key-sort-bench.dart

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

void main() {
  var keyFn = (n) {
        var sum = n % 9;
        if (sum == 0 && n > 0) sum = 9;
        return sum;
      },
      compFn = (n1, n2) => keyFn(n1).compareTo(keyFn(n2));
  Random rand = new Random();

  double  totalKeySortScore = .0,
          totalCompSortScore = .0;
  
  for (int i = 0; i < 10; i++) {
    List list = new List.generate(1000, (_) => rand.nextInt(1000000), growable: false);
    print("Run $i with list: $list");
    
    var keySortBench = new KeySortBenchmark(new List.from(list, growable: false), keyFn),
        compSortBench = new CompSortBenchmark(new List.from(list, growable: false), compFn);
    double  keySortScore = keySortBench.measure(),
            compSortScore = compSortBench.measure();
    
    totalKeySortScore += keySortScore;
    totalCompSortScore += compSortScore;
    
    print("KeySort scored $keySortScore. Result: ${keySortBench.list}");
    print("CompSort scored $compSortScore. Result: ${compSortBench.list}");
    
    print("\n");
  }
  print("Total scores: KeySort - $totalKeySortScore | CompSort - $totalCompSortScore");
}

class KeySortBenchmark extends BenchmarkBase {
  
  List list;
  var fn;

  KeySortBenchmark(this.list, this.fn) : super('KeySortBenchmark');

  run() {
    new KeySorter(list).sort(fn);
  }

}

class CompSortBenchmark extends BenchmarkBase {

  List list;
  var fn;

  CompSortBenchmark(this.list, this.fn) : super('CompSortBenchmark');

  run() {
    list.sort(fn);
  }

}

class KeySorter<V, K extends Comparable> {

  List<V> list;

  KeySorter(this.list);
  
  List<V> sort(K keyFn(V)) {
    Map<V, K> keys = {};
    list.sort((e1, e2) {
      var e1Key = keys.putIfAbsent(e1, () => keyFn(e1)),
          e2Key = keys.putIfAbsent(e2, () => keyFn(e2));
      return e1Key.compareTo(e2Key);
    });
    
    return list;
  }
}