Start on ArraySortedMap in C++ (#721)

* Implement ArraySortedMap.remove
* Implement ArraySortedMap.insert
* Ensure ArraySortedMap.insert avoids copying on duplicates
* Port more ArraySortedMapTests

2 files changed, 350 insertions, 0 deletions

diff --git a/Firestore/core/test/firebase/firestore/immutable/CMakeLists.txt b/Firestore/core/test/firebase/firestore/immutable/CMakeLists.txt
new file mode 100644
index 0000000..e7b0b6e
--- /dev/null
+++ b/Firestore/core/test/firebase/firestore/immutable/CMakeLists.txt
@@ -0,0 +1,22 @@
+# Copyright 2018 Google
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+cc_test(
+  firebase_firestore_immutable_test
+  SOURCES
+    array_sorted_map_test.cc
+  DEPENDS
+    firebase_firestore_immutable
+    firebase_firestore_util
+)
diff --git a/Firestore/core/test/firebase/firestore/immutable/array_sorted_map_test.cc b/Firestore/core/test/firebase/firestore/immutable/array_sorted_map_test.cc
new file mode 100644
index 0000000..4dc6a4b
--- /dev/null
+++ b/Firestore/core/test/firebase/firestore/immutable/array_sorted_map_test.cc
@@ -0,0 +1,328 @@
+/*
+ * Copyright 2018 Google
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "Firestore/core/src/firebase/firestore/immutable/array_sorted_map.h"
+
+#include <numeric>
+#include <random>
+
+#include "Firestore/core/src/firebase/firestore/util/secure_random.h"
+#include "gtest/gtest.h"
+
+namespace firebase {
+namespace firestore {
+namespace immutable {
+
+typedef ArraySortedMap<int, int> IntMap;
+constexpr IntMap::size_type kFixedSize = IntMap::kFixedSize;
+
+template <typename K, typename V>
+testing::AssertionResult NotFound(const ArraySortedMap<K, V>& set,
+                                  const K& key) {
+  auto found = set.find(key);
+  if (found == set.end()) {
+    return testing::AssertionSuccess();
+  } else {
+    return testing::AssertionFailure()
+           << "Should not have found (" << found->first << ", " << found->second
+           << ") @ " << found;
+  }
+}
+
+template <typename K, typename V>
+testing::AssertionResult Found(const ArraySortedMap<K, V>& map,
+                               const K& key,
+                               const V& expected) {
+  auto found = map.find(key);
+  if (found == map.end()) {
+    return testing::AssertionFailure() << "Did not find key " << key;
+  }
+  if (found->second == expected) {
+    return testing::AssertionSuccess();
+  } else {
+    return testing::AssertionFailure() << "Found entry was (" << found->first
+                                       << ", " << found->second << ")";
+  }
+}
+
+/**
+ * Creates a vector containing a sequence of integers from the given starting
+ * element up to, but not including, the given end element, with values
+ * incremented by the given step.
+ *
+ * If step is negative the sequence is in descending order (but still starting
+ * at start and ending before end).
+ */
+std::vector<int> Sequence(int start, int end, int step = 1) {
+  std::vector<int> result;
+  if (step > 0) {
+    for (int i = start; i < end; i += step) {
+      result.push_back(i);
+    }
+  } else {
+    for (int i = start; i > end; i += step) {
+      result.push_back(i);
+    }
+  }
+  return result;
+}
+
+/**
+ * Creates a vector containing a sequence of integers with the given number of
+ * elements, from zero up to, but not including the given value.
+ */
+std::vector<int> Sequence(int num_elements) {
+  return Sequence(0, num_elements);
+}
+
+/**
+ * Creates a copy of the given vector with contents shuffled randomly.
+ */
+std::vector<int> Shuffled(const std::vector<int>& values) {
+  std::vector<int> result(values);
+  util::SecureRandom rng;
+  std::shuffle(result.begin(), result.end(), rng);
+  return result;
+}
+
+/**
+ * Creates a copy of the given vector with contents sorted.
