src/ByteCode/ClassFile/Generator.hs

@@ -94,6 +94,11 @@ methodDescriptor (MethodDeclaration returntype _ parameters _) = let
         ++ ")"
         ++ methodParameterDescriptor returntype
 
+injectDefaultConstructor :: [MethodDeclaration] -> [MethodDeclaration]
+injectDefaultConstructor pre
+    | any (\(MethodDeclaration _ name _ _) -> name == "<init>") pre = pre
+    | otherwise = pre ++ [MethodDeclaration "void" "<init>" [] (TypedStatement "void" (Block []))]
+
 
 classBuilder :: ClassFileBuilder Class
 classBuilder (Class name methods fields) _ = let
@@ -117,9 +122,11 @@ classBuilder (Class name methods fields) _ = let
             attributes = []
         }
 
+        methodsWithInjectedConstructor = injectDefaultConstructor methods
+
         classFileWithFields = foldr fieldBuilder nakedClassFile fields
-        classFileWithMethods = foldr methodBuilder classFileWithFields methods
-        classFileWithAssembledMethods = foldr methodAssembler classFileWithMethods methods
+        classFileWithMethods = foldr methodBuilder classFileWithFields methodsWithInjectedConstructor
+        classFileWithAssembledMethods = foldr methodAssembler classFileWithMethods methodsWithInjectedConstructor
     in
         classFileWithAssembledMethods
 
@@ -232,7 +239,7 @@ assembleMethod (constants, ops, lvars) (MethodDeclaration _ name _ (TypedStateme
             init_ops = [Opaload 0]
         in
             (constants_a, init_ops ++ ops_a, lvars_a)
-assembleMethod _ (MethodDeclaration _ _ _ stmt) = error ("Block expected for method body, got: " ++ show stmt)
+assembleMethod _ (MethodDeclaration _ _ _ stmt) = error ("Block expected for method body, got: " ++ show stmt) 
 
 assembleStatement :: Assembler Statement
 assembleStatement (constants, ops, lvars) (TypedStatement stype (Return expr)) = case expr of