parseSimpleOperation function

TSimpleOperation? parseSimpleOperation(String expression)

Parses a simple mathematical operation expression and returns a TSimpleOperation object that represents the operation.

The expression parameter is a string that represents the mathematical operation in the format of "operand operator operand = result", where operand is a number (positive or negative), operator is a mathematical operator (+, -, *, /, ×, or ÷), and result is an optional number that represents the result of the operation.

This function only supports simple operations with two operands and one operator. If the input expression is not in the expected format, or if the operands or operator are not valid, the function returns null.

Returns a TSimpleOperation object that represents the operation.

Implementation

TSimpleOperation? parseSimpleOperation(String expression) {
  // Define a regular expression called `pattern` that matches the format of
  // "operand operator operand = result".
  final pattern = RegExp(
      r'^\s*(-?\d+(?:\.\d+)?)\s*([+\-*/×÷])\s*(-?\d+(?:\.\d+)?)(?:\s*=\s*(-?\d+(?:\.\d+)?))?\s*$');

  // Use the `firstMatch` method of the `RegExp` class to extract the operands,
  // operator, and result from the `expression` string.
  final match = pattern.firstMatch(expression);

  if (match == null) {
    // Return null if the expression doesn't match the expected format.
    return null;
  }

  // Extract the operands, operator, and result from the `Match` object.
  final operand1 = match.group(1);
  final operator = match.group(2);
  final operand2 = match.group(3);
  final result = match.group(4);

  if (operand1 == null || operator == null || operand2 == null) {
    // Return null if any of the operands or operator is null.
    return null;
  }

  return TSimpleOperation(
    operands: [operand1, operand2],
    operator: operator,
    result: result,
  );
}