Replace per-subsystem annotation providers with pipeline annotation resolver

This simplifies things and means that subsystem authors have one
centralized place to get annotation values, instead of having to
know which subsytem to use.

Author: mhutch

src/System.CommandLine.Subsystems.Tests/AlternateSubsystems.cs

@@ -30,7 +30,7 @@ public VersionThatUsesHelpData(CliSymbol symbol)
 
             public override void Execute(PipelineResult pipelineResult)
             {
-                TryGetAnnotation(Symbol, HelpAnnotations.Description, out string? description);
+                pipelineResult.Pipeline.Annotations.TryGet(Symbol, HelpAnnotations.Description, out string? description);
                 pipelineResult.ConsoleHack.WriteLine(description);
                 pipelineResult.AlreadyHandled = true;
                 pipelineResult.SetSuccess();
@@ -63,12 +63,12 @@ protected internal override void TearDown(PipelineResult pipelineResult)
             }
         }
 
-        internal class StringDirectiveSubsystem(IAnnotationProvider? annotationProvider = null)
-           : DirectiveSubsystem("other", SubsystemKind.Diagram, annotationProvider)
+        internal class StringDirectiveSubsystem()
+           : DirectiveSubsystem("other", SubsystemKind.Diagram)
         { }
 
-        internal class BooleanDirectiveSubsystem(IAnnotationProvider? annotationProvider = null)
-           : DirectiveSubsystem("diagram", SubsystemKind.Diagram, annotationProvider)
+        internal class BooleanDirectiveSubsystem()
+           : DirectiveSubsystem("diagram", SubsystemKind.Diagram)
         { }
 
     }

src/System.CommandLine.Subsystems/CompletionSubsystem.cs

@@ -17,8 +17,8 @@ namespace System.CommandLine;
 
 public class CompletionSubsystem : CliSubsystem
 {
-    public CompletionSubsystem(IAnnotationProvider? annotationProvider = null)
-        : base(CompletionAnnotations.Prefix, SubsystemKind.Completion, annotationProvider)
+    public CompletionSubsystem()
+        : base(CompletionAnnotations.Prefix, SubsystemKind.Completion)
     { }
 
     // TODO: Figure out trigger for completions

src/System.CommandLine.Subsystems/Directives/DiagramSubsystem.cs

@@ -6,8 +6,8 @@
 
 namespace System.CommandLine.Directives;
 
-public class DiagramSubsystem(IAnnotationProvider? annotationProvider = null)
-    : DirectiveSubsystem("diagram", SubsystemKind.Diagram, annotationProvider)
+public class DiagramSubsystem()
+    : DirectiveSubsystem("diagram", SubsystemKind.Diagram)
 {
     //protected internal override bool GetIsActivated(ParseResult? parseResult)
     //   => parseResult is not null && option is not null && parseResult.GetValue(option);

src/System.CommandLine.Subsystems/Directives/DirectiveSubsystem.cs

@@ -13,8 +13,8 @@ public abstract class DirectiveSubsystem : CliSubsystem
     public string Id { get; }
     public Location? Location { get; private set; }
 
-    public DirectiveSubsystem(string name, SubsystemKind kind, IAnnotationProvider? annotationProvider = null, string? id = null)
-        : base(name, kind, annotationProvider: annotationProvider)
+    public DirectiveSubsystem(string name, SubsystemKind kind, string? id = null)
+        : base(name, kind)
     {
         Id = id ?? name;
     }

src/System.CommandLine.Subsystems/Directives/ResponseSubsystem.cs

@@ -7,7 +7,7 @@
 namespace System.CommandLine.Directives;
 
 public class ResponseSubsystem()
-    : CliSubsystem("Response", SubsystemKind.Response, null)
+    : CliSubsystem("Response", SubsystemKind.Response)
 {
     public bool Enabled { get; set; }
 

src/System.CommandLine.Subsystems/ErrorReportingSubsystem.cs

@@ -15,8 +15,8 @@ namespace System.CommandLine;
 /// </remarks>
 public class ErrorReportingSubsystem : CliSubsystem
 {
-    public ErrorReportingSubsystem(IAnnotationProvider? annotationProvider = null)
-        : base(ErrorReportingAnnotations.Prefix, SubsystemKind.ErrorReporting, annotationProvider)
+    public ErrorReportingSubsystem()
+        : base(ErrorReportingAnnotations.Prefix, SubsystemKind.ErrorReporting)
     { }
 
     protected internal override bool GetIsActivated(ParseResult? parseResult)

src/System.CommandLine.Subsystems/HelpAnnotationExtensions.cs

@@ -40,11 +40,28 @@ public static void SetDescription<TSymbol>(this TSymbol symbol, string descripti
     /// <param name="symbol">The symbol</param>
     /// <returns>The symbol description if any, otherwise <see langword="null"/></returns>
     /// <remarks>
-    /// This is intended to be called by CLI authors. Subsystems should instead call <see cref="HelpSubsystem.TryGetDescription(CliSymbol, out string?)"/>,
-    /// values from the subsystem's <see cref="IAnnotationProvider"/>.
+    /// This is intended to be called by CLI authors. Subsystem authors should instead call
+    /// <see cref="GetDescription{TSymbol}(AnnotationResolver, TSymbol)"/> to get values from
+    /// the pipeline's <see cref="Pipeline.Annotations"/>, which takes dynamic providers into account.
     /// </remarks>
     public static string? GetDescription<TSymbol>(this TSymbol symbol) where TSymbol : CliSymbol
     {
         return symbol.GetAnnotationOrDefault<string>(HelpAnnotations.Description);
     }
+
+    /// <summary>
+    /// Get the help description for the <paramref name="symbol"/> from the <paramref name="resolver"/>,
+    /// which takes dynamic providers into account.
+    /// </summary>
+    /// <typeparam name="TSymbol">The type of the symbol</typeparam>
+    /// <param name="symbol">The symbol</param>
+    /// <returns>The symbol description if any, otherwise <see langword="null"/></returns>
+    /// <remarks>
+    /// This is intended to be called by subsystem authors. CLI authors should instead call
+    /// <see cref="GetDescription{TSymbol}(TSymbol)"/> to get the value associated directly with the symbol.
+    /// </remarks>
+    public static string? GetDescription<TSymbol>(this AnnotationResolver resolver, TSymbol symbol) where TSymbol : CliSymbol
+    {
+        return resolver.GetAnnotationOrDefault<string>(symbol, HelpAnnotations.Description);
+    }
 }

