Handle boxing in Rust output

8 files changed, 63 insertions, 6 deletions

diff --git a/examples/03-inductive-data-types/hobgoblin.json5 b/examples/03-inductive-data-types/hobgoblin.json5
index 28269ad..12713d4 100644
--- a/examples/03-inductive-data-types/hobgoblin.json5
+++ b/examples/03-inductive-data-types/hobgoblin.json5
@@ -10,6 +10,10 @@
         generator: "java-types",
         path: "output/java/src/gen/java",
       },
+      {
+        generator: "rust-types",
+        path: "output/rust/src",
+      },
     ],
   },
 }
diff --git a/examples/03-inductive-data-types/output/rust/.gitignore b/examples/03-inductive-data-types/output/rust/.gitignore
new file mode 100644
index 0000000..ea8c4bf
--- /dev/null
+++ b/examples/03-inductive-data-types/output/rust/.gitignore
@@ -0,0 +1 @@
+/target
diff --git a/examples/03-inductive-data-types/output/rust/Cargo.lock b/examples/03-inductive-data-types/output/rust/Cargo.lock
new file mode 100644
index 0000000..9dc6e3e
--- /dev/null
+++ b/examples/03-inductive-data-types/output/rust/Cargo.lock
@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "example"
+version = "0.1.0"
diff --git a/examples/03-inductive-data-types/output/rust/Cargo.toml b/examples/03-inductive-data-types/output/rust/Cargo.toml
new file mode 100644
index 0000000..5d4c622
--- /dev/null
+++ b/examples/03-inductive-data-types/output/rust/Cargo.toml
@@ -0,0 +1,6 @@
+[package]
+name = "example"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
diff --git a/examples/03-inductive-data-types/output/rust/rust-toolchain.toml b/examples/03-inductive-data-types/output/rust/rust-toolchain.toml
new file mode 100644
index 0000000..4fedb95
--- /dev/null
+++ b/examples/03-inductive-data-types/output/rust/rust-toolchain.toml
@@ -0,0 +1,2 @@
+[toolchain]
+channel = "1.96"
diff --git a/examples/03-inductive-data-types/output/rust/src/arithmetic.rs b/examples/03-inductive-data-types/output/rust/src/arithmetic.rs
new file mode 100644
index 0000000..ab4049d
--- /dev/null
+++ b/examples/03-inductive-data-types/output/rust/src/arithmetic.rs
@@ -0,0 +1,15 @@
+// Generated by hobgoblin.
+
+pub enum Expression {
+    Add(std::boxed::Box<crate::arithmetic::Add>),
+    Const(crate::arithmetic::Const),
+}
+
+pub struct Add {
+    pub left: crate::arithmetic::Expression,
+    pub right: crate::arithmetic::Expression,
+}
+
+pub struct Const {
+    pub value: i32,
+}
diff --git a/examples/03-inductive-data-types/output/rust/src/main.rs b/examples/03-inductive-data-types/output/rust/src/main.rs
new file mode 100644
index 0000000..8c1f750
--- /dev/null
+++ b/examples/03-inductive-data-types/output/rust/src/main.rs
@@ -0,0 +1,13 @@
+mod arithmetic;
+
+use arithmetic::{Add, Const, Expression};
+
+fn main() {
+    let expression = Expression::Add(Box::new(Add {
+        left: Expression::Add(Box::new(Add {
+            left: Expression::Const(Const { value: 42 }),
+            right: Expression::Const(Const { value: 47 }),
+        })),
+        right: Expression::Const(Const { value: 52 }),
+    }));
+}
diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/output/generators/rusttypes/RustTypesGenerator.java b/src/main/java/org/zwobble/hobgoblin/compiler/output/generators/rusttypes/RustTypesGenerator.java
index 8798741..d4e7fd1 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/output/generators/rusttypes/RustTypesGenerator.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/output/generators/rusttypes/RustTypesGenerator.java
@@ -152,12 +152,21 @@ public class RustTypesGenerator implements Generator {
         var rustEnumName = generateTypeName(sumDefinition.name());
 
         var rustVariants = sumDefinition.variants().stream()
-            .map(variant -> new RustEnumVariant(
-                generateVariantName(variant.type().value()),
-                new RustEnumVariantTuple(List.of(
-                    new RustTupleField(generateRustTypeExpression(variant.type(), context))
-                ))
-            ))
+            .map(variant -> {
+                var variantType = generateRustTypeExpression(variant.type(), context);
+
+                if (variant.isBox()) {
+                    variantType = RustTypePath.of("std", "boxed", "Box")
+                        .withArgs(List.of(variantType));
+                }
+
+                return new RustEnumVariant(
+                    generateVariantName(variant.type().value()),
+                    new RustEnumVariantTuple(List.of(
+                        new RustTupleField(variantType)
+                    ))
+                );
+            })
             .toList();
 
         var rustEnum = new RustEnum(rustEnumName, rustVariants, sumDefinition.docComment());