C#: split table codegen logic from type codegen logic (#1573)

Co-authored-by: Zeke Foppa <bfops@users.noreply.github.com>

Author: RReverser

crates/bindings-csharp/BSATN.Codegen/Type.cs

@@ -40,7 +40,7 @@ public static string SymbolToName(ISymbol symbol)
     }
 
     public static void RegisterSourceOutputs(
-        this IncrementalValuesProvider<KeyValuePair<string, string>> methods,
+        this IncrementalValuesProvider<Scope.Extensions> methods,
         IncrementalGeneratorInitializationContext context
     )
     {
@@ -49,12 +49,12 @@ IncrementalGeneratorInitializationContext context
             (context, method) =>
             {
                 context.AddSource(
-                    $"{string.Join("_", method.Key.Split(Path.GetInvalidFileNameChars()))}.cs",
+                    $"{string.Join("_", method.FullName.Split(Path.GetInvalidFileNameChars()))}.cs",
                     $"""
                     // <auto-generated />
                     #nullable enable
 
-                    {method.Value}
+                    {method}
                     """
                 );
             }
@@ -155,38 +155,24 @@ static string GetTypeInfoForNamedType(INamedTypeSymbol type)
         }
     }
 
-    public static IEnumerable<IFieldSymbol> GetFields(
-        TypeDeclarationSyntax typeSyntax,
-        INamedTypeSymbol type
+    // Polyfill for .NET methods from .NET Standard 2.1+:
+    private static StringBuilder AppendJoin<T>(
+        this StringBuilder sb,
+        string separator,
+        IEnumerable<T> values
     )
     {
-        // Note: we could use naively use `type.GetMembers()` to get all fields of the type,
-        // but some users add their own fields in extra partial declarations like this:
-        //
-        // ```csharp
-        // [SpacetimeDB.Type]
-        // partial class MyType
-        // {
-        //     public int TableField;
-        // }
-        //
-        // partial class MyType
-        // {
-        //     public int ExtraField;
-        // }
-        // ```
-        //
-        // In this scenario, only fields declared inside the declaration with the `[SpacetimeDB.Type]` attribute
-        // should be considered as BSATN fields, and others are expected to be ignored.
-        //
-        // To achieve this, we need to walk over the annotated type syntax node, collect the field names,
-        // and look up the resolved field symbols only for those fields.
-        return typeSyntax
-            .Members.OfType<FieldDeclarationSyntax>()
-            .SelectMany(f => f.Declaration.Variables)
-            .SelectMany(v => type.GetMembers(v.Identifier.Text))
-            .OfType<IFieldSymbol>()
-            .Where(f => !f.IsStatic);
+        var first = true;
+        foreach (var value in values)
+        {
+            if (!first)
+            {
+                sb.Append(separator);
+            }
+            first = false;
+            sb.Append(value);
+        }
+        return sb;
     }
 
     // Borrowed & modified code for generating in-place extensions for partial structs/classes/etc. Source:
@@ -232,71 +218,70 @@ public Scope(MemberDeclarationSyntax? node)
 
         public readonly record struct TypeScope(string Keyword, string Name, string Constraints);
 
-        public string GenerateExtensions(
-            string contents,
-            string? interface_ = null,
-            string? extraAttrs = null
-        )
+        public sealed record Extensions(Scope Scope, string FullName)
         {
-            var sb = new StringBuilder();
+            public readonly StringBuilder Contents = new();
+            public readonly List<string> BaseTypes = [];
+            public readonly List<string> ExtraAttrs = [];
 
-            // Join all namespaces into a single namespace statement, starting with the outermost.
-            if (namespaces.Length > 0)
+            public override string ToString()
             {
-                sb.Append("namespace ");
-                var first = true;
-                foreach (var ns in namespaces.Reverse())
+                var sb = new StringBuilder();
+
+                // Join all namespaces into a single namespace statement, starting with the outermost.
+                if (Scope.namespaces.Length > 0)
                 {
-                    if (!first)
-                    {
-                        sb.Append('.');
-                    }
-                    first = false;
-                    sb.Append(ns);
+                    sb.Append("namespace ")
+                        .AppendJoin(".", Scope.namespaces.Reverse())
+                        .AppendLine(" {");
                 }
-                sb.AppendLine(" {");
-            }
 
-            // Loop through the full parent type hiearchy, starting with the outermost.
-            foreach (var (i, typeScope) in typeScopes.Select((ts, i) => (i, ts)).Reverse())
-            {
-                if (i == 0 && extraAttrs is not null)
+                // Loop through the full parent type hiearchy, starting with the outermost.
+                foreach (
+                    var (i, typeScope) in Scope.typeScopes.Select((ts, i) => (i, ts)).Reverse()
+                )
                 {
-                    sb.AppendLine(extraAttrs);
-                }
+                    if (i == 0)
+                    {
+                        foreach (var extraAttr in ExtraAttrs)
+                        {
+                            sb.AppendLine(extraAttr);
+                        }
+                    }
 
-                sb.Append("partial ")
-                    .Append(typeScope.Keyword) // e.g. class/struct/record
-                    .Append(' ')
-                    .Append(typeScope.Name) // e.g. Outer/Generic<T>
-                    .Append(' ');
+                    sb.Append("partial ")
+                        .Append(typeScope.Keyword) // e.g. class/struct/record
+                        .Append(' ')
+                        .Append(typeScope.Name) // e.g. Outer/Generic<T>
+                        .Append(' ');
 
-                if (i == 0 && interface_ is not null)
-                {
-                    sb.Append(" : ").Append(interface_);
+                    if (i == 0 && BaseTypes.Count > 0)
+                    {
+                        sb.Append(" : ").AppendJoin(", ", BaseTypes);
+                    }
+
+                    sb.Append(typeScope.Constraints).AppendLine(" {");
                 }
 
-                sb.Append(typeScope.Constraints).AppendLine(" {");
-            }
+                sb.AppendLine();
+                sb.Append(Contents);
+                sb.AppendLine();
 
-            sb.AppendLine();
-            sb.Append(contents);
-            sb.AppendLine();
+                // We need to "close" each of the parent types, so write
+                // the required number of '}'
+                foreach (var typeScope in Scope.typeScopes)
+                {
+                    sb.Append("} // ").AppendLine(typeScope.Name);
+                }
 
-            // We need to "close" each of the parent types, so write
-            // the required number of '}'
-            foreach (var typeScope in typeScopes)
-            {
-                sb.Append("} // ").AppendLine(typeScope.Name);
-            }
+                // Close the namespace, if we had one
+                if (Scope.namespaces.Length > 0)
+                {
+                    sb.AppendLine("} // namespace");
+                }
 
-            // Close the namespace, if we had one
-            if (namespaces.Length > 0)
-            {
-                sb.AppendLine("} // namespace");
+                return sb.ToString();
             }
-
-            return sb.ToString();
         }
     }
 }

crates/bindings-csharp/BSATN.Codegen/Utils.cs

@@ -1,5 +1,4 @@
 using System.Text;
-using SpacetimeDB;
 
 namespace SpacetimeDB.BSATN;