src/Typecheck.hs

@@ -9,24 +9,27 @@ typeCheckCompilationUnit classes = map (`typeCheckClass` classes) classes
 typeCheckClass :: Class -> [Class] -> Class
 typeCheckClass (Class className methods fields) classes =
     let
-        -- Create a symbol table from class fields and method entries
-        -- TODO: Maybe remove method entries from the symbol table?
-        methodEntries = [(methodName, className) | MethodDeclaration _ methodName _ _ <- methods]
-        initalSymTab = ("this", className) : methodEntries
+        -- Fields dont need to be added to the symtab because they are looked upon automatically under this if its not a declared local variable
+        -- TODO: Maybe remove method entries from the symbol table? I dont think we need them but if yes the next line would be
+        -- initalSymTab = ("this", className) : methodEntries
+        -- methodEntries = [(methodName, className) | MethodDeclaration _ methodName _ _ <- methods]
+        initalSymTab = [("this", className)]
         checkedMethods = map (\method -> typeCheckMethodDeclaration method initalSymTab classes) methods
     in Class className checkedMethods fields
 
 typeCheckMethodDeclaration :: MethodDeclaration -> [(Identifier, DataType)] -> [Class] -> MethodDeclaration
-typeCheckMethodDeclaration (MethodDeclaration retType name params body) classFields classes =
+typeCheckMethodDeclaration (MethodDeclaration retType name params body) symtab classes =
     let
         methodParams = [(identifier, dataType) | ParameterDeclaration dataType identifier <- params]
-        initialSymtab = ("thisMeth", retType) : classFields ++ methodParams
+        initialSymtab = ("thisMeth", retType) : symtab ++ methodParams
         checkedBody = typeCheckStatement body initialSymtab classes
         bodyType = getTypeFromStmt checkedBody
     in if bodyType == retType || (bodyType == "void" && retType == "void") || (bodyType == "null" && isObjectType retType) || isSubtype bodyType retType classes
        then MethodDeclaration retType name params checkedBody
        else error $ "Method Declaration: Return type mismatch in method " ++ name ++ ": expected " ++ retType ++ ", found " ++ bodyType
 
+-- TODO: It could be that TypeCheckVariableDeclaration is missing. If it comes up -> just check wether the type is correct. The maybe expression needs to be
+-- checked as well. Also if its a class type, check wether the class exists.
 
 -- ********************************** Type Checking: Expressions **********************************
 
@@ -36,7 +39,6 @@ typeCheckExpression (CharacterLiteral c) _ _ = TypedExpression "char" (Character
 typeCheckExpression (BooleanLiteral b) _ _ = TypedExpression "boolean" (BooleanLiteral b)
 typeCheckExpression NullLiteral _ _ = TypedExpression "null" NullLiteral
 typeCheckExpression (Reference id) symtab classes =
-  -- TODO: maybe maje exception for "this" in first lookup?
   case lookup id symtab of
     Just t -> TypedExpression t (LocalVariable id)
     Nothing ->
@@ -47,7 +49,7 @@ typeCheckExpression (Reference id) symtab classes =
             Just (Class _ _ fields) ->
               let fieldTypes = [dt | VariableDeclaration dt fieldId _ <- fields, fieldId == id]
               in case fieldTypes of
-                [fieldType] -> TypedExpression fieldType (FieldVariable id)
+                [fieldType] -> TypedExpression fieldType (BinaryOperation NameResolution (LocalVariable "this") (FieldVariable id))
                 [] -> error $ "Field '" ++ id ++ "' not found in class '" ++ className ++ "'"
                 _ -> error $ "Ambiguous reference to field '" ++ id ++ "' in class '" ++ className ++ "'"
             Nothing -> error $ "Class '" ++ className ++ "' not found for 'this'"
@@ -272,7 +274,7 @@ typeCheckStatement (Block statements) symtab classes =
         -- Initial accumulator: empty statements list, initial symbol table, empty types list
         (checkedStatements, finalSymtab, collectedTypes) = foldl processStatements ([], symtab, []) statements
 
-        -- Determine the block's type: unify all collected types, default to "Void" if none
+        -- Determine the block's type: unify all collected types, default to "void" if none (UpperBound)
         blockType = if null collectedTypes then "void" else foldl1 unifyReturnTypes collectedTypes
 
     in TypedStatement blockType (Block checkedStatements)