Adopt new AsyncStreaming types (#37)

This PR updates the `HTTPRequestConcludingAsyncReader` and
`HTTPResponseConcludingAsyncWriter` to use the new AsyncStreaming
(reader and writer) APIs. These types are currently being developed in
https://github.com/apple/swift-http-api-proposal but until that
repository is public, we have to vendor in the code in this repo.

Author: gjcairo

Package.swift

@@ -5,6 +5,7 @@ import PackageDescription
 let extraSettings: [SwiftSetting] = [
     .enableExperimentalFeature("SuppressedAssociatedTypes"),
     .enableExperimentalFeature("LifetimeDependence"),
+    .enableExperimentalFeature("Lifetimes"),
     .enableUpcomingFeature("LifetimeDependence"),
     .enableUpcomingFeature("NonisolatedNonsendingByDefault"),
     .enableUpcomingFeature("InferIsolatedConformances"),
@@ -21,7 +22,10 @@ let package = Package(
             targets: ["HTTPServer"])
     ],
     dependencies: [
-        .package(url: "https://github.com/apple/swift-collections.git", from: "1.0.4"),
+        .package(
+            url: "https://github.com/FranzBusch/swift-collections.git",
+            branch: "fb-async"
+        ),
         .package(url: "https://github.com/apple/swift-http-types.git", from: "1.0.0"),
         .package(url: "https://github.com/apple/swift-distributed-tracing.git", from: "1.0.0"),
         .package(url: "https://github.com/apple/swift-certificates.git", from: "1.16.0"),
@@ -48,7 +52,9 @@ let package = Package(
         .target(
             name: "HTTPServer",
             dependencies: [
+                "AsyncStreaming",
                 .product(name: "DequeModule", package: "swift-collections"),
+                .product(name: "BasicContainers", package: "swift-collections"),
                 .product(name: "X509", package: "swift-certificates"),
                 .product(name: "HTTPTypes", package: "swift-http-types"),
                 .product(name: "NIOCore", package: "swift-nio"),
@@ -71,6 +77,13 @@ let package = Package(
             ],
             swiftSettings: extraSettings
         ),
+        .target(
+            name: "AsyncStreaming",
+            dependencies: [
+                .product(name: "BasicContainers", package: "swift-collections")
+            ],
+            swiftSettings: extraSettings
+        ),
         .testTarget(
             name: "HTTPServerTests",
             dependencies: [

Sources/AsyncStreaming/EitherError.swift

@@ -0,0 +1,56 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift HTTP API Proposal open source project
+//
+// Copyright (c) 2025 Apple Inc. and the Swift HTTP API Proposal project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of Swift HTTP API Proposal project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+/// An enumeration that represents one of two possible error types.
+///
+/// ``EitherError`` provides a type-safe way to represent errors that can be one of two distinct
+/// error types.
+public enum EitherError<First: Error, Second: Error>: Error {
+    /// An error of the first type.
+    ///
+    /// The associated value contains the specific error instance of type `First`.
+    case first(First)
+
+    /// An error of the second type.
+    ///
+    /// The associated value contains the specific error instance of type `Second`.
+    case second(Second)
+
+    /// Throws the underlying error by unwrapping this either error.
+    ///
+    /// This method extracts and throws the actual error contained within the either error,
+    /// whether it's the first or second type. This is useful when you need to propagate
+    /// the original error without the either error wrapper.
+    ///
+    /// - Throws: The underlying error, either of type `First` or `Second`.
+    ///
+    /// ## Example
+    ///
+    /// ```swift
+    /// do {
+    ///     // Some operation that returns EitherError
+    ///     let result = try await operation()
+    /// } catch let eitherError as EitherError<NetworkError, ParseError> {
+    ///     try eitherError.unwrap() // Throws the original error
+    /// }
+    /// ```
+    public func unwrap() throws {
+        switch self {
+        case .first(let first):
+            throw first
+        case .second(let second):
+            throw second
+        }
+    }
+}

Sources/AsyncStreaming/Internal/InlineArray+convenience.swift

@@ -0,0 +1,24 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift HTTP API Proposal open source project
+//
+// Copyright (c) 2025 Apple Inc. and the Swift HTTP API Proposal project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of Swift HTTP API Proposal project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+@available(macOS 26.0, iOS 26.0, watchOS 26.0, tvOS 26.0, visionOS 26.0, *)
+extension InlineArray where Element: ~Copyable {
+    package static func one(value: consuming Element) -> InlineArray<1, Element> {
+        return InlineArray<1, Element>(first: value) { _ in fatalError() }
+    }
+
+    package static func zero(of elementType: Element.Type = Element.self) -> InlineArray<0, Element> {
+        return InlineArray<0, Element> { _ in }
+    }
+}

Sources/AsyncStreaming/Internal/Optional+SendingTake.swift

@@ -0,0 +1,22 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift HTTP API Proposal open source project
+//
+// Copyright (c) 2025 Apple Inc. and the Swift HTTP API Proposal project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of Swift HTTP API Proposal project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+extension Optional where Wrapped: ~Copyable {
+    @inlinable
+    mutating func takeSending() -> sending Self {
+        let result = consume self
+        self = nil
+        return result
+    }
+}