C++ migration: remove the dependency on Objective-C Protobuf library

FirebaseFirestore.podspec

@@ -73,7 +73,6 @@ Google Cloud Firestore is a NoSQL document database built for automatic scaling,
 
   s.dependency 'gRPC-C++', '0.0.9'
   s.dependency 'leveldb-library', '~> 1.22'
-  s.dependency 'Protobuf', '~> 3.9', '>= 3.9.2'
   s.dependency 'nanopb', '~> 0.3.901'
 
   s.ios.frameworks = 'MobileCoreServices', 'SystemConfiguration'
@@ -86,7 +85,6 @@ Google Cloud Firestore is a NoSQL document database built for automatic scaling,
     'GCC_C_LANGUAGE_STANDARD' => 'c99',
     'GCC_PREPROCESSOR_DEFINITIONS' =>
       "FIRFirestore_VERSION=#{s.version} " +
-      'GPB_USE_PROTOBUF_FRAMEWORK_IMPORTS=1 ' +
       # The nanopb pod sets these defs, so we must too. (We *do* require 16bit
       # (or larger) fields, so we'd have to set at least PB_FIELD_16BIT
       # anyways.)

Firestore/Example/FuzzTests/FuzzingResources/Serializer/Corpus/ConvertTextToBinary.sh

@@ -21,6 +21,12 @@
 # XCode build target Firestore_FuzzTests_iOS that executes this script. XCode
 # defines these environment variables and makes them available to the script.
 
+if ! [ -x "$(command -v protoc)" ]; then
+  echo "This scripts needs the protoc command to be on the PATH."
+  echo "Please install protobuf (e.g., \`brew install protobuf\` on Mac)."
+  exit 1
+fi
+
 # Directory that contains the text protos to convert to binary protos.
 text_protos_dir="${SCRIPT_INPUT_FILE_0}"
 
@@ -51,7 +57,7 @@ for text_proto_file in "${text_protos_dir}"/*; do
   # Run the conversion.
   echo "Converting file: ${file_name} (type: ${message_type})"
   echo "${file_content}" \
-    | "${SRCROOT}/Pods/!ProtoCompiler/protoc" \
+    | protoc \
     -I"${SRCROOT}/../../Firestore/Protos/protos" \
     --encode=google.firestore.v1."${message_type}" \
     google/firestore/v1/document.proto > "${binary_protos_dir}/${file_name}"

Firestore/Example/Podfile

@@ -158,7 +158,6 @@ if is_platform(:ios)
       platform :ios, '9.0'
 
       pod 'LibFuzzer', :podspec => 'LibFuzzer.podspec', :inhibit_warnings => true
-      pod '!ProtoCompiler'
     end
   end
 end

Firestore/Example/Tests/Local/FSTLevelDBMigrationsTests.mm

@@ -21,12 +21,11 @@
 #include <string>
 #include <vector>
 
-#import "Firestore/Protos/objc/firestore/local/Mutation.pbobjc.h"
-#import "Firestore/Protos/objc/firestore/local/Target.pbobjc.h"
-
+#include "Firestore/Protos/nanopb/firestore/local/mutation.nanopb.h"
 #include "Firestore/core/src/firebase/firestore/local/leveldb_key.h"
 #include "Firestore/core/src/firebase/firestore/local/leveldb_migrations.h"
 #include "Firestore/core/src/firebase/firestore/local/leveldb_query_cache.h"
+#include "Firestore/core/src/firebase/firestore/nanopb/message.h"
 #include "Firestore/core/src/firebase/firestore/util/ordered_code.h"
 #include "Firestore/core/src/firebase/firestore/util/path.h"
 #include "Firestore/core/test/firebase/firestore/local/persistence_testing.h"
@@ -37,7 +36,8 @@
 NS_ASSUME_NONNULL_BEGIN
 
