Firestore Swift Cpp Experiment

FirebaseCombineSwift.podspec

@@ -59,6 +59,7 @@ for internal testing only. It should not be published.
 
   s.pod_target_xcconfig = {
     'HEADER_SEARCH_PATHS' => '"${PODS_TARGET_SRCROOT}"',
+    'SWIFT_OBJC_INTEROP_MODE' => 'objcxx',
   }
 
   s.test_spec 'unit' do |unit_tests|
@@ -81,7 +82,8 @@ for internal testing only. It should not be published.
     unit_tests.exclude_files = 'FirebaseCombineSwift/Tests/Unit/**/*Template.swift'
     unit_tests.requires_app_host = true
     unit_tests.pod_target_xcconfig = {
-      'SWIFT_OBJC_BRIDGING_HEADER' => '$(PODS_TARGET_SRCROOT)/FirebaseCombineSwift/Tests/Unit/FirebaseCombine-unit-Bridging-Header.h'
+      'SWIFT_OBJC_BRIDGING_HEADER' => '$(PODS_TARGET_SRCROOT)/FirebaseCombineSwift/Tests/Unit/FirebaseCombine-unit-Bridging-Header.h',
+      'SWIFT_OBJC_INTEROP_MODE' => 'objcxx',
     }
     unit_tests.dependency 'OCMock'
     unit_tests.dependency 'FirebaseAuthTestingSupport'

FirebaseCore/Sources/Public/FirebaseCore/FIRVersion.h

@@ -19,7 +19,16 @@
 NS_ASSUME_NONNULL_BEGIN
 
 /** Returns the current version of Firebase. */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 NS_SWIFT_NAME(FirebaseVersion())
 NSString* FIRFirebaseVersion(void);
 
+#ifdef __cplusplus
+}
+#endif
+
 NS_ASSUME_NONNULL_END

FirebaseFirestore.podspec

@@ -31,6 +31,12 @@ Google Cloud Firestore is a NoSQL document database built for automatic scaling,
     'FirebaseFirestoreInternal/**/*.[mh]',
     'Firestore/Swift/Source/**/*.swift',
   ]
+
+  s.pod_target_xcconfig = {
+    # Enables C++ <-> Swift interop (by default it's only C)
+    "SWIFT_OBJC_INTEROP_MODE" => "objcxx",
+  }
+
   s.resource_bundles = {
     "#{s.module_name}_Privacy" => 'Firestore/Swift/Source/Resources/PrivacyInfo.xcprivacy'
   }

FirebaseFirestoreInternal.podspec

@@ -28,7 +28,10 @@ Google Cloud Firestore is a NoSQL document database built for automatic scaling,
   # Header files that constitute the interface to this module. Only Objective-C
   # headers belong here, since FirebaseFirestore is primarily an Objective-C
   # framework.
-  s.public_header_files = 'Firestore/Source/Public/FirebaseFirestore/*.h'
+  s.public_header_files = [
+    'Firestore/Source/Public/FirebaseFirestore/*.h',
+    'Firestore/core/swift/include/*.h'
+  ]
 
   # source_files contains most of the header and source files for the project.
   # This includes files named in `public_header_files`.
@@ -52,6 +55,7 @@ Google Cloud Firestore is a NoSQL document database built for automatic scaling,
     'Firestore/core/include/**/*.{cc,mm}',
     'Firestore/core/src/**/*.{cc,mm}',
     'FirebaseAuth/Interop/**/*.h',
+    'Firestore/core/swift/**/*.{cc,h}',
   ]
 
   # Internal headers that aren't necessarily globally unique. Most C++ internal

Firestore/Source/API/FIRInterface.mm

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2024 Google LLC
+ *
+ * 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.
+ */
+
+#import <Foundation/Foundation.h>
+
+#import "Firestore/Source/Public/FirebaseFirestore/FIRInterface.h"
+
+#import "Firestore/core/src/api/used_by_objective_c.h"
+#include "Firestore/core/src/util/string_apple.h"
+
+using firebase::firestore::util::MakeString;
+
+NS_ASSUME_NONNULL_BEGIN
+
+@implementation FIRInterface
+
++ (void)print:(NSString *)content {
+  CppInterfaceCalledByObjectiveC::print(MakeString(content));
+}
+
+@end
+
+NS_ASSUME_NONNULL_END

Firestore/Source/Public/FirebaseFirestore/FIRInterface.h

@@ -0,0 +1,29 @@
+/*
+ * Copyright 2024 Google LLC
+ *
+ * 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.
+ */
+
+#import <Foundation/Foundation.h>
+
+NS_ASSUME_NONNULL_BEGIN
+
+@interface FIRInterface : NSObject
+
+#pragma mark - Create Filter
+
++ (void)print:(NSString *)content;
+
+@end
+
+NS_ASSUME_NONNULL_END

Firestore/Swift/Source/SwiftAPI/SwiftCppAPI.swift

@@ -0,0 +1,25 @@
+/*
+ * Copyright 2024 Google LLC
+ *
+ * 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.
+ */
+
+#if SWIFT_PACKAGE
+  @_exported import FirebaseFirestoreCpp
+#endif // SWIFT_PACKAGE
+
+public class SwiftCallingCpp {
+  public init(_ value: String) {
+    CppInterfaceCalledBySwift.print(std.string(value))
+  }
+}

Firestore/core/CMakeLists.txt

@@ -218,6 +218,8 @@ firebase_ios_glob(
   src/objc/*.h
   src/remote/*.cc
   src/remote/*.h
+  swift/include/*.h
+  swift/src/*.cc
   EXCLUDE ${nanopb_sources}
 )
 

