Bring back multi-threading

Author: max-leuthaeuser

Sources/SwiftAstGenLib/SwiftAstGenerator.swift

@@ -5,6 +5,7 @@ public class SwiftAstGenerator {
 	private var srcDir: URL
 	private var outputDir: URL
 	private var prettyPrint: Bool
+	private let availableProcessors = ProcessInfo.processInfo.activeProcessorCount
 
 	public init(srcDir: URL, outputDir: URL, prettyPrint: Bool) throws {
 		self.srcDir = srcDir
@@ -43,13 +44,13 @@ public class SwiftAstGenerator {
 				.appendingPathExtension("json")
 			let outfileDirUrl = outFileUrl.deletingLastPathComponent()
 
-			if !FileManager.default.fileExists(atPath: outfileDirUrl.path) {
+			do {
 				try FileManager.default.createDirectory(
 					atPath: outfileDirUrl.path,
 					withIntermediateDirectories: true,
 					attributes: nil
 				)
-			}
+			} catch {}
 
 			try astJsonString.write(
 				to: outFileUrl,
@@ -64,6 +65,11 @@ public class SwiftAstGenerator {
 	}
 
 	private func iterateSwiftFiles(at url: URL) {
+		let queue = OperationQueue()
+		queue.name = "SwiftAstGen"
+		queue.qualityOfService = .userInitiated
+		queue.maxConcurrentOperationCount = availableProcessors
+
 		if let enumerator = FileManager.default.enumerator(
 			at: url,
 			includingPropertiesForKeys: [.isRegularFileKey],
@@ -73,11 +79,15 @@ public class SwiftAstGenerator {
 	            if fileAttributes.isRegularFile! && fileURL.pathExtension == "swift" {
 	            	let relativeFilePath = fileURL.relativePath(from: srcDir)!
 	            	if !ignoreDirectory(name: "/\(relativeFilePath)") {
-	            		parseFile(fileUrl: fileURL)
+	            		queue.addOperation {
+	            			self.parseFile(fileUrl: fileURL)
+	            		}
 	            	}
 	            }
 		    }
 		}
+
+		queue.waitUntilAllOperationsAreFinished()
 	} 
 
 	public func generate() throws {