 using firebase::firestore::Error;
-using firebase::firestore::firestore_client_TargetGlobal;
+using firebase::firestore::firestore_client_MutationQueue;
+using firebase::firestore::firestore_client_WriteBatch;
 using firebase::firestore::local::LevelDbCollectionParentKey;
 using firebase::firestore::local::LevelDbDir;
 using firebase::firestore::local::LevelDbDocumentMutationKey;
@@ -272,25 +272,25 @@ - (void)testRemovesMutationBatches {
   {
     LevelDbTransaction transaction(_db.get(), "Setup Foo");
     // User 'foo' has two acknowledged mutations and one that is pending.
-    FSTPBMutationQueue *fooQueue = [[FSTPBMutationQueue alloc] init];
-    fooQueue.lastAcknowledgedBatchId = 2;
+    Message<firestore_client_MutationQueue> fooQueue;
+    fooQueue->last_acknowledged_batch_id = 2;
     std::string fooKey = LevelDbMutationQueueKey::Key("foo");
     transaction.Put(fooKey, fooQueue);
 
-    FSTPBWriteBatch *fooBatch1 = [[FSTPBWriteBatch alloc] init];
-    fooBatch1.batchId = 1;
+    Message<firestore_client_WriteBatch> fooBatch1;
+    fooBatch1->batch_id = 1;
     std::string fooBatchKey1 = LevelDbMutationKey::Key("foo", 1);
     transaction.Put(fooBatchKey1, fooBatch1);
     transaction.Put(LevelDbDocumentMutationKey::Key("foo", testWriteFoo, 1), emptyBuffer);
 
-    FSTPBWriteBatch *fooBatch2 = [[FSTPBWriteBatch alloc] init];
-    fooBatch2.batchId = 2;
+    Message<firestore_client_WriteBatch> fooBatch2;
+    fooBatch2->batch_id = 2;
     std::string fooBatchKey2 = LevelDbMutationKey::Key("foo", 2);
     transaction.Put(fooBatchKey2, fooBatch2);
     transaction.Put(LevelDbDocumentMutationKey::Key("foo", testWriteFoo, 2), emptyBuffer);
 
-    FSTPBWriteBatch *fooBatch3 = [[FSTPBWriteBatch alloc] init];
-    fooBatch3.batchId = 5;
+    Message<firestore_client_WriteBatch> fooBatch3;
+    fooBatch3->batch_id = 5;
     std::string fooBatchKey3 = LevelDbMutationKey::Key("foo", 5);
     transaction.Put(fooBatchKey3, fooBatch3);
     transaction.Put(LevelDbDocumentMutationKey::Key("foo", testWritePending, 5), emptyBuffer);
@@ -301,20 +301,20 @@ - (void)testRemovesMutationBatches {
   {
     LevelDbTransaction transaction(_db.get(), "Setup Bar");
     // User 'bar' has one acknowledged mutation and one that is pending
-    FSTPBMutationQueue *barQueue = [[FSTPBMutationQueue alloc] init];
-    barQueue.lastAcknowledgedBatchId = 3;
+    Message<firestore_client_MutationQueue> barQueue;
+    barQueue->last_acknowledged_batch_id = 3;
     std::string barKey = LevelDbMutationQueueKey::Key("bar");
     transaction.Put(barKey, barQueue);
 
-    FSTPBWriteBatch *barBatch1 = [[FSTPBWriteBatch alloc] init];
-    barBatch1.batchId = 3;
+    Message<firestore_client_WriteBatch> barBatch1;
+    barBatch1->batch_id = 3;
     std::string barBatchKey1 = LevelDbMutationKey::Key("bar", 3);
     transaction.Put(barBatchKey1, barBatch1);
     transaction.Put(LevelDbDocumentMutationKey::Key("bar", testWriteBar, 3), emptyBuffer);
     transaction.Put(LevelDbDocumentMutationKey::Key("bar", testWriteBaz, 3), emptyBuffer);
 
-    FSTPBWriteBatch *barBatch2 = [[FSTPBWriteBatch alloc] init];
-    barBatch2.batchId = 4;
+    Message<firestore_client_WriteBatch> barBatch2;
+    barBatch2->batch_id = 4;
     std::string barBatchKey2 = LevelDbMutationKey::Key("bar", 4);
     transaction.Put(barBatchKey2, barBatch2);
     transaction.Put(LevelDbDocumentMutationKey::Key("bar", testWritePending, 4), emptyBuffer);
@@ -325,8 +325,8 @@ - (void)testRemovesMutationBatches {
   {
     LevelDbTransaction transaction(_db.get(), "Setup Empty");
     // User 'empty' has no mutations
-    FSTPBMutationQueue *emptyQueue = [[FSTPBMutationQueue alloc] init];
-    emptyQueue.lastAcknowledgedBatchId = -1;
+    Message<firestore_client_MutationQueue> emptyQueue;
+    emptyQueue->last_acknowledged_batch_id = -1;
     std::string emptyKey = LevelDbMutationQueueKey::Key("empty");
     transaction.Put(emptyKey, emptyQueue);
     transaction.Commit();

