Reapply "New implementation of {,Linked}Hash{Set,Map}."

tests/corelib/hash_map2_test.dart

+// Copyright (c) 2013, 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.
+
+// Tests of hash map behavior, with focus in iteration and concurrent
+// modification errors.
+
+library hash_map2_test;
+import 'dart:collection';
+
+testMap(Map newMap(), Map newMapFrom(Map map)) {
+  Map gen(int from, int to) {
+    Map map = new LinkedHashMap();
+    for (int i = from; i < to; i++) map[i] = i;
+    return map;
+  }
+
+  bool odd(int n) => (n & 1) == 1;
+  bool even(int n) => (n & 1) == 0;
+  void addAll(Map toMap, Map fromMap) {
+    fromMap.forEach((k, v) { toMap[k] = v; });
+  }
+
+  {  // Test growing to largish capacity.
+    Map map = newMap();
+
+    for (int i = 0; i < 256; i++) {
+      map[i] = i;
+    }
+    addAll(map, gen(256, 512));
+    addAll(map, newMapFrom(gen(512, 1000)));
+    Expect.equals(1000, map.length);
+
+    // Remove half.
+    for (int i = 0; i < 1000; i += 2) map.remove(i);
+    Expect.equals(500, map.length);
+    Expect.isFalse(map.keys.any(even));
+    Expect.isTrue(map.keys.every(odd));
+
+    // Re-add all.
+    addAll(map, gen(0, 1000));
+    Expect.equals(1000, map.length);
+  }
+
+  {  // Test having many deleted elements.
+    Map map = newMap();
+    map[0] = 0;
+    for (int i = 0; i < 1000; i++) {
+      map[i + 1] = i + 1;
+      map.remove(i);
+      Expect.equals(1, map.length);
+    }
+  }
+
+  {  // Test having many elements with same hashCode
+    Map map = newMap();
+    for (int i = 0; i < 1000; i++) {
+      map[new BadHashCode()] = 0;
+    }
+    Expect.equals(1000, map.length);
+  }
+
+  {  // Check concurrent modification
+    Map map = newMap()..[0] = 0..[1] = 1;
+
+    {  // Test adding before a moveNext.
+      Iterator iter = map.keys.iterator;
+      iter.moveNext();
+      map[1] = 9;  // Updating existing key isn't a modification.
+      iter.moveNext();
+      map[2] = 2;
+      Expect.throws(iter.moveNext, (e) => e is Error);
+    }
+
+    {  // Test adding after last element.
+      Iterator iter = map.keys.iterator;
+      Expect.equals(3, map.length);
+      iter.moveNext();
+      iter.moveNext();
+      iter.moveNext();
+      map[3] = 3;
+      Expect.throws(iter.moveNext, (e) => e is Error);
+    }
+
+    {  // Test removing during iteration.
+      Iterator iter = map.keys.iterator;
+      iter.moveNext();
+      map.remove(1000);  // Not a modification if it's not there.
+      iter.moveNext();
+      int n = iter.current;
+      map.remove(n);
+      // Removing doesn't change current.
+      Expect.equals(n, iter.current);
+      Expect.throws(iter.moveNext, (e) => e is Error);
+    }
+
+    {  // Test removing after last element.
+      Iterator iter = map.keys.iterator;
+      Expect.equals(3, map.length);
+      iter.moveNext();
+      iter.moveNext();
+      iter.moveNext();
+      int n = iter.current;
+      map.remove(n);
+      // Removing doesn't change current.
+      Expect.equals(n, iter.current);
+      Expect.throws(iter.moveNext, (e) => e is Error);
+    }
+
+    {  // Test that updating value of existing key doesn't cause concurrent
+       // modification error.
+      Iterator iter = map.keys.iterator;
+      Expect.equals(2, map.length);
+      iter.moveNext();
+      int n = iter.current;
+      map[n] = n * 2;
+      iter.moveNext();
+      Expect.equals(map[iter.current], iter.current);
+    }
+
+    {  // Test that modification during putIfAbsent is not an error.
+      map.putIfAbsent(4, () {
+        map[5] = 5;
+        map[4] = -1;
+        return 4;
+      });
+      Expect.equals(4, map[4]);
+      Expect.equals(5, map[5]);
+    }
+
+    {  // Check adding many existing keys isn't considered modification.
+      Map map2 = newMap();
+      for (var key in map.keys) {
+        map2[key] = map[key] + 1;
+      }
+      Iterator iter = map.keys.iterator;
+      addAll(map, map2);
+      // Shouldn't throw.
+      iter.moveNext();
+    }
+  }
+
+  {  // Regression test for bug in putIfAbsent where adding an element
+     // that make the table grow, can be lost.
+    Map map = newMap();
+    map.putIfAbsent("S", () => 0);
+    map.putIfAbsent("T", () => 0);
+    map.putIfAbsent("U", () => 0);
+    map.putIfAbsent("C", () => 0);
+    map.putIfAbsent("a", () => 0);
+    map.putIfAbsent("b", () => 0);
+    map.putIfAbsent("n", () => 0);
+    Expect.isTrue(map.containsKey("n"));
+  }
+
+  {  // Check that putIfAbsent works just as well as put.
