Merge pull request #16 from kranfix/option_utils

Option and Result extensions

lib/oxidized.dart

@@ -94,3 +94,6 @@ library oxidized;
 export 'src/option.dart';
 export 'src/result.dart';
 export 'src/unit.dart';
+
+export 'src/option_utils/option_utils.dart';
+export 'src/result_utils/result_utils.dart';

lib/src/option_utils/option_option_flattener.dart

@@ -0,0 +1,20 @@
+part of 'option_utils.dart';
+
+extension OptionOptionFlattener<T extends Object> on Option<Option<T>> {
+  /// Flats an option of an option.
+  ///
+  /// ```dart
+  /// Some(Some(1)) => Some(1)
+  /// Some(None()) => None()
+  /// None() => None()
+  /// ```
+  ///
+  /// See also:
+  /// - https://doc.rust-lang.org/std/option/enum.Option.html#method.flatten
+  Option<T> flatten() {
+    return match(
+      (option) => option,
+      () => None(),
+    );
+  }
+}

lib/src/option_utils/option_result_transposer.dart

@@ -0,0 +1,23 @@
+part of 'option_utils.dart';
+
+extension OptionResultTransposer<T extends Object, E extends Object>
+    on Option<Result<T, E>> {
+  /// Transposes the result of an option.
+  ///
+  /// ```dart
+  /// Some(Ok(1)) => Ok(Some(1));
+  /// Some(Err('error message')) => Err('error message');
+  /// None() => Ok(None());
+  /// ```
+  ///
+  /// See also https://doc.rust-lang.org/std/option/enum.Option.html#method.transpose
+  Result<Option<T>, E> transpose() {
+    return match(
+      (result) => result.match(
+        (value) => Ok(Some(value)),
+        (err) => Err(err),
+      ),
+      () => Ok(None()),
+    );
+  }
+}

lib/src/option_utils/option_utils.dart

@@ -0,0 +1,4 @@
+import 'package:oxidized/oxidized.dart';
+
+part 'option_option_flattener.dart';
+part 'option_result_transposer.dart';

lib/src/result_utils/result_option_transposer.dart

@@ -0,0 +1,24 @@
+part of 'result_utils.dart';
+
+extension ResultOptionTransposer<T extends Object, E extends Object>
+    on Result<Option<T>, E> {
+  /// Transposes the result to an option.
+  ///
+  /// ```dart
+  /// Ok(None()) => None()
+  /// Ok(Some(val)) => Some(Ok(val))
+  /// Err(err) => Some(Err(err))
+  /// ```
+  ///
+  /// See also:
+  /// - https://doc.rust-lang.org/std/result/enum.Result.html#method.transpose
+  Option<Result<T, E>> transpose() {
+    return match(
+      (option) => option.match(
+        (val) => Some(Ok(val)),
+        () => None(),
+      ),
+      (err) => Some(Err(err)),
+    );
+  }
+}

lib/src/result_utils/result_result_flattener.dart

@@ -0,0 +1,24 @@
+part of 'result_utils.dart';
+
+extension ResultResultFlattener<T extends Object, E extends Object>
+    on Result<Result<T, E>, E> {
+  /// Flattens a [Result<Result<T, E>, E>] into a [Result<T, E>]
+  ///
+  /// ```dart
+  /// Ok(Ok(value)) => Ok(value)
+  /// Ok(Err(error)) => Err(error)
+  /// Err(error) => Err(error)
+  /// ```
+  ///
+  /// See also:
+  /// - https://doc.rust-lang.org/std/result/enum.Result.html#method.flatten
+  Result<T, E> flatten() {
+    return match(
+      (result) => result.match(
+        (val) => Ok(val),
+        (err) => Err(err),
+      ),
+      (err) => Err(err),
+    );
+  }
+}

lib/src/result_utils/result_utils.dart

@@ -0,0 +1,4 @@
+import 'package:oxidized/oxidized.dart';
+
+part 'result_option_transposer.dart';
+part 'result_result_flattener.dart';