+ */
+std::vector<int> Sorted(const std::vector<int>& values) {
+  std::vector<int> result(values);
+  std::sort(result.begin(), result.end());
+  return result;
+}
+
+/**
+ * Creates a vector of pairs where each pair has the same first and second
+ * corresponding to an element in the given vector.
+ */
+std::vector<std::pair<int, int>> Pairs(const std::vector<int>& values) {
+  std::vector<std::pair<int, int>> result;
+  for (auto&& value : values) {
+    result.emplace_back(value, value);
+  }
+  return result;
+}
+
+/**
+ * Creates an ArraySortedMap by inserting a pair for each value in the vector.
+ * Each pair will have the same key and value.
+ */
+IntMap ToMap(const std::vector<int>& values) {
+  IntMap result;
+  for (auto&& value : values) {
+    result = result.insert(value, value);
+  }
+  return result;
+}
+
+/**
+ * Appends the contents of the given container to a new vector.
+ */
+template <typename Container>
+std::vector<typename Container::value_type> Append(const Container& container) {
+  std::vector<typename Container::value_type> result;
+  result.insert(result.begin(), container.begin(), container.end());
+  return result;
+}
+
+// TODO(wilhuff): ReverseTraversal
+
+#define ASSERT_SEQ_EQ(x, y) ASSERT_EQ((x), Append(y));
+#define EXPECT_SEQ_EQ(x, y) EXPECT_EQ((x), Append(y));
+
+TEST(ArraySortedMap, SearchForSpecificKey) {
+  IntMap map{{1, 3}, {2, 4}};
+
+  ASSERT_TRUE(Found(map, 1, 3));
+  ASSERT_TRUE(Found(map, 2, 4));
+  ASSERT_TRUE(NotFound(map, 3));
+}
+
+TEST(ArraySortedMap, RemoveKeyValuePair) {
+  IntMap map{{1, 3}, {2, 4}};
+
+  IntMap new_map = map.erase(1);
+  ASSERT_TRUE(Found(new_map, 2, 4));
+  ASSERT_TRUE(NotFound(new_map, 1));
+
+  // Make sure the original one is not mutated
+  ASSERT_TRUE(Found(map, 1, 3));
+  ASSERT_TRUE(Found(map, 2, 4));
+}
+
+TEST(ArraySortedMap, MoreRemovals) {
+  IntMap map = IntMap()
+                   .insert(1, 1)
+                   .insert(50, 50)
+                   .insert(3, 3)
+                   .insert(4, 4)
+                   .insert(7, 7)
+                   .insert(9, 9)
+                   .insert(1, 20)
+                   .insert(18, 18)
+                   .insert(3, 2)
+                   .insert(4, 71)
+                   .insert(7, 42)
+                   .insert(9, 88);
+
+  ASSERT_TRUE(Found(map, 7, 42));
+  ASSERT_TRUE(Found(map, 3, 2));
+  ASSERT_TRUE(Found(map, 1, 20));
+
+  IntMap s1 = map.erase(7);
+  IntMap s2 = map.erase(3);
+  IntMap s3 = map.erase(1);
+
+  ASSERT_TRUE(NotFound(s1, 7));
+  ASSERT_TRUE(Found(s1, 3, 2));
+  ASSERT_TRUE(Found(s1, 1, 20));
+
+  ASSERT_TRUE(Found(s2, 7, 42));
+  ASSERT_TRUE(NotFound(s2, 3));
+  ASSERT_TRUE(Found(s2, 1, 20));
+
+  ASSERT_TRUE(Found(s3, 7, 42));
+  ASSERT_TRUE(Found(s3, 3, 2));
+  ASSERT_TRUE(NotFound(s3, 1));
+}
+
+TEST(ArraySortedMap, RemovesMiddle) {
+  IntMap map{{1, 1}, {2, 2}, {3, 3}};
+  ASSERT_TRUE(Found(map, 1, 1));
+  ASSERT_TRUE(Found(map, 2, 2));
+  ASSERT_TRUE(Found(map, 3, 3));
+
+  IntMap s1 = map.erase(2);
+  ASSERT_TRUE(Found(s1, 1, 1));
