replacing FSTGetTokenResult by C++ Token implementation (#805)

* replacing Auth/FSTUser by C++ auth implementation

* address changes

* replacing FSTGetTokenResult by C++ Token implementation

* address changes

* address changes

* fix another const& v.s. dispatch bug

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

* fix

* passing by value in callback

8 files changed, 54 insertions, 14 deletions

diff --git a/Firestore/core/src/firebase/firestore/auth/credentials_provider.h b/Firestore/core/src/firebase/firestore/auth/credentials_provider.h
index 2a52c99..917f8e1 100644
--- a/Firestore/core/src/firebase/firestore/auth/credentials_provider.h
+++ b/Firestore/core/src/firebase/firestore/auth/credentials_provider.h
@@ -31,11 +31,11 @@ namespace auth {
 // `TokenErrorListener` is a listener that gets a token or an error.
 // token: An auth token as a string, or nullptr if error occurred.
 // error: The error if one occurred, or else nullptr.
-typedef std::function<void(const Token& token, const absl::string_view error)>
+typedef std::function<void(Token token, const absl::string_view error)>
     TokenListener;
 
 // Listener notified with a User change.
-typedef std::function<void(const User& user)> UserChangeListener;
+typedef std::function<void(User user)> UserChangeListener;
 
 /**
  * Provides methods for getting the uid and token for the current user and
diff --git a/Firestore/core/src/firebase/firestore/auth/token.cc b/Firestore/core/src/firebase/firestore/auth/token.cc
index 0618ddb..4ee1b69 100644
--- a/Firestore/core/src/firebase/firestore/auth/token.cc
+++ b/Firestore/core/src/firebase/firestore/auth/token.cc
@@ -21,7 +21,15 @@ namespace firestore {
 namespace auth {
 
 Token::Token(const absl::string_view token, const User& user)
-    : token_(token), user_(user) {
+    : token_(token), user_(user), is_valid_(true) {
+}
+
+Token::Token() : token_(), user_(User::Unauthenticated()), is_valid_(false) {
+}
+
+const Token& Token::Invalid() {
+  static const Token kInvalidToken;
+  return kInvalidToken;
 }
 
 }  // namespace auth
diff --git a/Firestore/core/src/firebase/firestore/auth/token.h b/Firestore/core/src/firebase/firestore/auth/token.h
index f3b7363..ff8d2f0 100644
--- a/Firestore/core/src/firebase/firestore/auth/token.h
+++ b/Firestore/core/src/firebase/firestore/auth/token.h
@@ -20,6 +20,7 @@
 #include <string>
 
 #include "Firestore/core/src/firebase/firestore/auth/user.h"
+#include "Firestore/core/src/firebase/firestore/util/firebase_assert.h"
 #include "absl/strings/string_view.h"
 
 namespace firebase {
@@ -45,6 +46,7 @@ class Token {
 
   /** The actual raw token. */
   const std::string& token() const {
+    FIREBASE_ASSERT(is_valid_);
     return token_;
   }
 
@@ -56,9 +58,26 @@ class Token {
     return user_;
   }
 
+  /**
+   * Whether the token is a valid one.
+   *
+   * ## Portability notes: Invalid token is the equivalent of nil in the iOS
+   * token implementation. We use value instead of pointer for Token instance in
+   * the C++ migration.
+   */
+  bool is_valid() const {
+    return is_valid_;
+  }
+
+  /** Returns an invalid token. */
+  static const Token& Invalid();
+
  private:
+  Token();
+
   const std::string token_;
   const User user_;
+  const bool is_valid_;
 };
 
 }  // namespace auth
diff --git a/Firestore/core/src/firebase/firestore/util/string_apple.h b/Firestore/core/src/firebase/firestore/util/string_apple.h
index fe2a487..3f6b814 100644
--- a/Firestore/core/src/firebase/firestore/util/string_apple.h
+++ b/Firestore/core/src/firebase/firestore/util/string_apple.h
@@ -42,7 +42,16 @@ inline NSString* WrapNSStringNoCopy(const absl::string_view str) {
   return WrapNSStringNoCopy(str.data());
 }
 
-// Creates an absl::string_view wrapper for the contents of the given NSString.
+// Translates a string_view string to the equivalent NSString by making a copy.
+inline NSString* WrapNSString(const absl::string_view str) {
+  return [[NSString alloc]
+      initWithBytes:const_cast<void*>(static_cast<const void*>(str.data()))
+             length:str.length()
+           encoding:NSUTF8StringEncoding];
+}
+
+// Creates an absl::string_view wrapper for the contents of the given
+// NSString.
 inline absl::string_view MakeStringView(NSString* str) {
   return absl::string_view(
       [str UTF8String], [str lengthOfBytesUsingEncoding:NSUTF8StringEncoding]);
diff --git a/Firestore/core/test/firebase/firestore/auth/credentials_provider_test.cc b/Firestore/core/test/firebase/firestore/auth/credentials_provider_test.cc
index 1748422..9ae71ba 100644
--- a/Firestore/core/test/firebase/firestore/auth/credentials_provider_test.cc
+++ b/Firestore/core/test/firebase/firestore/auth/credentials_provider_test.cc
@@ -25,7 +25,7 @@ namespace auth {
 #define UNUSED(x) (void)(x)
 