pubspec.yaml

@@ -6,7 +6,7 @@ repository: https://github.com/nlfiedler/oxidized.git
 issue_tracker: https://github.com/nlfiedler/oxidized/issues
 
 environment:
-  sdk: '>=2.12.0 <3.0.0'
+  sdk: ">=2.13.0 <3.0.0"
 
 dependencies:
   equatable: ^2.0.3

test/src/option_utils/option_option_flattener_test.dart

@@ -0,0 +1,25 @@
+import 'package:oxidized/oxidized.dart';
+import 'package:test/test.dart';
+
+typedef OptInt = Option<int>;
+typedef OptOptInt = Option<OptInt>;
+
+void main() {
+  test('None().flatten() must return None', () {
+    final OptOptInt input = None();
+    final OptInt output = None();
+    expect(input.flatten(), equals(output));
+  });
+
+  test('Some(None()).flatten() must return None()', () {
+    final OptOptInt input = Some(None());
+    final OptInt output = None();
+    expect(input.flatten(), equals(output));
+  });
+
+  test('Some(Some(val)).flatten() must return Some(val)', () {
+    final OptOptInt input = Some(Some(1));
+    final OptInt output = Some(1);
+    expect(input.flatten(), equals(output));
+  });
+}

test/src/option_utils/option_result_transposer_test.dart

@@ -0,0 +1,25 @@
+import 'package:oxidized/oxidized.dart';
+import 'package:test/test.dart';
+
+typedef OptRes = Option<Result<int, String>>;
+typedef ResOpt = Result<Option<int>, String>;
+
+void main() {
+  test('None() transpose must return Ok(None())', () {
+    final OptRes input = None();
+    final ResOpt output = Ok(None());
+    expect(input.transpose(), equals(output));
+  });
+
+  test('Some(Ok(val)) transpose must return Ok(Some(val))', () {
+    final OptRes input = Some(Ok(1));
+    final ResOpt output = Ok(Some(1));
+    expect(input.transpose(), equals(output));
+  });
+
+  test('Some(Err(val)) transpose must return Err(val)', () {
+    final OptRes input = Some(Err('error'));
+    final ResOpt output = Err('error');
+    expect(input.transpose(), equals(output));
+  });
+}

test/src/result_utils/result_option_transposer_test.dart

@@ -0,0 +1,25 @@
+import 'package:oxidized/oxidized.dart';
+import 'package:test/test.dart';
+
+typedef OptRes = Option<Result<int, String>>;
+typedef ResOpt = Result<Option<int>, String>;
+
+void main() {
+  test('Ok(None()).transpose() must return None()', () async {
+    final ResOpt input = Ok(None());
+    final OptRes output = None();
+    expect(input.transpose(), output);
+  });
+
+  test('Ok(Some(val)).transpose() must return Some(Ok(val))', () async {
+    final ResOpt input = Ok(Some(1));
+    final OptRes output = Some(Ok(1));
+    expect(input.transpose(), output);
+  });
+
+  test('Err(err).transpose() must return Some(Err(err))', () async {
+    final ResOpt input = Err('error message');
+    final OptRes output = Some(Err('error message'));
+    expect(input.transpose(), output);
+  });
+}

test/src/result_utils/result_result_flattener_test.dart

@@ -0,0 +1,25 @@
+import 'package:oxidized/oxidized.dart';
+import 'package:test/test.dart';
+
+typedef Res = Result<int, String>;
+typedef ResRes = Result<Result<int, String>, String>;
+
+void main() {
+  test('Ok(Ok(val).flatten() must return Ok(val)', () async {
+    final ResRes input = Ok(Ok(1));
+    final Res output = Ok(1);
+    expect(input.flatten(), output);
+  });
+
+  test('Ok(Err(err).flatten() must return Err(err)', () async {
+    final ResRes input = Ok(Err('error message'));
+    final Res output = Err('error message');
+    expect(input.flatten(), output);
+  });
+
+  test('Err(err).flatten() must return Err(err)', () async {
+    final ResRes input = Err('error message');
+    final Res output = Err('error message');
+    expect(input.flatten(), output);
+  });
+}