Compass app (#2446)

compass_app/app/lib/utils/result.dart

@@ -0,0 +1,54 @@
+// Copyright 2024 The Flutter team. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+/// Utility class to wrap result data
+///
+/// Evaluate the result using a switch statement:
+/// ```dart
+/// switch (result) {
+///   case Ok(): {
+///     print(result.value);
+///   }
+///   case Error(): {
+///     print(result.error);
+///   }
+/// }
+/// ```
+sealed class Result<T> {
+  const Result();
+
+  /// Creates an instance of Result containing a value
+  factory Result.ok(T value) => Ok(value);
+
+  /// Create an instance of Result containing an error
+  factory Result.error(Exception error) => Error(error);
+
+  /// Convenience method to cast to Ok
+  Ok<T> get asOk => this as Ok<T>;
+
+  /// Convenience method to cast to Error
+  Error get asError => this as Error<T>;
+}
+
+/// Subclass of Result for values
+final class Ok<T> extends Result<T> {
+  const Ok(this.value);
+
+  /// Returned value in result
+  final T value;
+
+  @override
+  String toString() => 'Result<$T>.ok($value)';
+}
+
+/// Subclass of Result for errors
+final class Error<T> extends Result<T> {
+  const Error(this.error);
+
+  /// Returned error in result
+  final Exception error;
+
+  @override
+  String toString() => 'Result<$T>.error($error)';
+}