jonathanpeppers / androidregex

Testing .NET 7 `Regex` on Android

AndroidRegex

Testing .NET 7 Regex on Android.

For details, see: https://devblogs.microsoft.com/dotnet/regular-expression-improvements-in-dotnet-7/

private static readonly Regex s_myCoolRegex = new Regex("abc|def", RegexOptions.Compiled | RegexOptions.IgnoreCase);
...
if (s_myCoolRegex.IsMatch(text)) { ... }

VS the new hotness:

[RegexGenerator("abc|def", RegexOptions.IgnoreCase)]
private static partial Regex MyCoolRegex();
...
if (MyCoolRegex().IsMatch(text)) { ... }

Before (RegexOptions.Compiled)

dotnet-trace output:

Startup time on a Pixel 5 device, average of 10 runs:

Average(ms): 307.9
Std Err(ms): 2.38723456930585
Std Dev(ms): 7.54909854809757

After ([GeneratedRegex])

Note that now the static constructor of MainActivity is now so fast that it does not show up in traces at all anymore.

dotnet-trace output:

Startup time on a Pixel 5 device, average of 10 runs:

Average(ms): 214.4
Std Err(ms): 3.06666666666667
Std Dev(ms): 9.69765149118303

This results in a ~93.5ms savings to startup time.