Firestore/core/src/api/used_by_objective_c.cc

@@ -0,0 +1,22 @@
+/*
+ * Copyright 2024 Google LLC
+ *
+ * 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 "used_by_objective_c.h"
+#include <iostream>
+
+void CppInterfaceCalledByObjectiveC::print(std::string content) {
+  std::cout << "C++ function runs with value: " << content << std::endl;
+}

Firestore/core/src/api/used_by_objective_c.h

@@ -0,0 +1,27 @@
+/*
+ * Copyright 2024 Google LLC
+ *
+ * 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 FIREBASE_USED_BY_SWIFT_H
+#define FIREBASE_USED_BY_SWIFT_H
+
+#include <string>
+
+class CppInterfaceCalledByObjectiveC {
+ public:
+  static void print(std::string content);
+};
+
+#endif  // FIREBASE_USED_BY_SWIFT_H

Firestore/core/swift/include/FirebaseFirestoreCpp.h

@@ -0,0 +1,22 @@
+/*
+ * Copyright 2024 Google LLC
+ *
+ * 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 FIREBASE_FIREBASEFIRESTORECPP_H
+#define FIREBASE_FIREBASEFIRESTORECPP_H
+
+#import "used_by_swift.h"
+
+#endif  // FIREBASE_FIREBASEFIRESTORECPP_H

Firestore/core/swift/include/used_by_swift.h

@@ -0,0 +1,27 @@
+/*
+ * Copyright 2024 Google LLC
+ *
+ * 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 FIREBASE_USED_BY_SWIFT_H
+#define FIREBASE_USED_BY_SWIFT_H
+
+#include <string>
+
+class CppInterfaceCalledBySwift {
+ public:
+  static void print(std::string content);
+};
+
+#endif  // FIREBASE_USED_BY_SWIFT_H

Firestore/core/swift/src/used_by_swift.cc

@@ -0,0 +1,22 @@
+/*
+ * Copyright 2024 Google LLC
+ *
+ * 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 "../include/used_by_swift.h"
+#include <iostream>
+
+void CppInterfaceCalledBySwift::print(std::string content) {
+  std::cout << "C++ function runs with value: " << content << std::endl;
+}

Package.swift

@@ -476,7 +476,10 @@ let package = Package(
       dependencies: [
         "FirebaseFirestoreTarget",
       ],
-      path: "FirebaseCombineSwift/Sources/Firestore"
+      path: "FirebaseCombineSwift/Sources/Firestore",
+      swiftSettings: [
+        .interoperabilityMode(.Cxx), // C++ interoperability setting
+      ]
     ),
     .target(
       name: "FirebaseStorageCombineSwift",
@@ -1171,7 +1174,10 @@ let package = Package(
         "FirebaseStorage",
         .product(name: "nanopb", package: "nanopb"),
       ],
-      path: "SwiftPMTests/swift-test"
+      path: "SwiftPMTests/swift-test",
+      swiftSettings: [
+        .interoperabilityMode(.Cxx), // C++ interoperability setting
+      ]
     ),
     .testTarget(
       name: "analytics-import-test",
@@ -1399,6 +1405,17 @@ func firestoreWrapperTarget() -> Target {
   )
 }
 
+func firebaseFirestoreCppTarget() -> Target {
+  return .target(
+    name: "FirebaseFirestoreCpp",
+    path: "Firestore/core/swift",
+    publicHeadersPath: "include", // Path to the public headers
+    cxxSettings: [
+      .headerSearchPath("include"), // Ensure the header search path is correct
+    ]
+  )
+}
+
 func firestoreTargets() -> [Target] {
   if ProcessInfo.processInfo.environment["FIREBASE_SOURCE_FIRESTORE"] != nil {
     return [
@@ -1469,13 +1486,15 @@ func firestoreTargets() -> [Target] {
           .linkedLibrary("c++"),
         ]
       ),
+      firebaseFirestoreCppTarget(),
       .target(
         name: "FirebaseFirestore",
         dependencies: [
           "FirebaseCore",
           "FirebaseCoreExtension",
           "FirebaseFirestoreInternalWrapper",
           "FirebaseSharedSwift",
+          "FirebaseFirestoreCpp",
         ],
         path: "Firestore",
         exclude: [
@@ -1496,7 +1515,10 @@ func firestoreTargets() -> [Target] {
         sources: [
           "Swift/Source/",
         ],
-        resources: [.process("Source/Resources/PrivacyInfo.xcprivacy")]
+        resources: [.process("Source/Resources/PrivacyInfo.xcprivacy")],
+        swiftSettings: [
+          .interoperabilityMode(.Cxx), // C++ interoperability setting
+        ]
       ),
     ]
   }
@@ -1542,9 +1564,13 @@ func firestoreTargets() -> [Target] {
         "FirebaseCoreExtension",
         "leveldb",
         "FirebaseSharedSwift",
+        "FirebaseFirestoreCpp",
       ],
       path: "Firestore/Swift/Source",
       resources: [.process("Resources/PrivacyInfo.xcprivacy")],
+      swiftSettings: [
+        .interoperabilityMode(.Cxx), // C++ interoperability setting
+      ],
       linkerSettings: [
         .linkedFramework("SystemConfiguration", .when(platforms: [.iOS, .macOS, .tvOS])),
         .linkedFramework("UIKit", .when(platforms: [.iOS, .tvOS])),
@@ -1561,5 +1587,6 @@ func firestoreTargets() -> [Target] {
       publicHeadersPath: "."
     ),
     firestoreInternalTarget,
+    firebaseFirestoreCppTarget(),
   ]
 }