Implement FixedArrayGenerator

2026-07-15 14:19:29 +00:00 · 2025-05-17 17:50:29 +02:00
parent 818240fcea
commit bae28b2552
2 changed files with 144 additions and 2 deletions
@@ -0,0 +1,142 @@
+using Microsoft.CodeAnalysis;
+using Sybil;
+using System.Text;
+using System.Linq;
+
+namespace System.Extensions;
+#nullable enable
+[Generator(LanguageNames.CSharp)]
+public class FixedArrayGenerator : IIncrementalGenerator
+{
+    private const string UsingSystem = "System";
+    private const string UsingSystemRuntimeInterop = "System.Runtime.InteropServices";
+    private const string AttributeNamespace = "System.Extensions";
+    private const string AttributeName = "GenerateFixedArrayAttribute";
+    private const string AttributeShortName = "GenerateFixedArray";
+    private const string Array = "Array";
+    private const string Public = "public";
+    private const string Struct = "struct";
+    private const string Required = "required";
+    private const string Size = "Size";
+    private const string Int = "int";
+    private const string TType = "T";
+
+    public void Initialize(IncrementalGeneratorInitializationContext context)
+    {
+        context.RegisterPostInitializationOutput(context =>
+        {
+            var compilationUnitBuilder = SyntaxBuilder.CreateCompilationUnit()
+                .WithNamespace(
+                SyntaxBuilder.CreateNamespace(AttributeNamespace)
+                    .WithClass(SyntaxBuilder.CreateClass(AttributeName)
+                        .WithModifier(Public)
+                        .WithTypeParameter(SyntaxBuilder.CreateTypeParameter(TType))
+                        .WithTypeParameterConstraint(SyntaxBuilder.CreateTypeParameterConstraint(TType)
+                            .WithType(Struct))
+                        .WithConstructor(SyntaxBuilder.CreateConstructor(AttributeName)
+                            .WithModifier(Public))
+                        .WithAttribute(SyntaxBuilder.CreateAttribute("AttributeUsage")
+                            .WithArgument(AttributeTargets.Assembly)
+                            .WithArgument("Inherited", false)
+                            .WithArgument("AllowMultiple", false))
+                        .WithProperty(SyntaxBuilder.CreateProperty(Int, Size)
+                            .WithModifier(Public)
+                            .WithModifier(Required)
+                            .WithAccessor(SyntaxBuilder.CreateGetter())
+                            .WithAccessor(SyntaxBuilder.CreateSetter()))
+                        .WithBaseClass(nameof(Attribute))));
+            var compilationUnitSyntax = compilationUnitBuilder.Build();
+            var source = compilationUnitSyntax.ToFullString();
+            context.AddSource($"{AttributeName}.g", source);
+        });
+
+        context.RegisterSourceOutput(context.CompilationProvider, (sourceProductionContext, compilation) =>
+        {
+            var assemblyAttributes =
+            compilation.Assembly.GetAttributes().Where(a => a.AttributeClass != null &&
+                        (a.AttributeClass.Name == AttributeName || a.AttributeClass.Name == AttributeShortName));
+
+            foreach(var attr in assemblyAttributes)
+            {
+                // Extract the type argument (T) from GenerateFixedArrayAttribute<T>
+                var namedTypeSymbol = attr.AttributeClass as INamedTypeSymbol;
+                if (namedTypeSymbol is null || namedTypeSymbol.TypeArguments.Length != 1)
+                {
+                    continue;
+                }
+
+                var targetType = namedTypeSymbol.TypeArguments[0].ToDisplayString(SymbolDisplayFormat.MinimallyQualifiedFormat);
+                // Extract the Size parameter from the named arguments.
+                int? fixedSize = default;
+                foreach (var arg in attr.NamedArguments)
+                {
+                    if (arg.Key == Size && arg.Value.Value is int intValue)
+                    {
+                        fixedSize = intValue;
+                        break;
+                    }
+                }
+
+                if (fixedSize is null)
+                {
+                    // As Size is required, skip if not provided.
+                    continue;
+                }
+
+                Execute(sourceProductionContext, targetType, (int)fixedSize);
+            }
+        });
+    }
+
+    private static void Execute(SourceProductionContext sourceProductionContext, string targetType, int size)
+    {
+        var capitalizedType = targetType.ToUpperInvariant()[0] + targetType.Substring(1);
+        var structName = $"{Array}{size}{capitalizedType}";
+        var builder = new StringBuilder();
+        builder.AppendLine($"using {UsingSystem};");
+        builder.AppendLine($"using {UsingSystemRuntimeInterop};");
+        builder.AppendLine();
+        builder.AppendLine($"namespace {AttributeNamespace}");
+        builder.AppendLine("{");
+        builder.AppendLine("    [StructLayout(LayoutKind.Sequential, Pack = 1)]");
+        builder.AppendLine($"    public unsafe struct {structName}");
+        builder.AppendLine("    {");
+        builder.AppendLine($"        private const int Size = {size};");
+        builder.AppendLine();
+        builder.AppendLine($"        private fixed {targetType} elements[Size];");
+        builder.AppendLine();
+        builder.AppendLine("        public int Length => Size;");
+        builder.AppendLine();
+        builder.AppendLine($"        public ref {targetType} this[int index]");
+        builder.AppendLine("        {");
+        builder.AppendLine("            get");
+        builder.AppendLine("            {");
+        builder.AppendLine("                if (index >= Size) throw new IndexOutOfRangeException();");
+        builder.AppendLine($"                fixed ({targetType}* ptr = this.elements)");
+        builder.AppendLine("                {");
+        builder.AppendLine("                    return ref ptr[index];");
+        builder.AppendLine("                }");
+        builder.AppendLine("            }");
+        builder.AppendLine("        }");
+        builder.AppendLine();
+        builder.AppendLine($"        public Span<{targetType}> AsSpan()");
+        builder.AppendLine("        {");
+        builder.AppendLine($"            fixed ({targetType}* ptr = this.elements)");
+        builder.AppendLine("            {");
+        builder.AppendLine($"                return new Span<{targetType}>(ptr, Size);");
+        builder.AppendLine("            }");
+        builder.AppendLine("        }");
+        builder.AppendLine();
+        builder.AppendLine($"        public static {structName} FromBytes(byte[] array)");
+        builder.AppendLine("        {");
+        builder.AppendLine($"            var arr = default({structName});");
+        builder.AppendLine("            array.AsSpan().CopyTo(arr.AsSpan());");
+        builder.AppendLine("            return arr;");
+        builder.AppendLine("        }");
+        builder.AppendLine("    }");
+        builder.AppendLine("}");
+
+        sourceProductionContext.AddSource($"{structName}.g.cs", builder.ToString());
+    }
+}
+#nullable disable
@@ -5,7 +5,7 @@
    <GeneratePackageOnBuild>true</GeneratePackageOnBuild>
    <Authors>Alexandru Macocian</Authors>
    <Description>Source generators extensions for netstandard2.0.</Description>
-    <Version>0.1.2</Version>
+    <Version>0.1.3</Version>
    <LangVersion>latest</LangVersion>
    <EnableNETAnalyzers>true</EnableNETAnalyzers>
    <EnforceExtendedAnalyzerRules>true</EnforceExtendedAnalyzerRules>
@@ -18,7 +18,7 @@
      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
    </PackageReference>
    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="4.8.0" PrivateAssets="all" />
-    <PackageReference Include="Sybil" Version="0.6.0" PrivateAssets="all" />
+    <PackageReference Include="Sybil" Version="0.8.4" PrivateAssets="all" />
  </ItemGroup>

  <ItemGroup>