Firestore/Example/Tests/Local/FSTLevelDBTransactionTests.mm

@@ -24,20 +24,27 @@
 // TODO(wilhuff): move this to the top once the test filename matches
 #include "Firestore/core/src/firebase/firestore/local/leveldb_transaction.h"
 
-#import "Firestore/Protos/objc/firestore/local/Mutation.pbobjc.h"
-#import "Firestore/Protos/objc/firestore/local/Target.pbobjc.h"
-
+#include "Firestore/Protos/nanopb/firestore/local/mutation.nanopb.h"
+#include "Firestore/Protos/nanopb/firestore/local/target.nanopb.h"
 #include "Firestore/core/src/firebase/firestore/local/leveldb_key.h"
+#include "Firestore/core/src/firebase/firestore/nanopb/byte_string.h"
+#include "Firestore/core/src/firebase/firestore/nanopb/message.h"
+#include "Firestore/core/src/firebase/firestore/nanopb/reader.h"
 #include "Firestore/core/src/firebase/firestore/util/path.h"
 #include "Firestore/core/test/firebase/firestore/local/persistence_testing.h"
 #include "absl/strings/string_view.h"
 #include "leveldb/db.h"
 
 NS_ASSUME_NONNULL_BEGIN
 
+using firebase::firestore::firestore_client_Target;
+using firebase::firestore::firestore_client_WriteBatch;
 using firebase::firestore::local::LevelDbDir;
 using firebase::firestore::local::LevelDbMutationKey;
 using firebase::firestore::local::LevelDbTransaction;
+using firebase::firestore::nanopb::ByteString;
+using firebase::firestore::nanopb::Message;
+using firebase::firestore::nanopb::StringReader;
 using firebase::firestore::util::Path;
 using leveldb::DB;
 using leveldb::Options;
@@ -199,22 +206,22 @@ - (void)testMutateDeleted {
 - (void)testProtobufSupport {
   LevelDbTransaction transaction(_db.get(), "testProtobufSupport");
 
-  FSTPBTarget *target = [FSTPBTarget message];
-  target.targetId = 1;
-  target.lastListenSequenceNumber = 2;
+  Message<firestore_client_Target> target;
+  target->target_id = 1;
+  target->last_listen_sequence_number = 2;
 
   std::string key("theKey");
   transaction.Put(key, target);
 
   std::string value;
   Status status = transaction.Get("theKey", &value);
-  NSData *result = [[NSData alloc] initWithBytesNoCopy:(void *)value.data()
-                                                length:value.size()
-                                          freeWhenDone:NO];
-  NSError *error;
-  FSTPBTarget *parsed = [FSTPBTarget parseFromData:result error:&error];
-  XCTAssertNil(error);
-  XCTAssertTrue([target isEqual:parsed]);
+
+  ByteString bytes{value};
+  StringReader reader{bytes};
+  auto parsed = Message<firestore_client_Target>::TryParse(&reader);
+  XCTAssertTrue(reader.ok());
+  XCTAssertEqual(target->target_id, parsed->target_id);
+  XCTAssertEqual(target->last_listen_sequence_number, parsed->last_listen_sequence_number);
 }
 
 - (void)testCanIterateAndDelete {
@@ -286,8 +293,8 @@ - (void)testDeletingAheadOfAnIterator {
 
 - (void)testToString {
   std::string key = LevelDbMutationKey::Key("user1", 42);
-  FSTPBWriteBatch *message = [FSTPBWriteBatch message];
-  message.batchId = 42;
+  Message<firestore_client_WriteBatch> message;
+  message->batch_id = 42;
 
   LevelDbTransaction transaction(_db.get(), "testToString");
   std::string description = transaction.ToString();