 TEST(CredentialsProvider, Typedef) {
-  TokenListener token_listener = [](const Token& token,
+  TokenListener token_listener = [](Token token,
                                     const absl::string_view error) {
     UNUSED(token);
     UNUSED(error);
@@ -37,9 +37,7 @@ TEST(CredentialsProvider, Typedef) {
   EXPECT_EQ(nullptr, token_listener);
   EXPECT_FALSE(token_listener);
 
-  UserChangeListener user_change_listener = [](const User& user) {
-    UNUSED(user);
-  };
+  UserChangeListener user_change_listener = [](User user) { UNUSED(user); };
   EXPECT_NE(nullptr, user_change_listener);
   EXPECT_TRUE(user_change_listener);
 
diff --git a/Firestore/core/test/firebase/firestore/auth/empty_credentials_provider_test.cc b/Firestore/core/test/firebase/firestore/auth/empty_credentials_provider_test.cc
index 123f952..39012f0 100644
--- a/Firestore/core/test/firebase/firestore/auth/empty_credentials_provider_test.cc
+++ b/Firestore/core/test/firebase/firestore/auth/empty_credentials_provider_test.cc
@@ -25,8 +25,7 @@ namespace auth {
 TEST(EmptyCredentialsProvider, GetToken) {
   EmptyCredentialsProvider credentials_provider;
   credentials_provider.GetToken(
-      /*force_refresh=*/true,
-      [](const Token& token, const absl::string_view error) {
+      /*force_refresh=*/true, [](Token token, const absl::string_view error) {
         EXPECT_EQ("", token.token());
         const User& user = token.user();
         EXPECT_EQ("", user.uid());
@@ -37,7 +36,7 @@ TEST(EmptyCredentialsProvider, GetToken) {
 
 TEST(EmptyCredentialsProvider, SetListener) {
   EmptyCredentialsProvider credentials_provider;
-  credentials_provider.SetUserChangeListener([](const User& user) {
+  credentials_provider.SetUserChangeListener([](User user) {
     EXPECT_EQ("", user.uid());
     EXPECT_FALSE(user.is_authenticated());
   });
diff --git a/Firestore/core/test/firebase/firestore/auth/firebase_credentials_provider_test.mm b/Firestore/core/test/firebase/firestore/auth/firebase_credentials_provider_test.mm
index 8d2b361..e98d3d8 100644
--- a/Firestore/core/test/firebase/firestore/auth/firebase_credentials_provider_test.mm
+++ b/Firestore/core/test/firebase/firestore/auth/firebase_credentials_provider_test.mm
@@ -65,8 +65,7 @@ TEST_F(FirebaseCredentialsProviderTest, GetToken) {
 
   FirebaseCredentialsProvider credentials_provider([FIRApp defaultApp]);
   credentials_provider.GetToken(
-      /*force_refresh=*/true,
-      [](const Token& token, const absl::string_view error) {
+      /*force_refresh=*/true, [](Token token, const absl::string_view error) {
         EXPECT_EQ("", token.token());
         const User& user = token.user();
         EXPECT_EQ("I'm a fake uid.", user.uid());
@@ -82,7 +81,7 @@ TEST_F(FirebaseCredentialsProviderTest, SetListener) {
   }
 
   FirebaseCredentialsProvider credentials_provider([FIRApp defaultApp]);
-  credentials_provider.SetUserChangeListener([](const User& user) {
+  credentials_provider.SetUserChangeListener([](User user) {
     EXPECT_EQ("I'm a fake uid.", user.uid());
     EXPECT_TRUE(user.is_authenticated());
   });
diff --git a/Firestore/core/test/firebase/firestore/auth/token_test.cc b/Firestore/core/test/firebase/firestore/auth/token_test.cc
index a0f2c48..8f784d6 100644
--- a/Firestore/core/test/firebase/firestore/auth/token_test.cc
+++ b/Firestore/core/test/firebase/firestore/auth/token_test.cc
@@ -26,6 +26,14 @@ TEST(Token, Getter) {
   Token token("token", User("abc"));
   EXPECT_EQ("token", token.token());
   EXPECT_EQ(User("abc"), token.user());
+  EXPECT_TRUE(token.is_valid());
+}
+
+TEST(Token, InvalidToken) {
+  const Token& token = Token::Invalid();
+  EXPECT_ANY_THROW(token.token());
+  EXPECT_EQ(User::Unauthenticated(), token.user());
+  EXPECT_FALSE(token.is_valid());
 }
 
 }  // namespace auth