feat: update InterfaceStubGenerator to be an incremental generator

InterfaceStubGenerator.Shared/ImmutableEquatableArray.cs

@@ -0,0 +1,93 @@
+using System.Collections;
+
+namespace Refit.Generator;
+
+internal static class ImmutableEquatableArray
+{
+    public static ImmutableEquatableArray<T> Empty<T>()
+        where T : IEquatable<T> => ImmutableEquatableArray<T>.Empty;
+
+    public static ImmutableEquatableArray<T> ToImmutableEquatableArray<T>(
+        this IEnumerable<T>? values
+    )
+        where T : IEquatable<T> => values == null ? Empty<T>() : new(values);
+}
+
+/// <summary>
+/// Provides an immutable list implementation which implements sequence equality.
+/// </summary>
+internal sealed class ImmutableEquatableArray<T>
+    : IEquatable<ImmutableEquatableArray<T>>,
+        IReadOnlyList<T>
+    where T : IEquatable<T>
+{
+    public static ImmutableEquatableArray<T> Empty { get; } = new(Array.Empty<T>());
+
+    private readonly T[] _values;
+    public T this[int index] => _values[index];
+    public int Count => _values.Length;
+
+    public ImmutableEquatableArray(T[] values) => _values = values;
+
+    public ImmutableEquatableArray(IEnumerable<T> values) => _values = values.ToArray();
+
+    public T[] AsArray() => _values;
+
+    public bool Equals(ImmutableEquatableArray<T>? other) =>
+        other != null && ((ReadOnlySpan<T>)_values).SequenceEqual(other._values);
+
+    public override bool Equals(object? obj) =>
+        obj is ImmutableEquatableArray<T> other && Equals(other);
+
+    public override int GetHashCode()
+    {
+        var hash = 0;
+        foreach (T value in _values)
+        {
+            hash = Combine(hash, value.GetHashCode());
+        }
+
+        static int Combine(int h1, int h2)
+        {
+            // RyuJIT optimizes this to use the ROL instruction
+            // Related GitHub pull request: https://github.com/dotnet/coreclr/pull/1830
+            uint rol5 = ((uint)h1 << 5) | ((uint)h1 >> 27);
+            return ((int)rol5 + h1) ^ h2;
+        }
+
+        return hash;
+    }
+
+    public Enumerator GetEnumerator() => new(_values);
+
+    IEnumerator<T> IEnumerable<T>.GetEnumerator() => ((IEnumerable<T>)_values).GetEnumerator();
+
+    IEnumerator IEnumerable.GetEnumerator() => _values.GetEnumerator();
+
+    public struct Enumerator
+    {
+        private readonly T[] _values;
+        private int _index;
+
+        internal Enumerator(T[] values)
+        {
+            _values = values;
+            _index = -1;
+        }
+
+        public bool MoveNext()
+        {
+            var newIndex = _index + 1;
+
+            if ((uint)newIndex < (uint)_values.Length)
+            {
+                _index = newIndex;
+                return true;
+            }
+
+            return false;
+        }
+
+        public readonly T Current => _values[_index];
+    }
+}

InterfaceStubGenerator.Shared/IncrementalValuesProviderExtensions.cs

@@ -0,0 +1,68 @@
+#if ROSLYN_4
+using System.Text;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.Text;
+
+namespace Refit.Generator;
+
+internal static class IncrementalValuesProviderExtensions
+{
+    /// <summary>
+    /// Registers an output node into an <see cref="IncrementalGeneratorInitializationContext"/> to output a diagnostic.
+    /// </summary>
+    /// <param name="context">The input <see cref="IncrementalGeneratorInitializationContext"/> instance.</param>
+    /// <param name="diagnostic">The input <see cref="IncrementalValuesProvider{TValues}"/> sequence of diagnostics.</param>
+    public static void ReportDiagnostics(
+        this IncrementalGeneratorInitializationContext context,
+        IncrementalValuesProvider<Diagnostic> diagnostic
+    )
+    {
+        context.RegisterSourceOutput(
+            diagnostic,
+            static (context, diagnostic) => context.ReportDiagnostic(diagnostic)
+        );
+    }
+
+    /// <summary>
+    /// Registers an output node into an <see cref="IncrementalGeneratorInitializationContext"/> to output diagnostics.
+    /// </summary>
+    /// <param name="context">The input <see cref="IncrementalGeneratorInitializationContext"/> instance.</param>
+    /// <param name="diagnostics">The input <see cref="IncrementalValuesProvider{TValues}"/> sequence of diagnostics.</param>
+    public static void ReportDiagnostics(
+        this IncrementalGeneratorInitializationContext context,
+        IncrementalValueProvider<ImmutableEquatableArray<Diagnostic>> diagnostics
+    )
+    {
+        context.RegisterSourceOutput(
+            diagnostics,
+            static (context, diagnostics) =>
+            {
+                foreach (var diagnostic in diagnostics)
+                {
+                    context.ReportDiagnostic(diagnostic);
+                }
+            }
+        );
+    }
+
+    /// <summary>
+    /// Registers an implementation source output for the provided mappers.
+    /// </summary>
+    /// <param name="context">The context, on which the output is registered.</param>
+    /// <param name="model">The interfaces stubs.</param>
+    public static void EmitSource(
+        this IncrementalGeneratorInitializationContext context,
+        IncrementalValuesProvider<InterfaceModel> model
+    )
+    {
+        context.RegisterImplementationSourceOutput(
+            model,
+            static (spc, model) =>
+            {
+                var mapperText = Emitter.EmitInterface(model);
+                spc.AddSource(model.FileName, SourceText.From(mapperText, Encoding.UTF8));
+            }
+        );
+    }
+}
+#endif

InterfaceStubGenerator.Shared/InterfaceStubGenerator.Shared.projitems

@@ -10,7 +10,17 @@
   </PropertyGroup>
   <ItemGroup>
     <Compile Include="$(MSBuildThisFileDirectory)DiagnosticDescriptors.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Emitter.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)ImmutableEquatableArray.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)IncrementalValuesProviderExtensions.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)InterfaceStubGenerator.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)IsExternalInit.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)ITypeSymbolExtensions.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Models\ContextGenerationModel.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Models\InterfaceModel.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Models\MethodModel.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Models\ParameterModel.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Models\TypeConstraint.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Parser.cs" />
   </ItemGroup>
 </Project>