Add ResponseStream

Author: intitni

Tool/Sources/OpenAIService/APIs/ResponseStream.swift

@@ -0,0 +1,45 @@
+import Foundation
+
+struct ResponseStream<Chunk>: AsyncSequence {
+    func makeAsyncIterator() -> Stream.AsyncIterator {
+        stream.makeAsyncIterator()
+    }
+
+    typealias Stream = AsyncThrowingStream<Chunk, Error>
+    typealias AsyncIterator = Stream.AsyncIterator
+    typealias Element = Chunk
+    
+    struct LineContent {
+        let chunk: Chunk?
+        let done: Bool
+    }
+
+    let stream: Stream
+
+    init(result: URLSession.AsyncBytes, lineExtractor: @escaping (String) throws -> LineContent) {
+        stream = AsyncThrowingStream<Chunk, Error> { continuation in
+            let task = Task {
+                do {
+                    for try await line in result.lines {
+                        if Task.isCancelled { break }
+                        let content = try lineExtractor(line)
+                        if let chunk = content.chunk {
+                            continuation.yield(chunk)
+                        }
+                        
+                        if content.done { break }
+                    }
+                    continuation.finish()
+                } catch {
+                    continuation.finish(throwing: error)
+                    result.task.cancel()
+                }
+            }
+            continuation.onTermination = { _ in
+                task.cancel()
+                result.task.cancel()
+            }
+        }
+    }
+}
+