Generate tagged enums in C# client code (#1421)

crates/bindings-csharp/BSATN.Runtime/src/Attrs.cs

@@ -15,6 +15,6 @@ public sealed class TypeAttribute : Attribute { }
 
     // This could be an interface, but using `record` forces C# to check that it can
     // only be applied on types that are records themselves.
-    public record TaggedEnum<Variants>
+    public abstract record TaggedEnum<Variants>
         where Variants : struct, ITuple { }
 }

crates/cli/src/subcommands/generate/csharp.rs

@@ -113,7 +113,8 @@ fn default_init(ctx: &GenCtx, ty: &AlgebraicType) -> &'static str {
             if sum_type.as_option().is_some() || sum_type.is_simple_enum() {
                 ""
             } else {
-                unimplemented!()
+                // TODO: generate some proper default here (what would it be for tagged enums?).
+                " = null!"
             }
         }
         // For product types, we can just use the default constructor.
@@ -198,20 +199,7 @@ impl CsharpAutogen {
     }
 }
 
-pub fn autogen_csharp_sum(
-    /* will be used in future for tagged enum */ _ctx: &GenCtx,
-    name: &str,
-    sum_type: &SumType,
-    namespace: &str,
-) -> String {
-    if sum_type.is_simple_enum() {
-        autogen_csharp_enum(name, sum_type, namespace)
-    } else {
-        unimplemented!();
-    }
-}
-
-pub fn autogen_csharp_enum(name: &str, sum_type: &SumType, namespace: &str) -> String {
+pub fn autogen_csharp_sum(ctx: &GenCtx, name: &str, sum_type: &SumType, namespace: &str) -> String {
     let mut output = CsharpAutogen::new(namespace, &[]);
 
     let mut sum_namespace = None;
@@ -237,17 +225,47 @@ pub fn autogen_csharp_enum(name: &str, sum_type: &SumType, namespace: &str) -> S
     }
 
     writeln!(output, "[SpacetimeDB.Type]");
-    writeln!(output, "public enum {sum_type_name}");
-    indented_block(&mut output, |output| {
-        for variant in &*sum_type.variants {
-            let variant_name = variant
-                .name
-                .as_ref()
-                .expect("All sum variants should have names!")
-                .replace("r#", "");
-            writeln!(output, "{variant_name},");
+
+    if sum_type.is_simple_enum() {
+        writeln!(output, "public enum {sum_type_name}");
+        indented_block(&mut output, |output| {
+            for variant in &*sum_type.variants {
+                let variant_name = variant
+                    .name
+                    .as_ref()
+                    .expect("All sum variants should have names!")
+                    .replace("r#", "");
+                writeln!(output, "{variant_name},");
+            }
+        });
+    } else {
+        write!(
+            output,
+            "public partial record {sum_type_name} : SpacetimeDB.TaggedEnum<("
+        );
+        {
+            indent_scope!(output);
+            for (i, variant) in sum_type.variants.iter().enumerate() {
+                if i != 0 {
+                    write!(output, ",");
+                }
+                writeln!(output);
+                if variant.is_unit() {
+                    write!(output, "SpacetimeDB.Unit");
+                } else {
+                    write!(output, "{}", ty_fmt(ctx, &variant.algebraic_type, namespace));
+                }
+                let variant_name = variant
+                    .name
+                    .as_ref()
+                    .expect("All sum variants should have names!")
+                    .replace("r#", "");
+                write!(output, " {variant_name}");
+            }
         }
-    });
+        writeln!(output);
+        writeln!(output, ")>;");
+    }
 
     if sum_namespace.is_some() {
         for _ in 0..2 {

crates/cli/src/subcommands/generate/typescript.rs

@@ -453,7 +453,7 @@ pub fn autogen_typescript_sum(ctx: &GenCtx, name: &str, sum_type: &SumType) -> S
                 ),
                 _ => writeln!(
                     output,
-                    "export const {variant_name} = (value: {a_type}): {variant_name} => {{ return {{ tag: \"{variant_name}\", value }} }};"
+                    "export const {variant_name} = (value: {a_type}): {variant_name} => ({{ tag: \"{variant_name}\", value }});"
                 ),
             };
         }

