Port FSTDocumentKeySet to C++ DocumentKeySet (#1229)

* Define a Comparator for DocumentKey

* Automated migration from FSTDocumentKeySet to DocumentKeySet

* Manual fixups for DocumentKeySet

* Delete FSTDocumentKeySet

3 files changed, 40 insertions, 8 deletions

diff --git a/Firestore/core/src/firebase/firestore/immutable/sorted_set.h b/Firestore/core/src/firebase/firestore/immutable/sorted_set.h
index 6828106..d78fd61 100644
--- a/Firestore/core/src/firebase/firestore/immutable/sorted_set.h
+++ b/Firestore/core/src/firebase/firestore/immutable/sorted_set.h
@@ -61,6 +61,13 @@ class SortedSet {
   explicit SortedSet(M&& map) : map_{std::move(map)} {
   }
 
+  SortedSet(std::initializer_list<value_type> entries, const C& comparator = {})
+      : map_{comparator} {
+    for (auto&& value : entries) {
+      map_ = map_.insert(value, {});
+    }
+  }
+
   bool empty() const {
     return map_.empty();
   }
@@ -124,7 +131,14 @@ class SortedSet {
   }
 
   friend bool operator==(const SortedSet& lhs, const SortedSet& rhs) {
-    return std::equal(lhs.begin(), lhs.end(), rhs.begin(), rhs.end());
+    if (lhs.size() != rhs.size()) {
+      return false;
+    }
+    return std::equal(lhs.begin(), lhs.end(), rhs.begin());
+  }
+
+  friend bool operator!=(const SortedSet& lhs, const SortedSet& rhs) {
+    return !(lhs == rhs);
   }
 
  private:
diff --git a/Firestore/core/src/firebase/firestore/model/document_key.h b/Firestore/core/src/firebase/firestore/model/document_key.h
index 7f6478f..6532b2e 100644
--- a/Firestore/core/src/firebase/firestore/model/document_key.h
+++ b/Firestore/core/src/firebase/firestore/model/document_key.h
@@ -17,6 +17,7 @@
 #ifndef FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_MODEL_DOCUMENT_KEY_H_
 #define FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_MODEL_DOCUMENT_KEY_H_
 
+#include <functional>
 #include <initializer_list>
 #include <memory>
 #include <string>
@@ -26,6 +27,7 @@
 #endif  // defined(__OBJC__)
 
 #include "Firestore/core/src/firebase/firestore/model/resource_path.h"
+#include "Firestore/core/src/firebase/firestore/util/comparison.h"
 #include "Firestore/core/src/firebase/firestore/util/hashing.h"
 #include "absl/strings/string_view.h"
 
@@ -118,6 +120,13 @@ inline bool operator>=(const DocumentKey& lhs, const DocumentKey& rhs) {
 }
 
 }  // namespace model
+
+namespace util {
+
+template <>
+struct Comparator<model::DocumentKey> : public std::less<model::DocumentKey> {};
+
+}  // namespace util
 }  // namespace firestore
 }  // namespace firebase
 
diff --git a/Firestore/core/test/firebase/firestore/model/document_key_test.cc b/Firestore/core/test/firebase/firestore/model/document_key_test.cc
index 619ee7f..71b78d1 100644
--- a/Firestore/core/test/firebase/firestore/model/document_key_test.cc
+++ b/Firestore/core/test/firebase/firestore/model/document_key_test.cc
@@ -21,8 +21,11 @@
 
 #include "Firestore/core/src/firebase/firestore/model/document_key.h"
 #include "Firestore/core/src/firebase/firestore/model/resource_path.h"
+#include "Firestore/core/test/firebase/firestore/testutil/testutil.h"
 #include "gtest/gtest.h"
 
+using firebase::firestore::testutil::Key;
+
 namespace firebase {
 namespace firestore {
 namespace model {
@@ -112,16 +115,16 @@ TEST(DocumentKey, IsDocumentKey) {
 }
 
 TEST(DocumentKey, Comparison) {
-  const DocumentKey abcd({"a", "b", "c", "d"});
-  const DocumentKey abcd_too({"a", "b", "c", "d"});
-  const DocumentKey xyzw({"x", "y", "z", "w"});
+  DocumentKey abcd = Key("a/b/c/d");
+  DocumentKey abcd_too = Key("a/b/c/d");
+  DocumentKey xyzw = Key("x/y/z/w");
   EXPECT_EQ(abcd, abcd_too);
   EXPECT_NE(abcd, xyzw);
 
-  const DocumentKey empty;
-  const DocumentKey a({"a", "a"});
-  const DocumentKey b({"b", "b"});
-  const DocumentKey ab({"a", "a", "b", "b"});
+  DocumentKey empty;
+  DocumentKey a = Key("a/a");
+  DocumentKey b = Key("b/b");
+  DocumentKey ab = Key("a/a/b/b");
 
   EXPECT_FALSE(empty < empty);
   EXPECT_TRUE(empty <= empty);
@@ -148,6 +151,12 @@ TEST(DocumentKey, Comparison) {
   EXPECT_TRUE(ab >= a);
 }
 
+TEST(DocumentKey, Comparator) {
+  DocumentKey abcd = Key("a/b/c/d");
+  DocumentKey xyzw = Key("x/y/z/w");
+  EXPECT_TRUE(util::Comparator<DocumentKey>{}(abcd, xyzw));
+}
+
 }  // namespace model
 }  // namespace firestore
 }  // namespace firebase