port FieldMask to C++ (#998)

* port FieldMask to C++

* address changes

* address changes

* fix test

* address change

* fix lint

* address changes

* Revert "address changes"

This reverts commit c75bb42851b785ab0838bb23679f87dfad9df4bb.

2 files changed, 98 insertions, 0 deletions

diff --git a/Firestore/core/src/firebase/firestore/model/CMakeLists.txt b/Firestore/core/src/firebase/firestore/model/CMakeLists.txt
index 78f5cd6..f6c5efe 100644
--- a/Firestore/core/src/firebase/firestore/model/CMakeLists.txt
+++ b/Firestore/core/src/firebase/firestore/model/CMakeLists.txt
@@ -22,6 +22,7 @@ cc_library(
     document.h
     document_key.cc
     document_key.h
+    field_mask.h
     field_path.cc
     field_path.h
     field_value.cc
diff --git a/Firestore/core/src/firebase/firestore/model/field_mask.h b/Firestore/core/src/firebase/firestore/model/field_mask.h
new file mode 100644
index 0000000..a9f509a
--- /dev/null
+++ b/Firestore/core/src/firebase/firestore/model/field_mask.h
@@ -0,0 +1,97 @@
+/*
+ * 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.
+ */
+
+#ifndef FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_MODEL_FIELD_MASK_H_
+#define FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_MODEL_FIELD_MASK_H_
+
+#include <initializer_list>
+#include <string>
+#include <utility>
+#include <vector>
+
+#include "Firestore/core/src/firebase/firestore/model/field_path.h"
+
+namespace firebase {
+namespace firestore {
+namespace model {
+
+/**
+ * Provides a set of fields that can be used to partially patch a document.
+ * FieldMask is used in conjunction with FieldValue of Object type.
+ *
+ * Examples:
+ *   foo - Overwrites foo entirely with the provided value. If foo is not
+ *       present in the companion FieldValue, the field is deleted.
+ *   foo.bar - Overwrites only the field bar of the object foo. If foo is not an
+ *       object, foo is replaced with an object containing bar.
+ */
+class FieldMask {
+ public:
+  using const_iterator = std::vector<FieldPath>::const_iterator;
+
+  FieldMask(std::initializer_list<FieldPath> list) : fields_{list} {
+  }
+  explicit FieldMask(const std::vector<FieldPath>& fields) : fields_{fields} {
+  }
+  explicit FieldMask(std::vector<FieldPath>&& fields)
+      : fields_{std::move(fields)} {
+  }
+
+  const_iterator begin() const {
+    return fields_.begin();
+  }
+  const_iterator end() const {
+    return fields_.end();
+  }
+
+  std::string ToString() const {
+    // Ideally, one should use a string builder. Since this is only non-critical
+    // code for logging and debugging, the logic is kept simple here.
+    std::string result("{ ");
+    for (const FieldPath& field : fields_) {
+      result += field.CanonicalString() + " ";
+    }
+    return result + "}";
+  }
+
+#if defined(__OBJC__)
+  FieldMask() {
+  }
+
+  NSUInteger Hash() const {
+    NSUInteger hashResult = 0;
+    for (const FieldPath& field : fields_) {
+      hashResult = hashResult * 31u + field.Hash();
+    }
+    return hashResult;
+  }
+#endif
+
+  friend bool operator==(const FieldMask& lhs, const FieldMask& rhs);
+
+ private:
+  std::vector<FieldPath> fields_;
+};
+
+inline bool operator==(const FieldMask& lhs, const FieldMask& rhs) {
+  return lhs.fields_ == rhs.fields_;
+}
+
+}  // namespace model
+}  // namespace firestore
+}  // namespace firebase
+
+#endif  // FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_MODEL_FIELD_MASK_H_