71 lines
1.6 KiB
Dart
71 lines
1.6 KiB
Dart
/// Utility class that simplifies handling errors.
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///
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/// Return a [Result] from a function to indicate success or failure.
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///
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/// A [Result] is either an [Ok] with a value of type [T]
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/// or an [Err] with an [Exception].
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///
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/// Use [Result.ok] to create a successful result with a value of type [T].
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/// Use [Result.error] to create an error result with an [Exception].
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///
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/// Evaluate the result using a switch statement:
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/// ```dart
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/// switch (result) {
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/// case Ok(): {
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/// print(result.value);
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/// }
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/// case Error(): {
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/// print(result.error);
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/// }
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/// }
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/// ```
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sealed class Result<T> {
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const Result();
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/// Creates a successful [Result], completed with the specified [value].
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const factory Result.ok(T value) = Ok._;
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/// Creates an error [Result], completed with the specified [error].
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const factory Result.error(Exception error) = Err._;
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bool isOk() {
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return this is Ok;
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}
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T value() {
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Ok<T> ok = this as Ok<T>;
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return ok._value;
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}
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bool isErr() {
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return this is Err;
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}
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Exception error() {
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Err<T> err = this as Err<T>;
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return err._error;
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}
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}
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/// A successful [Result] with a returned [value].
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final class Ok<T> extends Result<T> {
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const Ok._(this._value);
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/// The returned value of this result.
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final T _value;
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@override
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String toString() => 'Result<$T>.ok($_value)';
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}
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/// An error [Result] with a resulting [error].
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final class Err<T> extends Result<T> {
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const Err._(this._error);
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/// The resulting error of this result.
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final Exception _error;
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@override
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String toString() => 'Result<$T>.error($_error)';
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}
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