+  ASSERT_TRUE(NotFound(s1, 2));
+  ASSERT_TRUE(Found(s1, 3, 3));
+}
+
+TEST(ArraySortedMap, Increasing) {
+  auto total = static_cast<int>(kFixedSize);
+  IntMap map;
+
+  for (int i = 0; i < total; i++) {
+    map = map.insert(i, i);
+  }
+  ASSERT_EQ(kFixedSize, map.size());
+
+  for (int i = 0; i < total; i++) {
+    map = map.erase(i);
+  }
+  ASSERT_EQ(0u, map.size());
+}
+
+TEST(ArraySortedMap, Override) {
+  IntMap map = IntMap().insert(10, 10).insert(10, 8);
+
+  ASSERT_TRUE(Found(map, 10, 8));
+  ASSERT_FALSE(Found(map, 10, 10));
+}
+
+TEST(ArraySortedMap, ChecksSize) {
+  std::vector<int> to_insert = Sequence(kFixedSize);
+  IntMap map = ToMap(to_insert);
+
+  // Replacing an existing entry should not hit increase size
+  map = map.insert(5, 10);
+
+  int next = kFixedSize;
+  ASSERT_DEATH_IF_SUPPORTED(map.insert(next, next), "new_size <= fixed_size");
+}
+
+TEST(ArraySortedMap, Empty) {
+  IntMap map = IntMap().insert(10, 10).erase(10);
+  EXPECT_TRUE(map.empty());
+  EXPECT_EQ(0u, map.size());
+  EXPECT_TRUE(NotFound(map, 1));
+  EXPECT_TRUE(NotFound(map, 10));
+}
+
+TEST(ArraySortedMap, EmptyGet) {
+  IntMap map;
+  EXPECT_TRUE(NotFound(map, 10));
+}
+
+TEST(ArraySortedMap, EmptySize) {
+  IntMap map;
+  EXPECT_TRUE(map.empty());
+  EXPECT_EQ(0u, map.size());
+}
+
+TEST(ArraySortedMap, EmptyRemoval) {
+  IntMap map;
+  IntMap new_map = map.erase(1);
+  EXPECT_TRUE(new_map.empty());
+  EXPECT_EQ(0u, new_map.size());
+  EXPECT_TRUE(NotFound(new_map, 1));
+}
+
+TEST(ArraySortedMap, InsertionAndRemovalOfMaxItems) {
+  auto expected_size = kFixedSize;
+  int n = static_cast<int>(expected_size);
+  std::vector<int> to_insert = Shuffled(Sequence(n));
+  std::vector<int> to_remove = Shuffled(to_insert);
+
+  // Add them to the map
+  IntMap map = ToMap(to_insert);
+  ASSERT_EQ(expected_size, map.size())
+      << "Check if all N objects are in the map";
+
+  // check the order is correct
+  ASSERT_SEQ_EQ(Pairs(Sorted(to_insert)), map);
+
+  for (int i : to_remove) {
+    map = map.erase(i);
+  }
+  ASSERT_EQ(0u, map.size()) << "Check we removed all of the items";
+}
+
+TEST(ArraySortedMap, BalanceProblem) {
+  std::vector<int> to_insert{1, 7, 8, 5, 2, 6, 4, 0, 3};
+
+  IntMap map = ToMap(to_insert);
+  ASSERT_SEQ_EQ(Pairs(Sorted(to_insert)), map);
+}
+
+// TODO(wilhuff): PredecessorKey
+
+// TODO(wilhuff): Iterators
+
+// TODO(wilhuff): IndexOf
+
+TEST(ArraySortedMap, AvoidsCopying) {
+  IntMap map = IntMap().insert(10, 20);
+  auto found = map.find(10);
+  ASSERT_NE(found, map.end());
+  EXPECT_EQ(20, found->second);
+
+  // Verify that inserting something with equal keys and values just returns
+  // the same underlying array.
+  IntMap duped = map.insert(10, 20);
+  auto duped_found = duped.find(10);
+
+  // If everything worked correctly, the backing array should not have been
+  // copied and the pointer to the entry with 10 as key should be the same.
+  EXPECT_EQ(found, duped_found);
+}
+
+}  // namespace immutable
+}  // namespace firestore
+}  // namespace firebase