDate: year={isoDate.Year} month={isoDate.Month} day={isoDate.Day}");
}

or iterate through a set of matches:

foraech (var isoDate in IsoDate.Matches(input))
{
    Console.WriteLine($"Found date: {input.Year}");
}

API

The source generator fills out your CustomType class with the following static methods:

public static bool IsMatch(string input);
public static CustomType Match(string input);
public static bool TryMatch(string input, out CustomType match)
public static IEnumerable<CustomType> Matches(string input)

There is a property added for each match group in the regular expression, named the same as the group name, or named Group0, Group1, etc for non-named groups. Each of these is a TypedRegex.MatchGroup which is kind of a wrapper around System.Text.RegularExpressions.Capture with some additional features:

• Implicit cast to string
• string Value property is the first match (same as Capture.Value)
• int CaptureCount provides number of captures (eg: if a group is repeated)
• IEnumerable<string> Values property is the string value of each capture