Refactor folder structure

src/Runtime/Ghost.Generator/ComponentRegistrationGenerator.cs

@@ -0,0 +1,89 @@
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.CodeAnalysis.Text;
+using System.Collections.Immutable;
+using System.Linq;
+using System.Text;
+using System.Threading;
+
+namespace Ghost.Generator
+{
+    // TODO: this should be per assembly, not global
+    [Generator]
+    public class ComponentRegistrationGenerator : IIncrementalGenerator
+    {
+        public void Initialize(IncrementalGeneratorInitializationContext context)
+        {
+            // 1. Pipeline: Find all structs implementing IComponent
+            var componentCandidates = context.SyntaxProvider
+                .CreateSyntaxProvider(
+                    predicate: (s, _) => s is StructDeclarationSyntax,
+                    transform: GetComponentSymbol)
+                .Where(symbol => symbol != null)
+                .Collect();
+
+            // 4. Output: Generate the source using both pieces of data at once
+            context.RegisterSourceOutput(componentCandidates, GenerateRegistrationCode);
+        }
+
+        // Extraction Logic for Components
+        private static INamedTypeSymbol GetComponentSymbol(GeneratorSyntaxContext ctx, CancellationToken _)
+        {
+            var structSyntax = (StructDeclarationSyntax)ctx.Node;
+            if (!(ctx.SemanticModel.GetDeclaredSymbol(structSyntax) is INamedTypeSymbol symbol))
+            {
+                return null;
+            }
+
+            var iComponentSymbol = ctx.SemanticModel.Compilation.GetTypeByMetadataName("Ghost.Entities.IComponent");
+            if (iComponentSymbol == null)
+            {
+                return null;
+            }
+
+            foreach (var iface in symbol.AllInterfaces)
+            {
+                if (SymbolEqualityComparer.Default.Equals(iface, iComponentSymbol))
+                {
+                    return symbol;
+                }
+            }
+
+            return null;
+        }
+
+        // The Generation Logic (Stateless)
+        private static void GenerateRegistrationCode(SourceProductionContext context, ImmutableArray<INamedTypeSymbol> components)
+        {
+            if (components.IsDefaultOrEmpty)
+            {
+                return;
+            }
+
+            var name = $"g_component_registration";
+
+            var sb = new StringBuilder();
+            sb.Append($@"
+[global::System.ComponentModel.EditorBrowsable(global::System.ComponentModel.EditorBrowsableState.Never)]
+internal static class {name}
+{{
+    [global::System.Runtime.CompilerServices.ModuleInitializer]
+    public static void RegisterIComponentTypes()
+    {{");
+
+        foreach (var symbol in components.Distinct(SymbolEqualityComparer.Default))
+        {
+            if (symbol is null) continue;
+
+            sb.Append($@"
+        global::Ghost.Entities.ComponentRegistry.GetOrRegisterComponentID<{symbol.ToDisplayString(SymbolDisplayFormat.FullyQualifiedFormat)}>();");
+        }
+
+        sb.Append(@"
+    }
+}");
+
+            context.AddSource($"{name}.gen.cs", SourceText.From(sb.ToString(), Encoding.UTF8));
+        }
+    }
+}