Better formula elements loading

TODO.md

@@ -2,12 +2,13 @@
 [x] Means done
 
 - [X] Unify error reporting. Create class ErrorHandler that get notified of every catched exception. This class prints the exception in stdout.
-- [ ] Make formula description collapsable in FormulaScreen. Initialy, the description is visible, but the user can hide it.
+- [X] Make formula description collapsable in FormulaScreen. Initialy, the description is visible, but the user can hide it.
 - Refactor formula and unit loading:
-  - [ ] Create method `List<Object?> parseD4rtLiteral(String arrayStringLiteral). It parses a d4rt array literal (containing maps and arrays) to a List<Object?> using d4rt
-  - [ ] Remove `fromArrayStringLiteral` from UnitSpec and Formula.
-  - [ ] Create function `List<Object> parseCorpusElements(String arrayStringLiteral)`. It uses parseD4rtLiteral and determines if each element of the array is a formula or a unit. Then converts the objects with Formula.fromSet or UnitSpec.fromSet.
-  - [ ] Create method loadFormulaElements( List<Object> elements). Tipically receives the list from parseCorpusElements(). It loads the units first, then the formulas, to avoid missing dependencies.
+  - [X] Create method `List<Object?> parseD4rtLiteral(String arrayStringLiteral). It parses a d4rt array literal (containing maps and arrays) to a List<Object?> using d4rt
+  - [X] Make `fromArrayStringLiteral` from UnitSpec and Formula to use parseD4rtLiteral
+  - [X] Create function `List<Object> parseCorpusElements(String arrayStringLiteral)`. It uses parseD4rtLiteral and determines if each element of the array is a formula or a unit. Then converts the objects with Formula.fromSet or UnitSpec.fromSet.
+  - [X] Create method loadFormulaElements( List<Object> elements). Tipically receives the list from parseCorpusElements(). It loads the units first, then the formulas, to avoid missing dependencies.
+  - [X] Change createDefaultCorpus to use loadFormulaElements instead of loadUnits and loadFormula. Make loadUnits and loadFormula private.
 - [ ] Use a single table in database `FORMULAELEMENT` to store formulas and units. The table contains only two columns: autonumeric id and text.
 - [ ] Create Formula.toStringLiteral. It is the reverse of Formula.fromSet( Formula.fromArrayStringLiteral(string)[0] )
 - [ ] Create UnitSpec.toStringLiteral, like Formula.toStringLiteral

lib/corpus.dart

@@ -180,5 +180,28 @@ class Corpus{
 
   Iterable<UnitSpec> allUnits() => _allUnits.values;
 
+  /// Loads formula elements, making sure to load units first, then formulas
+  /// to avoid dependency issues.
+  void loadFormulaElements(List<Object> elements) {
+    List<UnitSpec> units = [];
+    List<Formula> formulas = [];
+
+    // Separate units and formulas
+    for (final element in elements) {
+      if (element is UnitSpec) {
+        units.add(element);
+      } else if (element is Formula) {
+        formulas.add(element);
+      } else {
+        throw ArgumentError('Element must be either UnitSpec or Formula: $element');
+      }
+    }
+
+    // Load units first to satisfy dependencies
+    loadUnits(units);
+
+    // Then load formulas
+    loadFormulas(formulas);
+  }
 
 }

lib/defaults/default_corpus.dart

@@ -39,7 +39,7 @@ Future<Corpus> createDefaultCorpus() async{
       print( "Loading units from $unitRes");
       final literal = await loadResourceAsString(unitRes);
       final units = UnitSpec.fromArrayStringLiteral(literal);
-      corpus.loadUnits(units);
+      corpus.loadFormulaElements(units);
     }
   }
 
@@ -49,7 +49,7 @@ Future<Corpus> createDefaultCorpus() async{
     for (final formRes in formulaResources) {
       final literal = await loadResourceAsString(formRes);
       final formulas = Formula.fromArrayStringLiteral(literal);
-      corpus.loadFormulas(formulas);
+      corpus.loadFormulaElements(formulas);
     }
   }
 

lib/formula_models.dart

@@ -23,6 +23,47 @@ abstract class SetUtils {
   }
 }
 
+/// Parses a d4rt array literal (containing maps and arrays) to a List<Object?>
+/// using d4rt
+List<Object?> parseD4rtLiteral(String arrayStringLiteral) {
+  var d4rt = D4rt();
+  final buffer = StringBuffer();
+  buffer.write("main(){ return $arrayStringLiteral; }");
+  final code = buffer.toString();
+
+  final List<Object?> list = d4rt.execute(source: code);
+
+  return list;
+}
+
+/// 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) {
+  final List<Object?> elements = parseD4rtLiteral(arrayStringLiteral);
+  
+  final List<Object> 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');
+      }
+    } else {
+      throw ArgumentError('Element must be a Map: $element');
+    }
+  }
+  
+  return result;
+}
+
 typedef Number = double;
 
 
@@ -86,12 +127,7 @@ class UnitSpec {
   }
 
   static List<UnitSpec> fromArrayStringLiteral(String arrayStringLiteral) {
-    var d4rt = D4rt();
-    final buffer = StringBuffer();
-    buffer.write("main(){ return $arrayStringLiteral; }");
-    final code = buffer.toString();
-
-    final List<Object?> list = d4rt.execute(source: code);
+    final List<Object?> list = parseD4rtLiteral(arrayStringLiteral);
 
     final units = list.map((set) => UnitSpec.fromSet(set as Map));
 
@@ -195,13 +231,7 @@ class Formula {
   }
 
   static List<Formula> fromArrayStringLiteral(String arrayStringLiteral) {
-    var d4rt = D4rt();
-    final buffer = StringBuffer();
-    buffer.write("main(){ return $arrayStringLiteral; }");
-    final code = buffer.toString();
-
-    //print("fromArrayStringLiteral:$code");
-    final List<Object?> list = d4rt.execute(source: code);
+    final List<Object?> list = parseD4rtLiteral(arrayStringLiteral);
 
     final formulas = list.map((set) => Formula.fromSet(set as Map));