+    Map map = newMap();
+    for (int i = 0; i < 128; i++) {
+      map.putIfAbsent(i, () => i);
+      Expect.isTrue(map.containsKey(i));
+      map.putIfAbsent(i >> 1, () => -1);  // Never triggers.
+    }
+    for (int i = 0; i < 128; i++) {
+      Expect.equals(i, map[i]);
+    }
+  }
+
+  {  // Check that updating existing elements is not a modification.
+     // This must be the case even if the underlying data structure is
+     // nearly full.
+     for (int i = 1; i < 128; i++) {
+        // Create maps of different sizes, some of which should be
+        // at a limit of the underlying data structure.
+        Map map = newMapFrom(gen(0, i));
+
+        // ForEach-iteration.
+        map.forEach((key, v) {
+          Expect.equals(key, map[key]);
+          map[key] = key + 1;
+          map.remove(1000);  // Removing something not there.
+          map.putIfAbsent(key, () => Expect.fail("SHOULD NOT BE ABSENT"));
+          // Doesn't cause ConcurrentModificationError.
+        });
+
+        // for-in iteration.
+        for (int key in map.keys) {
+          Expect.equals(key + 1, map[key]);
+          map[key] = map[key] + 1;
+          map.remove(1000);  // Removing something not there.
+          map.putIfAbsent(key, () => Expect.fail("SHOULD NOT BE ABSENT"));
+          // Doesn't cause ConcurrentModificationError.
+        }
+
+        // Raw iterator.
+        Iterator iter = map.keys.iterator;
+        for (int key = 0; key < i; key++) {
+          Expect.equals(key + 2, map[key]);
+          map[key] = key + 3;
+          map.remove(1000);  // Removing something not there.
+          map.putIfAbsent(key, () => Expect.fail("SHOULD NOT BE ABSENT"));
+          // Doesn't cause ConcurrentModificationError on the moveNext.
+        }
+        iter.moveNext();  // Should not throw.
+
+        // Remove a lot of elements, which can cause a re-tabulation.
+        for (int key = 1; key < i; key++) {
+          Expect.equals(key + 3, map[key]);
+          map.remove(key);
+        }
+        iter = map.keys.iterator;
+        map[0] = 2;
+        iter.moveNext();  // Should not throw.
+     }
+  }
+
+
+  {  // Check that null can be in the map.
+    Map map = newMap();
+    map[null] = 0;
+    Expect.equals(1, map.length);
+    Expect.isTrue(map.containsKey(null));
+    Expect.isNull(map.keys.first);
+    Expect.isNull(map.keys.last);
+    map[null] = 1;
+    Expect.equals(1, map.length);
+    Expect.isTrue(map.containsKey(null));
+    map.remove(null);
+    Expect.isTrue(map.isEmpty);
+    Expect.isFalse(map.containsKey(null));
+
+    // Created using map.from.
+    map = newMapFrom(new Map()..[null] = 0);
+    Expect.equals(1, map.length);
+    Expect.isTrue(map.containsKey(null));
+    Expect.isNull(map.keys.first);
+    Expect.isNull(map.keys.last);
+    map[null] = 1;
+    Expect.equals(1, map.length);
+    Expect.isTrue(map.containsKey(null));
+    map.remove(null);
+    Expect.isTrue(map.isEmpty);
+    Expect.isFalse(map.containsKey(null));
+
+    Map fromMap = new Map();
+    fromMap[1] = 0;
+    fromMap[2] = 0;
+    fromMap[3] = 0;
+    fromMap[null] = 0;
+    fromMap[4] = 0;
+    fromMap[5] = 0;
+    fromMap[6] = 0;
+    Expect.equals(7, fromMap.length);
+
+    // map that grows with null in it.
+    map = newMapFrom(fromMap);
+    Expect.equals(7, map.length);
+    for (int i = 7; i < 128; i++) {
+      map[i] = 0;
+    }
+    Expect.equals(128, map.length);
+    Expect.isTrue(map.containsKey(null));
+    map[null] = 1;
+    Expect.equals(128, map.length);
+    Expect.isTrue(map.containsKey(null));
+    map.remove(null);
+    Expect.equals(127, map.length);
+    Expect.isFalse(map.containsKey(null));
+  }
+}
+
+void main() {
+  Expect.isTrue(new HashMap<int, String>() is Map<int, String>);
+  Expect.isTrue(new LinkedHashMap<int, String>() is Map<int, String>);
+  Expect.isTrue(new HashMap<String, int>.from({}) is Map<String, int>);
+  Expect.isTrue(new LinkedHashMap<String, int>.from({}) is Map<String, int>);
+  Expect.isTrue(<String, int>{} is Map<String, int>);
+  Expect.isTrue(const <String, int>{} is Map<String, int>);
+
+  testMap(() => new HashMap(), (m) => new HashMap.from(m));
+  testMap(() => new LinkedHashMap(), (m) => new LinkedHashMap.from(m));
+}
+
+
+class BadHashCode {
+  static int idCounter = 0;
+  final int id;
+  BadHashCode() : id = idCounter++;
+  int get hashCode => 42;
+}