Implement Query (part 1) and add improved support for Futures

Examples/FireBaseUI/FireBaseUIViewController.swift

@@ -246,7 +246,7 @@ internal final class FireBaseUIViewController: ViewController {
         let document = firestore
             .collection("users")
             .document(user.uid)
-        let snapshot = try await document.get()
+        let snapshot = try await document.getDocument()
         await MainActor.run { [weak self] in
           guard let self else { return }
           userDetailsLabel.text = snapshot.debugDescription

Examples/FireBaseUI/FirestoreTestingViewController.swift

@@ -67,8 +67,8 @@ internal final class FirestoreTestingViewController: ViewController {
       await buttonsEnabled(false)
       let document = Firestore.firestore().document(path)
       do {
-        let snapshot = try await document.get()
-        await displayData(data: snapshot?.debugDescription ?? "No snapshot")
+        let snapshot = try await document.getDocument()
+        await displayData(data: snapshot.debugDescription)
       } catch {
         await displayError(error: error)
       }

Sources/FirebaseAuth/FirebaseAuth+Swift.swift

@@ -2,7 +2,7 @@
 
 @_exported
 import firebase
-@_spi(Error)
+@_spi(Internal)
 import FirebaseCore
 
 import CxxShim

Sources/FirebaseAuth/FirebaseUser+Swift.swift

@@ -5,7 +5,7 @@ import Foundation
 
 @_exported
 import firebase
-@_spi(Error)
+@_spi(Internal)
 import FirebaseCore
 
 public typealias User = firebase.auth.User

Sources/FirebaseCore/FirebaseError.swift

@@ -4,7 +4,7 @@ public struct FirebaseError: Error {
   public let code: CInt
   public let message: String
 
-  @_spi(Error)
+  @_spi(Internal)
   public init(code: CInt, message: String) {
     self.code = code
     self.message = message

Sources/FirebaseCore/FutureProtocol.swift

@@ -0,0 +1,58 @@
+// SPDX-License-Identifier: BSD-3-Clause
+
+@_exported
+import firebase
+
+import Foundation
+
+@_spi(Internal)
+public typealias FutureCompletionType = swift_firebase.swift_cxx_shims.firebase.FutureCompletionType
+
+// This protocol enables extracting common code for Future handling. Because
+// C++ interop is limited for templated class types, we need to invent a
+// protocol to reflect the features of a Future<R> that should be generically
+// available. This works by having a C++ annotation (see ConformingFuture<R>)
+// that specifies this protocol conformance.
+@_spi(Internal)
+public protocol FutureProtocol {
+  associatedtype ResultType
+  func error() -> Int32
+  func __error_messageUnsafe() -> UnsafePointer<CChar>?
+  func __resultUnsafe() -> UnsafePointer<ResultType>?
+  func CallOnCompletion(_ completion: FutureCompletionType, _ user_data: UnsafeMutableRawPointer?)
+}
+
+// A home for various helper functions that make it easier to work with
+// Firebase Future objects from Swift.
+@_spi(Internal)
+public extension FutureProtocol {
+  // Callsites retain their own reference to the Future<R>, but they still need
+  // a way to know when the Future completes. This provides that mechanism.
+  // While the underlying Firebase `OnCompletion` method can provide a reference
+  // back to the Future, we don't need to expose that here.
+  func setCompletion(_ completion: @escaping () -> Void) {
+    CallOnCompletion({ ptr in
+      Unmanaged<CompletionWrapper>.fromOpaque(ptr!).takeRetainedValue().completion()
+    }, Unmanaged.passRetained(CompletionWrapper(completion)).toOpaque())
+  }
+
+  // A convenient way to access the result or error of a Future. Handles the
+  // messy details.
+  var resultAndError: (ResultType?, Error?) {
+    let error = error()
+    guard error == 0 else {
+      let message = String(cString: __error_messageUnsafe()!)
+      return (nil, FirebaseError(code: error, message: message))
+    }
+    return (__resultUnsafe().pointee, nil)
+  }
+}
+
+// The Unmanaged type only works with classes, so we need a wrapper for the
+// completion callback.
+private class CompletionWrapper {
+  let completion: () -> Void
+  init(_ completion: @escaping () -> Void) {
+    self.completion = completion
+  }
+}

Sources/FirebaseFirestore/DocumentChange+Swift.swift

@@ -9,19 +9,19 @@ public typealias DocumentChange = firebase.firestore.DocumentChange
 public typealias DocumentChangeType = firebase.firestore.DocumentChange.`Type`
 
 extension DocumentChange {
-    public var type: DocumentChangeType {
-        swift_firebase.swift_cxx_shims.firebase.firestore.document_change_type(self)
-    }
+  public var type: DocumentChangeType {
+    swift_firebase.swift_cxx_shims.firebase.firestore.document_change_type(self)
+  }
 