crates/cli/tests/snapshots/codegen__codegen_csharp.snap

@@ -203,6 +203,31 @@ namespace SpacetimeDB
 	}
 }
 '''
+"NamespaceTestF.cs" = '''
+// THIS FILE IS AUTOMATICALLY GENERATED BY SPACETIMEDB. EDITS TO THIS FILE
+// WILL NOT BE SAVED. MODIFY TABLES IN RUST INSTEAD.
+// <auto-generated />
+
+#nullable enable
+
+using System;
+
+namespace SpacetimeDB
+{
+	public partial class Namespace
+	{
+		public partial class Types
+		{
+			[SpacetimeDB.Type]
+			public partial record TestF : SpacetimeDB.TaggedEnum<(
+				SpacetimeDB.Unit Foo,
+				SpacetimeDB.Unit Bar,
+				string Baz
+			)>;
+		}
+	}
+}
+'''
 "PkMultiIdentity.cs" = '''
 // THIS FILE IS AUTOMATICALLY GENERATED BY SPACETIMEDB. EDITS TO THIS FILE
 // WILL NOT BE SAVED. MODIFY TABLES IN RUST INSTEAD.
@@ -599,16 +624,17 @@ namespace SpacetimeDB
 		public SpacetimeDB.TestA Arg = new();
 		public SpacetimeDB.TestB Arg2 = new();
 		public SpacetimeDB.Namespace.Types.TestC Arg3;
+		public SpacetimeDB.Namespace.TestF Arg4 = null!;
 	}
 
 	public static partial class Reducer
 	{
-		public delegate void TestHandler(ReducerEvent reducerEvent, SpacetimeDB.TestA arg, SpacetimeDB.TestB arg2, SpacetimeDB.Namespace.Types.TestC arg3);
+		public delegate void TestHandler(ReducerEvent reducerEvent, SpacetimeDB.TestA arg, SpacetimeDB.TestB arg2, SpacetimeDB.Namespace.Types.TestC arg3, SpacetimeDB.Namespace.TestF arg4);
 		public static event TestHandler? OnTestEvent;
 
-		public static void Test(SpacetimeDB.TestA arg, SpacetimeDB.TestB arg2, SpacetimeDB.Namespace.Types.TestC arg3)
+		public static void Test(SpacetimeDB.TestA arg, SpacetimeDB.TestB arg2, SpacetimeDB.Namespace.Types.TestC arg3, SpacetimeDB.Namespace.TestF arg4)
 		{
-			SpacetimeDBClient.instance.InternalCallReducer(new TestArgsStruct { Arg = arg, Arg2 = arg2, Arg3 = arg3 });
+			SpacetimeDBClient.instance.InternalCallReducer(new TestArgsStruct { Arg = arg, Arg2 = arg2, Arg3 = arg3, Arg4 = arg4 });
 		}
 
 		public static bool OnTest(ReducerEvent reducerEvent, TestArgsStruct args)
@@ -618,7 +644,8 @@ namespace SpacetimeDB
 				reducerEvent,
 				args.Arg,
 				args.Arg2,
-				args.Arg3
+				args.Arg3,
+				args.Arg4
 			);
 			return true;
 		}

crates/cli/tests/snapshots/codegen__codegen_rust.snap

@@ -301,6 +301,7 @@ use spacetimedb_sdk::spacetime_module::SpacetimeModule;
 use std::sync::Arc;
 
 pub mod namespace.test_c;
+pub mod namespace.test_f;
 pub mod test_b;
 pub mod pk_multi_identity;
 pub mod point;
@@ -317,6 +318,7 @@ pub mod repeating_test_reducer;
 pub mod test_reducer;
 
 pub use namespace.test_c::*;
+pub use namespace.test_f::*;
 pub use test_b::*;
 pub use pk_multi_identity::*;
 pub use point::*;
@@ -435,6 +437,29 @@ pub enum Namespace.testC {
 