src/System.CommandLine.Subsystems/HelpSubsystem.cs

@@ -15,8 +15,8 @@ namespace System.CommandLine;
 //        var command = new CliCommand("greet")
 //          .With(help.Description, "Greet the user");
 //
-public class HelpSubsystem(IAnnotationProvider? annotationProvider = null)
-    : CliSubsystem(HelpAnnotations.Prefix, SubsystemKind.Help, annotationProvider)
+public class HelpSubsystem()
+    : CliSubsystem(HelpAnnotations.Prefix, SubsystemKind.Help)
 {
     /// <summary>
     /// Gets the help option, which allows the user to customize
@@ -44,7 +44,4 @@ public override void Execute(PipelineResult pipelineResult)
         pipelineResult.ConsoleHack.WriteLine("Help me!");
         pipelineResult.SetSuccess();
     }
-
-    public bool TryGetDescription(CliSymbol symbol, out string? description)
-        => TryGetAnnotation(symbol, HelpAnnotations.Description, out description);
 }

src/System.CommandLine.Subsystems/InvocationSubsystem.cs

@@ -6,6 +6,6 @@
 
 namespace System.CommandLine;
 
-public class InvocationSubsystem(IAnnotationProvider? annotationProvider = null)
-    : CliSubsystem(InvocationAnnotations.Prefix, SubsystemKind.Invocation, annotationProvider)
+public class InvocationSubsystem()
+    : CliSubsystem(InvocationAnnotations.Prefix, SubsystemKind.Invocation)
 {}

src/System.CommandLine.Subsystems/Pipeline.cs

@@ -4,6 +4,7 @@
 using System.CommandLine.Directives;
 using System.CommandLine.Parsing;
 using System.CommandLine.Subsystems;
+using System.CommandLine.Subsystems.Annotations;
 
 namespace System.CommandLine;
 
@@ -17,6 +18,7 @@ public partial class Pipeline
     private readonly PipelinePhase<InvocationSubsystem> invocationPhase = new(SubsystemKind.Invocation);
     private readonly PipelinePhase<ErrorReportingSubsystem> errorReportingPhase = new(SubsystemKind.ErrorReporting);
     private readonly IEnumerable<PipelinePhase> phases;
+    private readonly List<IAnnotationProvider> annotationProviders;
 
     /// <summary>
     /// Creates an instance of the pipeline using standard features.
@@ -34,14 +36,15 @@ public static Pipeline Create(HelpSubsystem? help = null,
                                   VersionSubsystem? version = null,
                                   CompletionSubsystem? completion = null,
                                   DiagramSubsystem? diagram = null,
-                                  ErrorReportingSubsystem? errorReporting = null)
-        => new()
+                                  ErrorReportingSubsystem? errorReporting = null,
+                                  IEnumerable<IAnnotationProvider>? annotationProviders = null)
+        => new(annotationProviders)
         {
             Help = help ?? new HelpSubsystem(),
             Version = version ?? new VersionSubsystem(),
             Completion = completion ?? new CompletionSubsystem(),
             Diagram = diagram ?? new DiagramSubsystem(),
-            ErrorReporting = errorReporting ?? new ErrorReportingSubsystem(),
+            ErrorReporting = errorReporting ?? new ErrorReportingSubsystem()
         };
 
     /// <summary>
@@ -54,7 +57,7 @@ public static Pipeline Create(HelpSubsystem? help = null,
     public static Pipeline CreateEmpty()
         => new();
 
-    private Pipeline()
+    private Pipeline(IEnumerable<IAnnotationProvider>? annotationProviders = null)
     {
         Response = new ResponseSubsystem();
         Invocation = new InvocationSubsystem();
@@ -68,6 +71,11 @@ private Pipeline()
             diagramPhase, completionPhase, helpPhase, versionPhase,
             validationPhase, invocationPhase, errorReportingPhase
         ];
+
+        this.annotationProviders = annotationProviders is not null
+            ? [..annotationProviders]
+            : [];
+        Annotations = new(this.annotationProviders);
     }
 
     /// <summary>
@@ -186,6 +194,21 @@ public ErrorReportingSubsystem? ErrorReporting
     /// </summary>
     public ResponseSubsystem Response { get; }
 
+    /// <summary>
+    /// Gets the annotation resolver
+    /// </summary>
+    public AnnotationResolver Annotations { get; }
+
+    /// <summary>
+    /// Gets the list of annotation providers registered with the pipeline
+    /// </summary>
+    public IReadOnlyList<IAnnotationProvider> AnnotationProviders => annotationProviders;
+
+    /// <summary>
+    /// Adds an annotation provider to the pipeline
+    /// </summary>
+    public void AddAnnotationProvider(IAnnotationProvider annotationProvider) => annotationProviders.Add(annotationProvider);
+
     public ParseResult Parse(CliConfiguration configuration, string rawInput)
         => Parse(configuration, CliParser.SplitCommandLine(rawInput).ToArray());