replacing Auth by C++ auth implementation (#802)

* lazy replacing FST(Firebase)CredentialsProvider by (Firebase)CredentialsProvider

* lazy replacing FSTUser by User

* adding error-code parameter to TokenListener

* actually use const user& instead of pointer; also add an error util

* add HashUser and pass into the unordered_map

* use User in test

* use c++ CredentialsProvider and subclass in test

* fix unit test

* use explicit capture in lambda instead of capture all by reference

* cache currentUser explicitly when reset sync engineer test driver

* objc object should be captured by value in lambda

* replacing Auth/FSTUser by C++ auth implementation

* address changes

* replacing FSTGetTokenResult by C++ Token implementation

* address changes

* fix unintentional change in merging

* patch the change in objc Auth up-stream

* somehow, the lambda-version of set-user-change-listener does not work... fallback to block

* address changes

* fix another const& v.s. dispatch bug

* fix more const& v.s. dispatch bug  zxu123 committed

* fix a bad sync line

* address changes

* address change

* address change

* fix upstream change from merge

* fix upstream changes

* Suggested fixes for cpp/port_auth (#846)

* Get rid of MockDatastore factory

This avoids the need to statically allocate (and leak) a credentials
provider

* Use absl::make_unique

std::make_unique technically does not exist until C++14.

* #include <utility> for std::move

* Use std::future for the initial user

* fix style

1 files changed, 115 insertions, 0 deletions

diff --git a/Firestore/core/include/firebase/firestore/firestore_errors.h b/Firestore/core/include/firebase/firestore/firestore_errors.h
new file mode 100644
index 0000000..7a0ff7c
--- /dev/null
+++ b/Firestore/core/include/firebase/firestore/firestore_errors.h
@@ -0,0 +1,115 @@
+/*
+ * 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_INCLUDE_FIREBASE_FIRESTORE_FIRESTORE_ERRORS_H_
+#define FIRESTORE_CORE_INCLUDE_FIREBASE_FIRESTORE_FIRESTORE_ERRORS_H_
+
+namespace firebase {
+namespace firestore {
+
+/**
+ * Error codes used by Cloud Firestore.
+ *
+ * The codes are in sync with the Firestore iOS client SDK header file
+ * FIRFirestoreErrors.h.
+ */
+enum FirestoreErrorCode {
+  /**
+   * The operation completed successfully. NSError objects will never have a
+   * code with this value.
+   */
+  Ok = 0,
+
+  /** The operation was cancelled (typically by the caller). */
+  Cancelled = 1,
+
+  /** Unknown error or an error from a different error domain. */
+  Unknown = 2,
+
+  /**
+   * Client specified an invalid argument. Note that this differs from
+   * FailedPrecondition. InvalidArgument indicates arguments that are
+   * problematic regardless of the state of the system (e.g., an invalid field
+   * name).
+   */
+  InvalidArgument = 3,
+
+  /**
+   * Deadline expired before operation could complete. For operations that
+   * change the state of the system, this error may be returned even if the
+   * operation has completed successfully. For example, a successful response
+   * from a server could have been delayed long enough for the deadline to
+   * expire.
+   */
+  DeadlineExceeded = 4,
+
+  /** Some requested document was not found. */
+  NotFound = 5,
+
+  /** Some document that we attempted to create already exists. */
+  AlreadyExists = 6,
+
+  /** The caller does not have permission to execute the specified operation. */
+  PermissionDenied = 7,
+
+  /**
+   * Some resource has been exhausted, perhaps a per-user quota, or perhaps the
+   * entire file system is out of space.
+   */
+  ResourceExhausted = 8,
+
+  /**
+   * Operation was rejected because the system is not in a state required for
+   * the operation's execution.
+   */
+  FailedPrecondition = 9,
+
+  /**
+   * The operation was aborted, typically due to a concurrency issue like
+   * transaction aborts, etc.
+   */
+  Aborted = 10,
+
+  /** Operation was attempted past the valid range. */
+  OutOfRange = 11,
+
+  /** Operation is not implemented or not supported/enabled. */
+  Unimplemented = 12,
+
+  /**
+   * Internal errors. Means some invariants expected by underlying system has
+   * been broken. If you see one of these errors, something is very broken.
+   */
+  Internal = 13,
+
+  /**
+   * The service is currently unavailable. This is a most likely a transient
+   * condition and may be corrected by retrying with a backoff.
+   */
+  Unavailable = 14,
+
+  /** Unrecoverable data loss or corruption. */
+  DataLoss = 15,
+
+  /** The request does not have valid authentication credentials for the
+     operation. */
+  Unauthenticated = 16
+};
+
+}  // namespace firestore
+}  // namespace firebase
+
+#endif  // FIRESTORE_CORE_INCLUDE_FIREBASE_FIRESTORE_FIRESTORE_ERRORS_H_