 }
 '''
+"namespace_test_f.rs" = '''
+// THIS FILE IS AUTOMATICALLY GENERATED BY SPACETIMEDB. EDITS TO THIS FILE
+// WILL NOT BE SAVED. MODIFY TABLES IN RUST INSTEAD.
+
+#![allow(unused_imports)]use spacetimedb_sdk::{
+	Address,
+	sats::{ser::Serialize, de::Deserialize},
+	table::{TableType, TableIter, TableWithPrimaryKey},
+	reducer::{Reducer, ReducerCallbackId, Status},
+	identity::Identity,
+	spacetimedb_lib,
+	anyhow::{Result, anyhow},
+};
+
+#[derive(Serialize, Deserialize, Clone, PartialEq, Debug)]
+pub enum Namespace.testF {
+	Foo,
+
+	Bar,
+
+	Baz(String),
+}
+'''
 "pk_multi_identity.rs" = '''
 // THIS FILE IS AUTOMATICALLY GENERATED BY SPACETIMEDB. EDITS TO THIS FILE
 // WILL NOT BE SAVED. MODIFY TABLES IN RUST INSTEAD.
@@ -837,6 +862,7 @@ impl TestE {
 	anyhow::{Result, anyhow},
 };
 use super::namespace.test_c::Namespace.testC;
+use super::namespace.test_f::Namespace.testF;
 use super::test_a::TestA;
 use super::test_b::TestB;
 
@@ -845,6 +871,7 @@ pub struct TestArgs {
 	pub arg: TestA,
 	pub arg_2: TestB,
 	pub arg_3: Namespace.testC,
+	pub arg_4: Namespace.testF,
 }
 
 impl Reducer for TestArgs {
@@ -856,22 +883,25 @@ pub fn test(
 	arg: TestA,
 	arg_2: TestB,
 	arg_3: Namespace.testC,
+	arg_4: Namespace.testF,
 ) {
 		TestArgs {
 		arg,
 		arg_2,
 		arg_3,
+		arg_4,
 }	.invoke();
 }
 
 #[allow(unused)]
-pub fn on_test(mut __callback: impl FnMut(&Identity, Option<Address>, &Status, &TestA, &TestB, &Namespace.testC) + Send + 'static) -> ReducerCallbackId<TestArgs> 
+pub fn on_test(mut __callback: impl FnMut(&Identity, Option<Address>, &Status, &TestA, &TestB, &Namespace.testC, &Namespace.testF) + Send + 'static) -> ReducerCallbackId<TestArgs> 
 {
 		TestArgs::on_reducer(move |__identity, __addr, __status, __args| {
 		let TestArgs {
 			arg,
 			arg_2,
 			arg_3,
+			arg_4,
 }		 = __args;
 __callback(
 						__identity,
@@ -880,18 +910,20 @@ __callback(
 			arg,
 			arg_2,
 			arg_3,
+			arg_4,
 );
 })
 }
 
 #[allow(unused)]
-pub fn once_on_test(__callback: impl FnOnce(&Identity, Option<Address>, &Status, &TestA, &TestB, &Namespace.testC) + Send + 'static) -> ReducerCallbackId<TestArgs> 
+pub fn once_on_test(__callback: impl FnOnce(&Identity, Option<Address>, &Status, &TestA, &TestB, &Namespace.testC, &Namespace.testF) + Send + 'static) -> ReducerCallbackId<TestArgs> 
 {
 		TestArgs::once_on_reducer(move |__identity, __addr, __status, __args| {
 		let TestArgs {
 			arg,
 			arg_2,
 			arg_3,
+			arg_4,
 }		 = __args;
 __callback(
 						__identity,
@@ -900,6 +932,7 @@ __callback(
 			arg,
 			arg_2,
 			arg_3,
+			arg_4,
 );
 })
 }