From 6133e58226b84aae86fcd38bd745b48d63e0eea6 Mon Sep 17 00:00:00 2001
From: Your Name <you@example.com>
Date: Wed, 11 Feb 2026 09:07:13 +0100
Subject: [PATCH] FormulaElement as abstract class

---
 TODO.md                          |  3 ++-
 flutterw                         |  2 +-
 lib/corpus.dart                  |  3 ++-
 lib/defaults/default_corpus.dart |  6 ++++--
 lib/formula_models.dart          | 18 ++++++++++--------
 5 files changed, 19 insertions(+), 13 deletions(-)

diff --git a/TODO.md b/TODO.md
index 500228a..f67a06e 100644
--- a/TODO.md
+++ b/TODO.md
@@ -17,7 +17,8 @@
 - Drift files have a lot of duplicate code. "web" version is the same as native version, only _openConnection is diferrent. Refactor to not duplicate code.
 - [X] Create Formula.toStringLiteral. It is the reverse of Formula.fromSet( Formula.fromArrayStringLiteral(string)[0] )
 - [X] Create UnitSpec.toStringLiteral, like Formula.toStringLiteral
-- [ ] Make Formula and UnitSpec subclasses of FormulaElement. Change return type of functions that return Object to FormulaElement if necessary.
+- [X] Make Formula and UnitSpec subclasses of FormulaElement. Change return type of functions that return Object to FormulaElement if necessary.
+- [ ] Define toStringLiteral in FormulaElement.
 - Database file location:
   - [ ] In linux, the sqlite database file will be located following rules at https://specifications.freedesktop.org/basedir/latest/
   - [ ] In Windows, the sqlite database file will be in %appdata%/Roaming
diff --git a/flutterw b/flutterw
index 9fb2dd0..e4b5f02 100755
--- a/flutterw
+++ b/flutterw
@@ -1,7 +1,7 @@
 #!/bin/bash
 
 set -e
-set -x
+#set -x
 
 BUILDCACHE=./.build-container-cache
 DOCKERFILE=./docker/Dockerfile
diff --git a/lib/corpus.dart b/lib/corpus.dart
index 62fcf01..fb80422 100644
--- a/lib/corpus.dart
+++ b/lib/corpus.dart
@@ -1,6 +1,7 @@
 import 'package:d4rt/d4rt.dart';
 import 'package:collection/collection.dart';
 import 'package:d4rt_formulas/d4rt_formulas.dart';
+import 'formula_models.dart';
 
 class Multimap<K, V> extends DelegatingMap<K, List<V>> {
   final Map<K, List<V>> _map;
@@ -182,7 +183,7 @@ class Corpus{
 
   /// Loads formula elements, making sure to load units first, then formulas
   /// to avoid dependency issues.
-  void loadFormulaElements(List<Object> elements) {
+  void loadFormulaElements(List<FormulaElement> elements) {
     List<UnitSpec> units = [];
     List<Formula> formulas = [];
 
diff --git a/lib/defaults/default_corpus.dart b/lib/defaults/default_corpus.dart
index 40f75ec..e9801e3 100644
--- a/lib/defaults/default_corpus.dart
+++ b/lib/defaults/default_corpus.dart
@@ -39,7 +39,8 @@ Future<Corpus> createDefaultCorpus() async{
       print( "Loading units from $unitRes");
       final literal = await loadResourceAsString(unitRes);
       final units = UnitSpec.fromArrayStringLiteral(literal);
-      corpus.loadFormulaElements(units);
+      final formulaElements = units.cast<FormulaElement>();
+      corpus.loadFormulaElements(formulaElements);
     }
   }
 
@@ -49,7 +50,8 @@ Future<Corpus> createDefaultCorpus() async{
     for (final formRes in formulaResources) {
       final literal = await loadResourceAsString(formRes);
       final formulas = Formula.fromArrayStringLiteral(literal);
-      corpus.loadFormulaElements(formulas);
+      final formulaElements = formulas.cast<FormulaElement>();
+      corpus.loadFormulaElements(formulaElements);
     }
   }
 
diff --git a/lib/formula_models.dart b/lib/formula_models.dart
index 34b7499..ede7ca5 100644
--- a/lib/formula_models.dart
+++ b/lib/formula_models.dart
@@ -38,21 +38,21 @@ List<Object?> parseD4rtLiteral(String arrayStringLiteral) {
 
 /// Parses corpus elements from an array string literal.
 /// Determines if each element is a formula or a unit and converts accordingly.
-List<Object> parseCorpusElements(String arrayStringLiteral) {
+List<FormulaElement> parseCorpusElements(String arrayStringLiteral) {
   final List<Object?> elements = parseD4rtLiteral(arrayStringLiteral);
-  
-  final List<Object> result = [];
+
+  final List<FormulaElement> result = [];
   for (final element in elements) {
     if (element is Map<Object?, Object?>) {
       // Check if it's a formula by looking for required formula properties
       // Formulas typically have 'd4rtCode' and 'input'/'output' properties
       if (element.containsKey('d4rtCode')) {
         result.add(Formula.fromSet(element));
-      } 
+      }
       // Units typically have 'name', 'symbol', and 'baseUnit' properties
       else if (element.containsKey('name') && element.containsKey('symbol')) {
         result.add(UnitSpec.fromSet(element));
-      } 
+      }
       else {
         throw ArgumentError('Unknown element type: $element');
       }
@@ -60,14 +60,16 @@ List<Object> parseCorpusElements(String arrayStringLiteral) {
       throw ArgumentError('Element must be a Map: $element');
     }
   }
-  
+
   return result;
 }
 
 typedef Number = double;
 
+/// Abstract base class for formula elements
+abstract class FormulaElement {}
 
-class UnitSpec {
+class UnitSpec extends FormulaElement {
   final String name;
   final String baseUnit;
   final String symbol;
@@ -217,7 +219,7 @@ class VariableSpec {
   }
 }
 
-class Formula {
+class Formula extends FormulaElement {
   final String name;
   final String? description;
   final List<VariableSpec> input;