feat: use Math namespace for pow function in formulas

lib/defaults/formulas.d4rt

@@ -17,7 +17,7 @@ Where:
       {"name": "g", "unit": "meters per second"}  // Gravitational acceleration
     ],
     "output": {"name": "h", "unit": "meter"},  // Height in meters
-    "d4rtCode": "h = 0.5 * g * pow(t, 2);",
+    "d4rtCode": "h = 0.5 * g * Math.pow(t, 2);",
     "tags": ["physics", "kinematics"]
   },
   
@@ -41,7 +41,7 @@ Where:
       {"name": "r", "unit": "meter"}     // Distance between masses
     ],
     "output": {"name": "F", "unit": "newton"},  // Force in newtons
-    "d4rtCode": "F = (6.67430e-11 * m1 * m2) / pow(r, 2);",
+    "d4rtCode": "F = (6.67430e-11 * m1 * m2) / Math.pow(r, 2);",
     "tags": ["physics", "astronomy", "gravity"]
   },
   
@@ -63,7 +63,7 @@ Where:
       {"name": "v", "unit": "meters per second"}  // Velocity
     ],
     "output": {"name": "KE", "unit": "joule"},  // Energy in joules
-    "d4rtCode": "KE = 0.5 * m * pow(v, 2);",
+    "d4rtCode": "KE = 0.5 * m * Math.pow(v, 2);",
     "tags": ["physics", "energy", "mechanics"]
   },
   
@@ -82,7 +82,7 @@ Where:
       {"name": "θ", "unit": "degree"}   // Launch angle
     ],
     "output": {"name": "R", "unit": "meter"},  // Horizontal distance
-    "d4rtCode": "R = (pow(v, 2) * sin(2 * radians(θ))) / 9.80665;",
+    "d4rtCode": "R = (Math.pow(v, 2) * sin(2 * radians(θ))) / 9.80665;",
     "tags": ["physics", "kinematics", "projectile"]
   },
 

lib/formula_evaluator.dart

@@ -1,7 +1,13 @@
+import 'dart:math' as Math;
 
 import 'package:d4rt/d4rt.dart';
 import 'formula_models.dart';
 
+
+
+
+
+
 /// Exception thrown when formula evaluation fails
 class FormulaEvaluationException implements Exception {
   final String message;
@@ -14,34 +20,39 @@ class FormulaEvaluationException implements Exception {
       '${cause != null ? ' (caused by: $cause)' : ''}';
 }
 
-/// Evaluates formulas using the d4rt interpreter
+class MyMath{
+  static Number log(Number x) => Math.log(x);
+  static Number pow(Number b, Number e) => Math.pow(b,e) as Number;
+}
+
 class FormulaEvaluator {
   final D4rt _interpreter;
 
-  /// Creates a new formula evaluator with an optional d4rt interpreter instance.
-  /// If no interpreter is provided, a new one will be created.
-  FormulaEvaluator([D4rt? interpreter]) : _interpreter = interpreter ?? D4rt();
+  FormulaEvaluator([D4rt? interpreter]) : _interpreter = interpreter ?? D4rt(){
+    prepareInterpreter(_interpreter);
+  }
 
-  /// Evaluates a formula with the given input values.
-  /// 
-  /// The [formula] must have exactly one output variable (validated during construction).
-  /// The [inputValues] map must contain values for all input variables defined
-  /// in the formula.
-  /// 
-  /// The formula's d4rt_code should define a main function that uses the input
-  /// variable names directly. The evaluator will inject variable declarations
-  /// before the formula code. For example:
-  /// ```
-  /// main() {
-  ///   return m * a;  // Returns Force = mass * acceleration
-  /// }
-  /// ```
-  /// 
-  /// Returns the computed value of the single output variable.
-  /// 
-  /// Throws [FormulaEvaluationException] if:
-  /// - Required input variables are missing
-  /// - The d4rt code execution fails
+  Number getNumberValueOf(String s){
+    return double.parse(s);
+  }
+
+  void prepareInterpreter(D4rt interpreter){
+    final myMathDefinition = BridgedClass(
+      nativeType: MyMath,
+      name: 'Math',
+      staticMethods: {
+        'pow': (visitor, positionalArgs, namedArgs) {
+          final Number base = getNumberValueOf( positionalArgs[0].toString() );
+          final Number exp = getNumberValueOf( positionalArgs[1].toString() );
+          return MyMath.pow(base,exp);
+        },
+      }
+    );
+    
+    interpreter.registerBridgedClass(myMathDefinition, 'package:myapp/my_math.dart');
+  }
+
+  
   dynamic evaluate(Formula formula, Map<String, dynamic> inputValues) {
     _validateInputValues(formula, inputValues);
 
@@ -61,7 +72,6 @@ class FormulaEvaluator {
     }
   }
 
-  /// Validates that all required input variables are provided
   void _validateInputValues(Formula formula, Map<String, dynamic> inputValues) {
     final missingVars = <String>[];
     
@@ -79,47 +89,37 @@ class FormulaEvaluator {
     }
   }
 
-  /// Gets the name of the single output variable from the formula
   String getOutputVariableName(Formula formula) {
     return formula.output.name;
   }
 
-  /// Gets the magnitude of the single output variable from the formula
   String getOutputVariableMagnitude(Formula formula) {
-    // Formula construction already ensures exactly one output variable
     return formula.output.unit;
   }
 
-  /// Gets the ordered list of input variable names (alphabetically sorted)
   List<String> getInputVariableOrder(Formula formula) {
     return formula.inputVarNames()..sort();
   }
 
-  /// Builds the complete d4rt source code by injecting variable declarations
-  /// before the formula's d4rt code
   String _buildCompleteSource(Formula formula, Map<String, dynamic> inputValues) {
     final buffer = StringBuffer();
 
+    buffer.writeln("import 'package:myapp/my_math.dart';");
     buffer.writeln("main(){");
 
-    // Add variable declarations for all input variables
     for (final entry in inputValues.entries) {
       final varName = entry.key;
       final value = entry.value;
       
-      // Handle different value types appropriately for d4rt
       if (value is String) {
-        // Escape quotes in string values
         final escapedValue = value.replaceAll('"', '\\"');
         buffer.writeln('var $varName = "$escapedValue";');
       } else {
-        // For numbers and other types, use direct representation
         buffer.writeln('var $varName = $value;');
       }
     }
     buffer.writeln("late var ${getOutputVariableName(formula)};");
     
-    // Add the formula's d4rt code
     buffer.writeln(formula.d4rtCode);
     buffer.writeln("return ${getOutputVariableName(formula)};");
     buffer.writeln("}");