Question: Furthering use of Span<T> and ReadOnlySpan<T> with string manipulation.

[electricessence]

I've noticed that the System.Text.RegularExpressions namespace is using Span for some processes.
And was thinking possibly a fundamental change is in order for string?

Operations like .Trim(), or even the .Value of Capture should return a ReadOnlySpan<char> or at least have exposed access like .AsSpan().

Thoughts?

[jkotas]

cc @ViktorHofer

[ViktorHofer]

Right there is room for optimization. There are a few ideas and a few open PRs. One i.e. will go into 3.0 as it's a low risk change and doesn't affect the internals of the existing engine too much: dotnet/corefx#32949.

There is another PR which changes the Interpreter to operate on Span instead which showed promising results but hadn't had time yet to refine it and fine a solution for the compiled side: ViktorHofer/corefx#3. This also contains the .Value change you mentioned.

[electricessence]

I was thinking it possible to write an entire set of extensions around Span<char> like .Split() where but might be totally fine to use some of them completely flexible of value type.

[stephentoub]

Capture has a ValueSpan property in. NET 6, and in .NET 7 we've added span-based IsMatch and Count methods, and #65011 tracks additional span-based API on regex. Thanks.