Add key-only projections to immutable C++ maps (#1166)

* Add a simple range adapter.
* Add SortedMap::keys
* Add SortedMap::keys_from
* Add SortedMap::keys_in

1 files changed, 60 insertions, 0 deletions

diff --git a/Firestore/core/test/firebase/firestore/immutable/sorted_map_test.cc b/Firestore/core/test/firebase/firestore/immutable/sorted_map_test.cc
index 25332c2..bcacb50 100644
--- a/Firestore/core/test/firebase/firestore/immutable/sorted_map_test.cc
+++ b/Firestore/core/test/firebase/firestore/immutable/sorted_map_test.cc
@@ -403,6 +403,66 @@ TYPED_TEST(SortedMapTest, IteratorInvalidation) {
   ASSERT_EQ(size, result.size());
 }
 
+TYPED_TEST(SortedMapTest, KeyIterator) {
+  std::vector<int> all = Sequence(this->large_number());
+  TypeParam map = ToMap<TypeParam>(Shuffled(all));
+
+  auto begin = map.keys().begin();
+  ASSERT_EQ(0, *begin);
+
+  auto end = map.keys().end();
+  ASSERT_EQ(all.size(), static_cast<size_t>(std::distance(begin, end)));
+
+  ASSERT_SEQ_EQ(all, map.keys());
+}
+
+TYPED_TEST(SortedMapTest, KeysFrom) {
+  std::vector<int> all = Sequence(2, 42, 2);
+  TypeParam map = ToMap<TypeParam>(Shuffled(all));
+  ASSERT_EQ(20u, map.size());
+
+  // Test from before keys.
+  ASSERT_SEQ_EQ(all, map.keys_from(0));
+
+  // Test from after keys.
+  ASSERT_SEQ_EQ(Empty(), map.keys_from(100));
+
+  // Test from a key in the map: should start at that key.
+  ASSERT_SEQ_EQ(Sequence(10, 42, 2), map.keys_from(10));
+
+  // Test from in between keys: should start just after that key.
+  ASSERT_SEQ_EQ(Sequence(12, 42, 2), map.keys_from(11));
+}
+
+TYPED_TEST(SortedMapTest, KeysIn) {
+  std::vector<int> all = Sequence(2, 42, 2);
+  TypeParam map = ToMap<TypeParam>(Shuffled(all));
+  ASSERT_EQ(20u, map.size());
+
+  // Constructs a sequence from `start` up to but not including `end` by 2.
+  auto Seq = [](int start, int end) { return Sequence(start, end, 2); };
+
+  ASSERT_SEQ_EQ(Empty(), map.keys_in(0, 1));   // before to before
+  ASSERT_SEQ_EQ(all, map.keys_in(0, 100))      // before to after
+  ASSERT_SEQ_EQ(Seq(2, 6), map.keys_in(0, 6))  // before to in map
+  ASSERT_SEQ_EQ(Seq(2, 8), map.keys_in(0, 7))  // before to in between
+
+  ASSERT_SEQ_EQ(Empty(), map.keys_in(100, 0));    // after to before
+  ASSERT_SEQ_EQ(Empty(), map.keys_in(100, 110));  // after to after
+  ASSERT_SEQ_EQ(Empty(), map.keys_in(100, 6));    // after to in map
+  ASSERT_SEQ_EQ(Empty(), map.keys_in(100, 7));    // after to in between
+
+  ASSERT_SEQ_EQ(Empty(), map.keys_in(6, 0));       // in map to before
+  ASSERT_SEQ_EQ(Seq(6, 42), map.keys_in(6, 100));  // in map to after
+  ASSERT_SEQ_EQ(Seq(6, 10), map.keys_in(6, 10));   // in map to in map
+  ASSERT_SEQ_EQ(Seq(6, 12), map.keys_in(6, 11));   // in map to in between
+
+  ASSERT_SEQ_EQ(Empty(), map.keys_in(7, 0));       // in between to before
+  ASSERT_SEQ_EQ(Seq(8, 42), map.keys_in(7, 100));  // in between to after
+  ASSERT_SEQ_EQ(Seq(8, 10), map.keys_in(7, 10));   // in between to key in map
+  ASSERT_SEQ_EQ(Seq(8, 14), map.keys_in(7, 13));   // in between to in between
+}
+
 }  // namespace immutable
 }  // namespace firestore
 }  // namespace firebase