ContainerRegistry: Move digest() to its own file

Author: euanh

Sources/ContainerRegistry/Blobs.swift

@@ -14,17 +14,6 @@
 
 import Foundation
 import HTTPTypes
-import struct Crypto.SHA256
-
-/// Calculates the digest of a blob of data.
-/// - Parameter data: Blob of data to digest.
-/// - Returns: The blob's digest, in the format expected by the distribution protocol.
-public func digest<D: DataProtocol>(of data: D) -> ImageReference.Digest {
-    // SHA256 is required; some registries might also support SHA512
-    let hash = SHA256.hash(data: data)
-    let digest = hash.compactMap { String(format: "%02x", $0) }.joined()
-    return try! ImageReference.Digest("sha256:" + digest)
-}
 
 extension RegistryClient {
     // Internal helper method to initiate a blob upload in 'two shot' mode
@@ -61,9 +50,6 @@ extension RegistryClient {
     }
 }
 
-// The spec says that Docker- prefix headers are no longer to be used, but also specifies that the registry digest is returned in this header.
-extension HTTPField.Name { static let dockerContentDigest = Self("Docker-Content-Digest")! }
-
 public extension RegistryClient {
     func blobExists(repository: ImageReference.Repository, digest: ImageReference.Digest) async throws -> Bool {
         do {

Sources/ContainerRegistry/RegistryClient+Digest.swift

@@ -0,0 +1,30 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the SwiftContainerPlugin open source project
+//
+// Copyright (c) 2025 Apple Inc. and the SwiftContainerPlugin project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of SwiftContainerPlugin project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+import Foundation
+import HTTPTypes
+import struct Crypto.SHA256
+
+// The spec says that Docker- prefix headers are no longer to be used, but also specifies that the registry digest is returned in this header.
+extension HTTPField.Name { static let dockerContentDigest = Self("Docker-Content-Digest")! }
+
+/// Calculates the digest of a blob of data.
+/// - Parameter data: Blob of data to digest.
+/// - Returns: The blob's digest, in the format expected by the distribution protocol.
+public func digest(of data: any DataProtocol) -> ImageReference.Digest {
+    // SHA256 is required; some registries might also support SHA512
+    let hash = SHA256.hash(data: data)
+    let digest = hash.compactMap { String(format: "%02x", $0) }.joined()
+    return try! ImageReference.Digest("sha256:" + digest)
+}