Java: Generate sealed interface for sum types

4 files changed, 46 insertions, 9 deletions

diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/output/generators/javatypes/JavaTypesGenerator.java b/src/main/java/org/zwobble/hobgoblin/compiler/output/generators/javatypes/JavaTypesGenerator.java
index 43e35b4..98d4c12 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/output/generators/javatypes/JavaTypesGenerator.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/output/generators/javatypes/JavaTypesGenerator.java
@@ -8,10 +8,7 @@ import org.zwobble.hobgoblin.compiler.builtins.BuiltinTypes;
 import org.zwobble.hobgoblin.compiler.output.CodeWriter;
 import org.zwobble.hobgoblin.compiler.output.generators.Generator;
 import org.zwobble.hobgoblin.compiler.output.java.JavaWriter;
-import org.zwobble.hobgoblin.compiler.output.java.ast.JavaRecordComponent;
-import org.zwobble.hobgoblin.compiler.output.java.ast.JavaRecordDeclaration;
-import org.zwobble.hobgoblin.compiler.output.java.ast.JavaCompilationUnit;
-import org.zwobble.hobgoblin.compiler.output.java.ast.JavaTypeRef;
+import org.zwobble.hobgoblin.compiler.output.java.ast.*;
 import org.zwobble.hobgoblin.compiler.types.*;
 
 import java.io.File;
@@ -90,6 +87,17 @@ public class JavaTypesGenerator implements Generator {
                 }
 
                 case TypedSumDefinitionNode sumDefinition -> {
+                    var javaCompilationUnit = new JavaCompilationUnit(
+                        packageParts,
+                        new JavaInterfaceDeclaration(
+                            sumDefinition.name(),
+                            sumDefinition.variants().stream()
+                                .map(variant -> generateTypeRef(variant.type()))
+                                .toList()
+                        )
+                    );
+
+                    javaCompilationUnits.add(javaCompilationUnit);
                 }
             }
         }
diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/output/java/JavaWriter.java b/src/main/java/org/zwobble/hobgoblin/compiler/output/java/JavaWriter.java
index 1de6950..17ff590 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/output/java/JavaWriter.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/output/java/JavaWriter.java
@@ -1,10 +1,7 @@
 package org.zwobble.hobgoblin.compiler.output.java;
 
 import org.zwobble.hobgoblin.compiler.output.CodeWriter;
-import org.zwobble.hobgoblin.compiler.output.java.ast.JavaCompilationUnit;
-import org.zwobble.hobgoblin.compiler.output.java.ast.JavaRecordDeclaration;
-import org.zwobble.hobgoblin.compiler.output.java.ast.JavaTypeDeclaration;
-import org.zwobble.hobgoblin.compiler.output.java.ast.JavaTypeRef;
+import org.zwobble.hobgoblin.compiler.output.java.ast.*;
 
 import java.io.IOException;
 
@@ -32,12 +29,35 @@ public class JavaWriter implements AutoCloseable {
 
     private void writeTypeDeclaration(JavaTypeDeclaration typeDeclaration) throws IOException {
         switch (typeDeclaration) {
+            case JavaInterfaceDeclaration interfaceDeclaration -> {
+                writeInterfaceDeclaration(interfaceDeclaration);
+            }
+
             case JavaRecordDeclaration recordDeclaration -> {
                 writeRecordDeclaration(recordDeclaration);
             }
         }
     }
 
+    private void writeInterfaceDeclaration(JavaInterfaceDeclaration interfaceDeclaration) throws IOException {
+        this.writer.write("public sealed interface ");
+        this.writer.write(interfaceDeclaration.name());
+        this.writer.write(" ");
+
+        writer.write("permits ");
+        writeWithSeparator(
+            interfaceDeclaration.permitsTypes(),
+            this::writeTypeRef,
+            () -> writer.write(", ")
+        );
+        writer.write(" ");
+
+        this.writer.write("{");
+        this.writer.newLine();
+        this.writer.write("}");
+        this.writer.newLine();
+    }
+
     private void writeRecordDeclaration(JavaRecordDeclaration recordDeclaration) throws IOException {
         this.writer.write("public record ");
         this.writer.write(recordDeclaration.name());
diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/output/java/ast/JavaInterfaceDeclaration.java b/src/main/java/org/zwobble/hobgoblin/compiler/output/java/ast/JavaInterfaceDeclaration.java
new file mode 100644
index 0000000..212fdbe
--- /dev/null
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/output/java/ast/JavaInterfaceDeclaration.java
@@ -0,0 +1,9 @@
+package org.zwobble.hobgoblin.compiler.output.java.ast;
+
+import java.util.List;
+
+public record JavaInterfaceDeclaration(
+    String name,
+    List<JavaTypeRef> permitsTypes
+) implements JavaTypeDeclaration {
+}
diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/output/java/ast/JavaTypeDeclaration.java b/src/main/java/org/zwobble/hobgoblin/compiler/output/java/ast/JavaTypeDeclaration.java
index cffb58b..1c2884e 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/output/java/ast/JavaTypeDeclaration.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/output/java/ast/JavaTypeDeclaration.java
@@ -1,5 +1,5 @@
 package org.zwobble.hobgoblin.compiler.output.java.ast;
 
-public sealed interface JavaTypeDeclaration permits JavaRecordDeclaration {
+public sealed interface JavaTypeDeclaration permits JavaInterfaceDeclaration, JavaRecordDeclaration {
     String name();
 }