Serena

import 'helper.dart'; /// Main calculator class demonstrating various Dart features class Calculator { /// Private field for storing history final List<String> _history = []; /// Getter for accessing calculation history List<String> get history => List.unmodifiable(_history); /// Adds two integers and records the operation int add(int a, int b) { final result = a + b; _history.add('$a + $b = $result'); return result; } /// Subtracts two integers using the helper function int performSubtract(int a, int b) { final result = subtract(a, b); // Reference to imported function _history.add('$a - $b = $result'); return result; } /// Multiplies two numbers using helper class double performMultiply(double x, double y) { final result = multiply(x, y); // Reference to imported function _history.add('$x * $y = $result'); return result; } /// Divides two numbers with error handling double divide(double dividend, double divisor) { if (divisor == 0) { throw ArgumentError('Division by zero is not allowed'); } final result = dividend / divisor; _history.add('$dividend / $divisor = $result'); return result; } /// Clears the calculation history void clearHistory() { _history.clear(); } /// Performs a complex calculation using multiple operations double complexCalculation(double a, double b, double c) { final step1 = add(a.toInt(), b.toInt()).toDouble(); // Reference to add method final step2 = MathHelper.power(step1, 2); // Reference to helper class method final result = step2 + c; _history.add('Complex: ($a + $b)^2 + $c = $result'); return result; } } /// A mixin for providing logging functionality mixin LoggerMixin { void log(String message) { print('[${DateTime.now()}] $message'); } } /// An abstract class for defining calculators abstract class CalculatorInterface { int add(int a, int b); int subtract(int a, int b); } /// Advanced calculator that extends Calculator and uses mixin class AdvancedCalculator extends Calculator with LoggerMixin implements CalculatorInterface { /// Performs scientific calculation with logging double scientificOperation(Operation operation) { log('Performing ${operation.type} operation'); switch (operation.type) { case OperationType.addition: return operation.operand1 + operation.operand2; case OperationType.subtraction: return operation.operand1 - operation.operand2; case OperationType.multiplication: return operation.operand1 * operation.operand2; case OperationType.division: if (operation.operand2 == 0) { throw ArgumentError('Division by zero'); } return operation.operand1 / operation.operand2; } } /// Factory constructor for creating calculators factory AdvancedCalculator.withLogger() { return AdvancedCalculator(); } } /// Program entry point class Program { /// Main method demonstrating calculator usage static void main(List<String> args) { final calc = Calculator(); final result1 = calc.add(5, 3); // Reference to add method final result2 = calc.performSubtract(10, 4); // Reference to performSubtract method final result3 = calc.performMultiply(2.5, 4.0); // Reference to performMultiply method print('Addition result: $result1'); print('Subtraction result: $result2'); print('Multiplication result: $result3'); // Using advanced calculator final advancedCalc = AdvancedCalculator.withLogger(); final operation = ( type: OperationType.multiplication, operand1: 3.14, operand2: 2.0 ); final scientificResult = advancedCalc.scientificOperation(operation); print('Scientific result: $scientificResult'); // Display calculation history print('Calculation History:'); for (final entry in calc.history) { print(' $entry'); } } }