Implement getRange (returning an Iterable).

tests/corelib/list_get_range_test.dart

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import "package:expect/expect.dart";
 
-main() {
-  Expect.listEquals([], [].sublist(0, 0));
-  Expect.listEquals([], const [].sublist(0, 0));
+testGetRange(list, start, end, bool isModifiable) {
+  expectRE(() { list.getRange(-1, 0); });
+  expectRE(() { list.getRange(0, -1); });
+  expectRE(() { list.getRange(1, 0); });
+  expectRE(() { list.getRange(0, list.length + 1); });
+  expectRE(() { list.getRange(list.length + 1, list.length + 1); });
+  Iterable iterable = list.getRange(start, end);
+  Expect.isFalse(iterable is List);
+  if (start == end) {
+    Expect.isTrue(iterable.isEmpty);
+    return;
+  }
 
+  var iterator = iterable.iterator;
+  for (int i = start; i < end; i++) {
+    Expect.isTrue(iterator.moveNext());
+    Expect.equals(iterator.current, list[i]);
+  }
+  Expect.isFalse(iterator.moveNext());
 
-  Expect.listEquals([1, 2], [1, 2].sublist(0, 2));
-  Expect.listEquals([1, 2], const [1, 2].sublist(0, 2));
+  if (isModifiable) {
+    for (int i = 0; i < list.length; i++) {
+      list[i]++;
+    }
 
-  Expect.listEquals([1], [1, 2].sublist(0, 1));
-  Expect.listEquals([1], const [1, 2].sublist(0, 1));
-
-  Expect.listEquals([2], [1, 2].sublist(1, 2));
-  Expect.listEquals([2], const [1, 2].sublist(1, 2));
-
-  Expect.listEquals([], [1, 2].sublist(0, 0));
-  Expect.listEquals([], const [1, 2].sublist(0, 0));
-
-  Expect.listEquals([2, 3], [1, 2, 3, 4].sublist(1, 3));
-  Expect.listEquals([2, 3], const [1, 2, 3, 4].sublist(1, 3));
-
-  Expect.listEquals([2, 3], [1, 2, 3, 4].sublist(1, 3));
-  Expect.listEquals([2, 3], const [1, 2, 3, 4].sublist(1, 3));
-
-  expectAE(() => [].sublist(-1, null));
-  expectAE(() => const [].sublist(-1, null));
-  expectAE(() => [].sublist(-1, 0));
-  expectAE(() => const [].sublist(-1, 0));
-  expectAE(() => [].sublist(-1, -1));
-  expectAE(() => const [].sublist(-1, -1));
-  expectAE(() => [].sublist(-1, 1));
-  expectAE(() => const [].sublist(-1, 1));
-  expectAE(() => [].sublist(0, -1));
-  expectAE(() => const [].sublist(0, -1));
-  expectAE(() => [].sublist(0, 1));
-  expectAE(() => const [].sublist(0, 1));
-  expectAE(() => [].sublist(1, null));
-  expectAE(() => const [].sublist(1, null));
-  expectAE(() => [].sublist(1, 0));
-  expectAE(() => const [].sublist(1, 0));
-  expectAE(() => [].sublist(1, -1));
-  expectAE(() => const [].sublist(1, -1));
-  expectAE(() => [].sublist(1, 1));
-  expectAE(() => const [].sublist(1, 1));
-
-  expectAE(() => [1].sublist(0, 2));
-  expectAE(() => [1].sublist(1, 2));
-  expectAE(() => [1].sublist(1, 0));
+    iterator = iterable.iterator;
+    for (int i = start; i < end; i++) {
+      Expect.isTrue(iterator.moveNext());
+      Expect.equals(iterator.current, list[i]);
+    }
+  }
 }
 
-void expectAE(Function f) {
-  Expect.throws(f, (e) => e is ArgumentError);
+main() {
+  testGetRange([1, 2], 0, 1, true);
+  testGetRange([], 0, 0, true);
+  testGetRange([1, 2, 3], 0, 0, true);
+  testGetRange([1, 2, 3], 1, 3, true);
+  testGetRange(const [1, 2], 0, 1, false);
+  testGetRange(const [], 0, 0, false);
+  testGetRange(const [1, 2, 3], 0, 0, false);
+  testGetRange(const [1, 2, 3], 1, 3, false);
+  testGetRange("abcd".codeUnits, 0, 1, false);
+  testGetRange("abcd".codeUnits, 0, 0, false);
+  testGetRange("abcd".codeUnits, 1, 3, false);
+
+  expectRE(() => [1].getRange(-1, 1));
+  expectRE(() => [3].getRange(0, -1));
+  expectRE(() => [4].getRange(1, 0));
+
+  var list = [1, 2, 3, 4];
+  var iterable = list.getRange(1, 3);
+  Expect.equals(2, iterable.first);
+  Expect.equals(3, iterable.last);
+  list.length = 1;
+  Expect.isTrue(iterable.isEmpty);
+  list.add(99);
+  Expect.equals(99, iterable.single);
+  list.add(499);
+  Expect.equals(499, iterable.last);
+  Expect.equals(2, iterable.length);
 }
+
+void expectRE(Function f) {
+  Expect.throws(f, (e) => e is RangeError);
+}