switch_vs_if_else

main.dart

import 'dart:math';

/// A small test to test the performance of
/// `if-else` statements to `switch-case` statements.
///
/// The same [Stopwatch] and [Random] are use for the entire test.
/// Each one-to-one execution of a test (5 in total) uses a new list of
/// random values to iterate through to create identical scenarios.
///
///
/// Compiled
/// ```
/// $ dart compile exe main.dart && ./main.exe
/// ```
///
/// JIT
/// ```
/// $ dart run main.dart
/// ```
void main() {
  final iterations = 5;
  final random = Random();
  final stopwatch = Stopwatch();
  final results = Iterable.generate(
    iterations,
    (index) {
      return runner(
          stopwatch,
          Iterable.generate(
            10000000,
            (_) => Option.values[random.nextInt(3)],
          ));
    },
  ).fold<TestResult>(
    const TestResult(0, 0),
    (prev, current) => prev + current,
  );
  print(results.toString());
}

enum Option { one, two, three } // arbitrary object

class TestResult {
  const TestResult(this.switchTime, this.ifElseTime);
  final int switchTime;
  final int ifElseTime;

  operator +(TestResult other) =>
      TestResult(other.switchTime + switchTime, other.ifElseTime + ifElseTime);

  @override
  String toString() => '''
TestResult(
  switch : ${switchTime}ms
  if-else: ${ifElseTime}ms
)
''';
}

TestResult runner(
  Stopwatch stopwatch,
  Iterable<Option> listOfOptions,
) {
  final ones = <Option>{};
  final twos = <Option>{};
  final threes = <Option>{};

  void tearDown() {
    ones.clear();
    twos.clear();
    threes.clear();
    stopwatch.reset();
  }

  stopwatch.start();
  for (final option in listOfOptions) {
    if (option == Option.one) {
      ones.add(option);
    } else if (option == Option.two) {
      twos.add(option);
    } else if (option == Option.three) {
      threes.add(option);
    }
  }
  stopwatch.stop();
  final ifElseTime = stopwatch.elapsedMilliseconds;
  tearDown();

  stopwatch.start();
  for (final option in listOfOptions) {
    switch (option) {
      case Option.one:
        ones.add(option);
        break;
      case Option.two:
        twos.add(option);
        break;
      case Option.three:
        threes.add(option);
        break;
    }
  }
  stopwatch.stop();
  final switchTime = stopwatch.elapsedMilliseconds;
  tearDown();

  return TestResult(switchTime, ifElseTime);
}

/// System
/// ```
/// $ dart --version
/// > Dart SDK version: 2.17.1 (stable) (Tue May 17 17:58:21 2022 +0000) on "macos_x64"
/// ```

/// Results:
/// ```
/// $ dart compile exe main.dart && ./main.exe
/// > TestResult(
/// >   switch : 1770ms
/// >   if-else: 1815ms
/// > )
/// ```
/// ```
/// $ dart run main.dart
/// > TestResult(
/// >   switch : 1945ms
/// >   if-else: 1831ms
/// > )
/// ```