int extension

lib/src/int_extensions.dart

@@ -0,0 +1,40 @@
+/// Extensions that apply to all integers.
+///
+/// These extensions provide some generally useful convenience methods.
+/// Credits to supercharged_dart
+extension IntRange on int {
+  /// Creates an [Iterable<int>] that contains all values from current integer
+  /// until (including) the value [n].
+  ///
+  /// Example:
+  /// ```dart
+  /// 0.rangeTo(5); // [0, 1, 2, 3, 4, 5]
+  /// 3.rangeTo(1); // [3, 2, 1]
+  /// ```
+  Iterable<int> rangeTo(int n) {
+    final count = (n - this).abs() + 1;
+    final direction = (n - this).sign;
+    var i = this - direction;
+    return Iterable.generate(count, (index) {
+      return i += direction;
+    });
+  }
+
+  /// Creates an [Iterable<int>] that contains all values from current integer
+  /// until (excluding) the value [n].
+  ///
+  /// Example:
+  /// ```dart
+  /// 0.until(5); // [0, 1, 2, 3, 4]
+  /// 3.until(1); // [3, 2]
+  /// ```
+  Iterable<int> until(int n) {
+    if (this < n) {
+      return rangeTo(n - 1);
+    } else if (this > n) {
+      return rangeTo(n + 1);
+    } else {
+      return Iterable.empty();
+    }
+  }
+}

test/extensions_test.dart

@@ -5,9 +5,34 @@
 import 'dart:math' show pow, Random;
 
 import 'package:collection/collection.dart';
+import 'package:collection/src/int_extensions.dart';
 import 'package:test/test.dart';
 
 void main() {
+  group('int', () {
+    group('.until', () {
+      test('increase', () {
+        expect(1.until(5), iterable([1, 2, 3, 4]));
+      });
+      test('decrease', () {
+        expect(5.until(1), iterable([5, 4, 3, 2]));
+      });
+      test('same', () {
+        expect(1.until(1), Iterable.empty());
+      });
+    });
+    group('.rangeTo', () {
+      test('increase', () {
+        expect(1.rangeTo(5), iterable([1, 2, 3, 4, 5]));
+      });
+      test('decrease', () {
+        expect(5.rangeTo(1), iterable([5, 4, 3, 2, 1]));
+      });
+      test('same', () {
+        expect(1.rangeTo(1), iterable([1]));
+      });
+    });
+  });
   group('Iterable', () {
     group('of any', () {
       group('.whereNot', () {