[API Proposal]: Make RegexRunner.CharInClass public instead of protected

[stephentoub]

Background and motivation

The RegexRunner class is the public extensibility point via which source-generated regexes plug in (and via which the older CompileToAssembly compiled regexes plugged in). RegexRunner has a "CharInClass" method that's used by the customized implementations to check whether a character is in a given character class (stored in a particular string representation of that character class). This method is currently protected. But the source generator emits some helpers that want access to this method, which forces it to create a type derived from RegexRunner just to expose that member:

        internal class Base : RegexRunner
        {
            internal static new bool CharInClass(char ch, string charClass) => RegexRunner.CharInClass(ch, charClass);
        }

We can instead just make the member public.

API Proposal

namespace System.Text.RegularExpressions;

public abstract class RegexRunner
{
-    protected static bool CharInClass(char ch, string charClass);
+    public    static bool CharInClass(char ch, string charClass);
}

API Usage

n/a

Alternative Designs

No response

Risks

No response

[ghost]

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Issue Details

---

Background and motivation

The RegexRunner class is the public extensibility point via which source-generated regexes plug in (and via which the older CompileToAssembly compiled regexes plugged in). RegexRunner has a "CharInClass" method that's used by the customized implementations to check whether a character is in a given character class (stored in a particular string representation of that character class). This method is currently protected. But the source generator emits some helpers that want access to this method, which forces it to create a type derived from RegexRunner just to expose that member:

        internal class Base : RegexRunner
        {
            internal static new bool CharInClass(char ch, string charClass) => RegexRunner.CharInClass(ch, charClass);
        }

We can instead just make the member public.

API Proposal

namespace System.Text.RegularExpressions;

public abstract class RegexRunner
{
-    protected static bool CharInClass(char ch, string charClass);
+    public    static bool CharInClass(char ch, string charClass);
}

API Usage

n/a

Alternative Designs

No response

Risks

No response

Author:	stephentoub
Assignees:	-
Labels:	area-System.Text.RegularExpressions, api-ready-for-review
Milestone:	8.0.0

[bartonjs]

Video

Looks good as proposed, though there was a recommendation to EditorBrowsable-Never the member (or the type, for that matter).

namespace System.Text.RegularExpressions;

public abstract class RegexRunner
{
-    protected static bool CharInClass(char ch, string charClass);
+    public    static bool CharInClass(char ch, string charClass);
}