-    public var document: DocumentSnapshot {
-        swift_firebase.swift_cxx_shims.firebase.firestore.document_change_document(self)
-    }
+  public var document: DocumentSnapshot {
+    swift_firebase.swift_cxx_shims.firebase.firestore.document_change_document(self)
+  }
 
-    public var oldIndex: UInt {
-        UInt(swift_firebase.swift_cxx_shims.firebase.firestore.document_change_old_index(self))
-    }
+  public var oldIndex: UInt {
+    UInt(swift_firebase.swift_cxx_shims.firebase.firestore.document_change_old_index(self))
+  }
 
-    public var newIndex: UInt {
-        UInt(swift_firebase.swift_cxx_shims.firebase.firestore.document_change_new_index(self))
-    }
+  public var newIndex: UInt {
+    UInt(swift_firebase.swift_cxx_shims.firebase.firestore.document_change_new_index(self))
+  }
 }

Sources/FirebaseFirestore/DocumentReference+Swift.swift

@@ -2,7 +2,7 @@
 
 @_exported
 import firebase
-@_spi(Error)
+@_spi(Internal)
 import FirebaseCore
 
 import CxxShim
@@ -33,27 +33,24 @@ extension DocumentReference {
     String(swift_firebase.swift_cxx_shims.firebase.firestore.document_path(self))
   }
 
-  public func get() async throws -> DocumentSnapshot? {
-    typealias Promise = CheckedContinuation<UnsafeMutablePointer<firebase.firestore.DocumentSnapshot>, any Error>
-    let snapshot = try await withCheckedThrowingContinuation { (continuation: Promise) in
-      let future = swift_firebase.swift_cxx_shims.firebase.firestore.document_get(self, .default)
-      withUnsafePointer(to: continuation) { continuation in
-        future.OnCompletion_SwiftWorkaround({ future, pvContinuation in
-          let pContinuation = pvContinuation?.assumingMemoryBound(to: Promise.self)
-          if future.pointee.error() == 0 {
-            pContinuation.pointee.resume(returning: .init(mutating: future.pointee.__resultUnsafe()))
-          } else {
-            let code = future.pointee.error()
-            let message = String(cString: future.pointee.__error_messageUnsafe()!)
-            pContinuation.pointee.resume(throwing: FirebaseError(code: code, message: message))
-          }
-        }, UnsafeMutableRawPointer(mutating: continuation))
-      }
-      future.Wait(firebase.FutureBase.kWaitTimeoutInfinite)
-    }
+  public func getDocument(completion: @escaping (DocumentSnapshot?, Error?) -> Void) {
+    let future = swift_firebase.swift_cxx_shims.firebase.firestore.document_get(self, .default)
+    future.setCompletion({
+      let (snapshot, error) = future.resultAndError
+      completion(snapshot, error)
+    })
+  }
 
-    guard snapshot.pointee.exists else { return nil }
-    return snapshot.pointee.is_valid() ? snapshot.pointee : nil
+  public func getDocument() async throws -> DocumentSnapshot {
+    try await withCheckedThrowingContinuation { continuation in
+      getDocument(completion: { snapshot, error in
+        if let error {
+          continuation.resume(throwing: error)
+        } else {
+          continuation.resume(returning: snapshot ?? .init())
+        }
+      })
+    }
   }
 
   public func addSnapshotListener(_ listener: @escaping SnapshotListenerCallback) -> ListenerRegistration {

