Use Apple's Unified Logging framework on macOS 10.12

The old way of writing the buffers to a file was not a scaling solution
and it was prone to breaking. This also is not a scalable solution
(i.e., does not work on Linux) but it is at least stable.

Author: RLovelett

Sources/JSONRPC/Types/Request.swift

@@ -10,6 +10,10 @@ import Argo
 import Curry
 import Foundation
 import Runes
+import os.log
+
+@available(macOS 10.12, *)
+private let log = OSLog(subsystem: "me.lovelett.langserver-swift", category: "Request")
 
 /// A JSON-RPC
 public enum Request {
@@ -78,6 +82,10 @@ public enum Request {
             throw PredefinedError.parse
         }
 
+        if #available(macOS 10.12, *) {
+            os_log("%{public}@", log: log, type: .default, String(bytes: data, encoding: .utf8)!)
+        }
+
         let json = JSON(serialized)
 
         let dMethod: Decoded<String> = (json <| "method")

Sources/JSONRPC/Types/Response.swift

@@ -9,10 +9,13 @@
 import Argo
 import Foundation
 import Ogra
+import os.log
 
 fileprivate let headerSeparator = "\r\n"
 fileprivate let headerTerminator = "\r\n\r\n"
 fileprivate let pattern = headerTerminator.data(using: .utf8)!
+@available(macOS 10.12, *)
+private let log = OSLog(subsystem: "me.lovelett.langserver-swift", category: "Response")
 
 public struct Response {
 
@@ -86,7 +89,11 @@ public struct Response {
 
         headerData?.append(jsonData)
 
-        return headerData ?? pattern
+        let response = headerData ?? pattern
+        if #available(macOS 10.12, *), let msg = String(bytes: response, encoding: .utf8) {
+            os_log("%{public}@", log: log, type: .default, msg)
+        }
+        return response
     }
 
 }

Sources/LanguageServer/main.swift

@@ -26,8 +26,6 @@ dataAvailable = NotificationCenter.default.addObserver(forName: .NSFileHandleDat
     let requests = AnySequence<Data>() { iterator }
 
     for requestBuffer in requests {
-        let str = String(data: buffer, encoding: .utf8) ?? "Expected UTF-8 encoding."
-
         do {
             let request = try Request(requestBuffer)
             let response = handle(request)

Sources/LanguageServerProtocol/Types/RequestIterator.swift

@@ -7,7 +7,10 @@
 //
 
 import Foundation
+import os.log
 
+@available(macOS 10.12, *)
+private let log = OSLog(subsystem: "me.lovelett.langserver-swift", category: "RequestIterator")
 fileprivate let terminatorPattern = Data(bytes: [0x0D, 0x0A, 0x0D, 0x0A]) // "\r\n\r\n"
 
 public struct RequestIterator {
@@ -21,7 +24,14 @@ public struct RequestIterator {
     }
 
     mutating public func append(_ data: Data) {
+        if #available(macOS 10.12, *) {
+            os_log("Adding %{iec-bytes}d to the request buffer which has %{iec-bytes}d", log: log, type: .default, data.count, iterator.data.count)
+        }
         iterator.append(data)
+        if #available(macOS 10.12, *), let new = String(bytes: data, encoding: .utf8), let buffer = String(bytes: iterator.data, encoding: .utf8) {
+            os_log("Added: %{public}@", log: log, type: .default, new)
+            os_log("Buffer: %{public}@", log: log, type: .default, buffer)
+        }
     }
 
 }