Enum utils

benchmark.dart

import 'package:benchmark_harness/benchmark_harness.dart';

void main() {
  final letter = Example.values[25];
  final simple = Simple(letter).measure();
  final cache = Cache(letter).measure();
  print('$simple / $cache = ${simple / cache}'); // 4.074025631823892
}

enum Example {
  a,
  b,
  c,
  d,
  e,
  f,
  g,
  h,
  i,
  j,
  k,
  l,
  m,
  n,
  o,
  p,
  q,
  r,
  s,
  t,
  u,
  v,
  w,
  x,
  y,
  z
}

class Simple extends BenchmarkBase {
  Simple([this.letter = Example.g])
      : name = letter.name,
        super('Simple');

  final Example letter;
  final String name;

  @override
  void run() {
    final result = Example.values.firstWhere((element) => element.name == name);
    if (result != letter) throw Exception('Error');
  }
}

class Cache extends BenchmarkBase {
  Cache([this.letter = Example.g])
      : name = letter.name,
        super('Cache');

  final Example letter;
  final String name;

  @override
  void run() {
    final result = EnumUtil.search(Example.values, name);
    if (result != letter) throw Exception('Error');
  }
}

abstract final class EnumUtil {
  static final Map<int, Map<String, Enum>> _$searchCache = {};
  static Never _$searchNotFound() => throw Exception('Not found');
  static T search<T extends Enum>(
    Iterable<T> values,
    Object? /* String | int */ value, {
    T Function()? fallback,
  }) {
    if (value is String) {
      final cache = _$searchCache.putIfAbsent(
          values.hashCode, () => {for (final e in values) e.name: e});
      if (cache[value] case T result) return result;
    } else if (value is int) {
      try {
        return values.elementAt(value);
      } on RangeError {/* ignore */}
    }
    return fallback?.call() ?? _$searchNotFound();
  }
}

main.dart

void main() {
  print(EnumUtil.search(Example.values, 'a'));
  print(EnumUtil.search(Example.values, 1));
  print(EnumUtil.search(Example.values, 'z', fallback: () => Example.c));
}

enum Example { a, b, c }

abstract final class EnumUtil {
  static final Map<int, Map<String, Enum>> _$searchCache = {};
  static Never _$searchNotFound() => throw Exception('Not found');
  static T search<T extends Enum>(
    Iterable<T> values,
    Object? /* String | int */ value, {
    T Function()? fallback,
  }) {
    if (value is String) {
      final cache = _$searchCache.putIfAbsent(
          values.hashCode, () => {for (final e in values) e.name: e});
      if (cache[value] case T e) return e;
    } else if (value is int) {
      try {
        return values.elementAt(value);
      } on RangeError {/* ignore */}
    }
    return fallback?.call() ?? _$searchNotFound();
  }
}