Sources/FirebaseFirestore/DocumentSnapshot+Swift.swift

@@ -2,7 +2,7 @@
 
 @_exported
 import firebase
-@_spi(Error)
+@_spi(Internal)
 import FirebaseCore
 
 import CxxShim

Sources/FirebaseFirestore/Firestore+Swift.swift

@@ -2,7 +2,7 @@
 
 @_exported
 import firebase
-@_spi(Error)
+@_spi(Internal)
 import FirebaseCore
 
 import CxxShim

Sources/FirebaseFirestore/ListenerRegistration.swift

@@ -2,7 +2,7 @@
 
 @_exported
 import firebase
-@_spi(Error)
+@_spi(Internal)
 import FirebaseCore
 
 import CxxShim

Sources/FirebaseFirestore/Query+Swift.swift

@@ -0,0 +1,36 @@
+// SPDX-License-Identifier: BSD-3-Clause
+
+@_exported
+import firebase
+@_spi(Internal)
+import FirebaseCore
+
+import CxxShim
+
+public typealias Query = firebase.firestore.Query
+
+extension Query {
+  var firestore: Firestore {
+    swift_firebase.swift_cxx_shims.firebase.firestore.query_firestore(self)
+  }
+
+  func getDocuments(completion: @escaping (QuerySnapshot?, Error?) -> Void) {
+    let future = swift_firebase.swift_cxx_shims.firebase.firestore.query_get(self, .default)
+    future.setCompletion({
+      let (snapshot, error) = future.resultAndError
+      completion(snapshot, error)
+    })
+  }
+
+  func getDocuments() async throws -> QuerySnapshot {
+    try await withCheckedThrowingContinuation { continuation in
+      getDocuments() { snapshot, error in
+        if let error {
+          continuation.resume(throwing: error)
+        } else {
+          continuation.resume(returning: snapshot ?? .init())
+        }
+      }
+    }
+  }
+}

Sources/FirebaseFirestore/QuerySnapshot+Swift.swift

@@ -0,0 +1,8 @@
+// SPDX-License-Identifier: BSD-3-Clause
+
+@_exported
+import firebase
+
+import CxxShim
+
+public typealias QuerySnapshot = firebase.firestore.QuerySnapshot

Sources/FirebaseFirestore/Settings+Swift.swift

@@ -2,7 +2,7 @@
 
 @_exported
 import firebase
-@_spi(Error)
+@_spi(Internal)
 import FirebaseCore
 
 import CxxShim

Sources/firebase/include/FirebaseCore.hh

@@ -1,7 +1,34 @@
-
 #ifndef firebase_include_FirebaseCore_hh
 #define firebase_include_FirebaseCore_hh
 
 #include <firebase/util.h>
 
+#include <stdio.h>
+
+namespace swift_firebase::swift_cxx_shims::firebase {
+
+typedef void (*FutureCompletionType)(void*);
+
+// This class exists to provide protocol conformance to FutureProtocol.  It
+// also provides a method to invoke `OnCompletion` in a way that works from
+// Swift. We can ignore the `FutureBase` param as the Swift caller can just
+// retain the Future as part of its closure.
+template <class R> class ConformingFuture: public ::firebase::Future<R> {
+ public:
+  typedef R ResultType;
+  typedef ::firebase::Future<R> FutureType;
+
+  ConformingFuture(const FutureType& rhs) : FutureType(rhs) {}
+
+  void CallOnCompletion(
+      _Nonnull FutureCompletionType completion,
+      _Nullable void* user_data) const {
+    OnCompletion([completion, user_data](const FutureBase&) {
+      completion(user_data);
+    });
+  }
+} __attribute__((swift_attr("conforms_to:FirebaseCore.FutureProtocol")));
+
+} // namespace swift_firebase::swift_cxx_shims::firebase
+
 #endif

Sources/firebase/include/FirebaseFirestore.hh

@@ -5,6 +5,8 @@
 
 #include <firebase/firestore.h>
 
+#include "FirebaseCore.hh"
+
 // Functions defined in this namespace are used to get around the lack of
 // virtual function support currently in Swift. As that support changes
 // these functions will go away whenever possible.
@@ -43,14 +45,15 @@ document_path(const ::firebase::firestore::DocumentReference document) {
   return document.path();
 }
 
-inline ::firebase::Future<::firebase::firestore::DocumentSnapshot>
+inline ::swift_firebase::swift_cxx_shims::firebase::ConformingFuture<
+    ::firebase::firestore::DocumentSnapshot>
 document_get(const ::firebase::firestore::DocumentReference document,
              ::firebase::firestore::Source source =
                  ::firebase::firestore::Source::kDefault) {
   return document.Get(source);
 }
 
-inline ::firebase::Future<void>
+inline ::swift_firebase::swift_cxx_shims::firebase::ConformingFuture<void>
 document_set_data(::firebase::firestore::DocumentReference document,
                   const ::firebase::firestore::MapFieldValue data,
                   const ::firebase::firestore::SetOptions options) {
@@ -166,6 +169,21 @@ document_change_new_index(const ::firebase::firestore::DocumentChange change) {
   return change.new_index();
 }
 
+// MARK: Query
+
+inline ::firebase::firestore::Firestore *
+query_firestore(::firebase::firestore::Query query) {
+  return query.firestore();
+}
+
+inline ::swift_firebase::swift_cxx_shims::firebase::ConformingFuture<
+    ::firebase::firestore::QuerySnapshot>
+query_get(const ::firebase::firestore::Query query,
+             ::firebase::firestore::Source source =
+                 ::firebase::firestore::Source::kDefault) {
+  return query.Get(source);
+}
+
 } // namespace swift_firebase::swift_cxx_shims::firebase::firestore
 
 #endif