Various string benchmarks in Dart

string_benchmark.dart

import 'dart:math';

import 'package:benchmark_harness/benchmark_harness.dart';
import 'package:characters/characters.dart';

const String _kCharset =
    'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
final Random _random = Random();

String _generateRandomString(int length) {
  return String.fromCharCodes(
    List.generate(
      length,
      growable: false,
      (_) => _kCharset.codeUnitAt(_random.nextInt(_kCharset.length)),
    ),
  );
}

final _randomString = _generateRandomString(256);

final class StringForBenchmark extends BenchmarkBase {
  StringForBenchmark() : super('StringForBenchmark');

  List<String> _chars = [];

  @override
  void warmup() {
    for (var i = 0; i < 50; i++) {
      _chars = [];
      run();
    }
  }

  @override
  void run() {
    for (int i = 0; i < _randomString.length; i++) {
      _chars.add(_randomString[i]);
    }
  }

  // @override
  // void teardown() {
  //   print(_chars.length);
  //   super.teardown();
  // }

  @override
  void exercise() {
    for (var i = 0; i < 1000; i++) {
      _chars = [];
      run();
    }
  }
}

final class StringSplitBenchmark extends BenchmarkBase {
  StringSplitBenchmark() : super('StringSplitBenchmark');

  List<String> _chars = [];

  @override
  void warmup() {
    for (var i = 0; i < 50; i++) {
      _chars = [];
      run();
    }
  }

  @override
  void run() {
    for (final c in _randomString.split('')) {
      _chars.add(c);
    }
  }

  // @override
  // void teardown() {
  //   print(_chars.length);
  //   super.teardown();
  // }

  @override
  void exercise() {
    for (var i = 0; i < 1000; i++) {
      _chars = [];
      run();
    }
  }
}

final class CharactersBenchmark extends BenchmarkBase {
  CharactersBenchmark() : super('CharactersBenchmark');

  List<String> _chars = [];

  @override
  void warmup() {
    for (var i = 0; i < 50; i++) {
      _chars = [];
      run();
    }
  }

  @override
  void run() {
    for (final c in _randomString.characters) {
      _chars.add(c);
    }
  }

  // @override
  // void teardown() {
  //   print(_chars.length);
  //   super.teardown();
  // }

  @override
  void exercise() {
    for (var i = 0; i < 1000; i++) {
      _chars = [];
      run();
    }
  }
}

final class CodeUnitsBenchmark extends BenchmarkBase {
  CodeUnitsBenchmark() : super('CodeUnitsBenchmark');

  List<String> _chars = [];

  @override
  void warmup() {
    for (var i = 0; i < 50; i++) {
      _chars = [];
      run();
    }
  }

  @override
  void run() {
    for (final cu in _randomString.codeUnits) {
      _chars.add(String.fromCharCode(cu));
    }
  }

  // @override
  // void teardown() {
  //   print(_chars.length);
  //   super.teardown();
  // }

  @override
  void exercise() {
    for (var i = 0; i < 1000; i++) {
      _chars = [];
      run();
    }
  }
}

final class SyncStarBenchmark extends BenchmarkBase {
  SyncStarBenchmark() : super('SyncStarBenchmark');

  List<String> _chars = [];

  @override
  void warmup() {
    for (var i = 0; i < 50; i++) {
      _chars = [];
      run();
    }
  }

  @override
  void run() {
    for (final c in _randomString.chars) {
      _chars.add(c);
    }
  }

  // @override
  // void teardown() {
  //   print(_chars.length);
  //   super.teardown();
  // }

  @override
  void exercise() {
    for (var i = 0; i < 1000; i++) {
      _chars = [];
      run();
    }
  }
}

final class CustomIterableBenchmark extends BenchmarkBase {
  CustomIterableBenchmark() : super('CustomIterableBenchmark');

  List<String> _chars = [];

  @override
  void warmup() {
    for (var i = 0; i < 50; i++) {
      _chars = [];
      run();
    }
  }

  @override
  void run() {
    for (final c in _randomString.asIterable) {
      _chars.add(c);
    }
  }

  // @override
  // void teardown() {
  //   print(_chars.length);
  //   super.teardown();
  // }

  @override
  void exercise() {
    for (var i = 0; i < 1000; i++) {
      _chars = [];
      run();
    }
  }
}

extension on String {
  Iterable<String> get chars sync* {
    for (var i = 0; i < length; i++) {
      yield this[i];
    }
  }

  Iterable<String> get asIterable => CustomStringIterable(this);
}

final class CustomStringIterable extends Iterable<String> {
  const CustomStringIterable(this._string);

  final String _string;

  @override
  int get length => _string.length;

  @override
  String elementAt(int index) => _string[index];

  @override
  Iterator<String> get iterator => CustomStringIterator(_string);
}

final class CustomStringIterator implements Iterator<String> {
  CustomStringIterator(this._str);

  final String _str;

  int _idx = -1;

  @override
  String get current => _str[_idx];

  @override
  bool moveNext() => ++_idx < _str.length;
}

void main() {
  StringForBenchmark().report();
  StringSplitBenchmark().report();
  CharactersBenchmark().report();
  CodeUnitsBenchmark().report();
  SyncStarBenchmark().report();
  CustomIterableBenchmark().report();
}