Clean up GeoPoint port to C++ (#3153)

... based on things learned porting Timestamps.

There's no good way to include conversions equivalent to toGeoPoint in
FIRTimestamp, so pull out separate conversion functions that match other
similar things.

Firestore/Source/API/FIRGeoPoint+Internal.h

@@ -18,21 +18,11 @@
 
 NS_ASSUME_NONNULL_BEGIN
 
-namespace firebase {
-namespace firestore {
-class GeoPoint;
-}  // namespace firestore
-}  // namespace firebase
-
-namespace firestore = firebase::firestore;
-
 /** Internal FIRGeoPoint API we don't want exposed in our public header files. */
 @interface FIRGeoPoint (Internal)
 
 - (NSComparisonResult)compare:(FIRGeoPoint *)other;
 
-- (firestore::GeoPoint)toGeoPoint;
-
 @end
 
 NS_ASSUME_NONNULL_END

Firestore/Source/API/FIRGeoPoint.mm

@@ -88,10 +88,6 @@ NS_ASSUME_NONNULL_BEGIN
   }
 }
 
-- (firestore::GeoPoint)toGeoPoint {
-  return firestore::GeoPoint(self.latitude, self.longitude);
-}
-
 @end
 
 NS_ASSUME_NONNULL_END

Firestore/Source/API/FSTUserDataConverter.mm

@@ -30,6 +30,7 @@
 #import "Firestore/Source/API/FIRFieldValue+Internal.h"
 #import "Firestore/Source/API/FIRFirestore+Internal.h"
 #import "Firestore/Source/API/FIRGeoPoint+Internal.h"
+#import "Firestore/Source/API/converters.h"
 #import "Firestore/Source/Model/FSTFieldValue.h"
 #import "Firestore/Source/Model/FSTMutation.h"
 
@@ -49,6 +50,7 @@
 #include "absl/strings/match.h"
 
 namespace util = firebase::firestore::util;
+using firebase::firestore::GeoPoint;
 using firebase::firestore::api::ThrowInvalidArgument;
 using firebase::firestore::core::ParsedSetData;
 using firebase::firestore::core::ParsedUpdateData;
@@ -455,8 +457,7 @@ NS_ASSUME_NONNULL_BEGIN
     return [FSTTimestampValue timestampValue:truncatedTimestamp];
 
   } else if ([input isKindOfClass:[FIRGeoPoint class]]) {
-    FIRGeoPoint *geoPoint = input;
-    return FieldValue::FromGeoPoint([geoPoint toGeoPoint]).Wrap();
+    return FieldValue::FromGeoPoint(api::MakeGeoPoint(input)).Wrap();
 
   } else if ([input isKindOfClass:[NSData class]]) {
     NSData *inputData = input;

Firestore/Source/API/converters.h

@@ -0,0 +1,49 @@
+/*
+ * Copyright 2019 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_SOURCE_API_CONVERTERS_H_
+#define FIRESTORE_SOURCE_API_CONVERTERS_H_
+
+#if !defined(__OBJC__)
+#error "This header only supports Objective-C++"
+#endif  // !defined(__OBJC__)
+
+#import <Foundation/Foundation.h>
+
+@class FIRGeoPoint;
+
+NS_ASSUME_NONNULL_BEGIN
+
+namespace firebase {
+namespace firestore {
+
+class GeoPoint;
+
+namespace api {
+
+/** Converts a user-supplied FIRGeoPoint to the equivalent C++ GeoPoint. */
+GeoPoint MakeGeoPoint(FIRGeoPoint* geo_point);
+
+/** Converts a C++ GeoPoint to the equivalent Objective-C FIRGeoPoint. */
+FIRGeoPoint* MakeFIRGeoPoint(const GeoPoint& geo_point);
+
+}  // namespace api
+}  // namespace firestore
+}  // namespace firebase
+
+NS_ASSUME_NONNULL_END
+
+#endif  // FIRESTORE_SOURCE_API_CONVERTERS_H_

Firestore/Source/API/converters.mm

@@ -0,0 +1,42 @@
+/*
+ * Copyright 2019 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/Source/API/converters.h"
+
+#import "FIRGeoPoint.h"
+
+#include "Firestore/core/include/firebase/firestore/geo_point.h"
+
+NS_ASSUME_NONNULL_BEGIN
+
+namespace firebase {
+namespace firestore {
+namespace api {
+
+GeoPoint MakeGeoPoint(FIRGeoPoint* geo_point) {
+  return GeoPoint(geo_point.latitude, geo_point.longitude);
+}
+
+FIRGeoPoint* MakeFIRGeoPoint(const GeoPoint& geo_point) {
+  return [[FIRGeoPoint alloc] initWithLatitude:geo_point.latitude()
+                                     longitude:geo_point.longitude()];
+}
+
+}  // namespace api
+}  // namespace firestore
+}  // namespace firebase
+
+NS_ASSUME_NONNULL_END

Firestore/Source/Model/FSTFieldValue.h

@@ -26,7 +26,6 @@
 #include "Firestore/core/src/firebase/firestore/model/field_value_options.h"
 
 @class FIRTimestamp;
-@class FIRGeoPoint;
 
 namespace model = firebase::firestore::model;
 

Firestore/Source/Model/FSTFieldValue.mm

@@ -23,6 +23,7 @@
 #import "FIRTimestamp.h"
 
 #import "Firestore/Source/API/FIRGeoPoint+Internal.h"
+#import "Firestore/Source/API/converters.h"
 #import "Firestore/Source/Model/FSTDocumentKey.h"
 #import "Firestore/Source/Util/FSTClasses.h"
 
@@ -35,7 +36,7 @@
 #include "Firestore/core/src/firebase/firestore/util/string_apple.h"
 
 namespace util = firebase::firestore::util;
-using firebase::firestore::GeoPoint;
+using firebase::firestore::api::MakeFIRGeoPoint;
 using firebase::firestore::model::DatabaseId;
 using firebase::firestore::model::FieldMask;
 using firebase::firestore::model::FieldPath;
@@ -685,10 +686,8 @@ static const NSComparator StringComparator = ^NSComparisonResult(NSString *left,
       return MakeNSData(self.internalValue.blob_value());
     case FieldValue::Type::Reference:
       HARD_FAIL("TODO(rsgowman): implement");
-    case FieldValue::Type::GeoPoint: {
-      GeoPoint value = self.internalValue.geo_point_value();
-      return [[FIRGeoPoint alloc] initWithLatitude:value.latitude() longitude:value.longitude()];
-    }
+    case FieldValue::Type::GeoPoint:
+      return MakeFIRGeoPoint(self.internalValue.geo_point_value());
     case FieldValue::Type::Array:
     case FieldValue::Type::Object:
       HARD_FAIL("TODO(rsgowman): implement");