OpenSource Swift

"Improving Your Developper Experience With Open-Source Swift " shows how you can download and compile the Swift project and start hacking inside it's internals for some fun & benefits in Xcode.

Presented on Sept 21st, 2018 at FrenchKit Conference (www.frenchkit.fr)
Video at www.youtube.com/watch?v=olS5w9fBxog

Transcript

1. I m p r o v i n g y o u r Developer Experienc e with Open-Source Swift Dimitri Dupuis-Latour @dupuislatour 2018
2. Story
3. Xcode in Xcode Xcode.xcodeproj
4. Xcode in Xcode
5. Xcode in Xcode 1
6. Swift
7. Open-Source Swift
8. Open-Source Swift
9. Open-Source Swift
10. How ?
11. Toolchain
12. Toolchain
13. Toolchain
14. How ?
15. https://github.com/apple/swift README git clone 1 repository ./swift/utils/update-checkout 14 repositories 2GB source code ./swift/utils/build-script ≈1 hour (full build in debug) ≈70 GB of build artifacts
16. Swift checkout
17. Swift checkout
18. Swift checkout
19. Swift checkout
20. Compiler 
 aka ‘lib’
21. Compiler 
 aka ‘lib’ AST SourceKit Fixits Warnings Refactoring Engine
22. Compiler 
 aka ‘lib’ AST SourceKit Fixits Warnings Refactoring Engine
23. Refactoring Engine
24. Refactoring Engine Xcode SourceKit
25. Adding a new Refactoring « Frenchify »
26. Refactoring Engine RefactoringKinds.def : CURSOR_REFACTORING(Frenchify, "Frenchify", frenchify.expr)
27. Refactoring Engine RefactoringKinds.def : CURSOR_REFACTORING(Frenchify, "Frenchify", frenchify.expr) Refactoring.cpp : bool RefactoringActionFrenchify::isApplicable(ResolvedCursorInfo CursorInfo) { return true; }
28. Refactoring Engine RefactoringKinds.def : CURSOR_REFACTORING(Frenchify, "Frenchify", frenchify.expr) Refactoring.cpp : bool RefactoringActionFrenchify::isApplicable(ResolvedCursorInfo CursorInfo) { return true; } bool RefactoringActionFrenchify::performChange() { return false; // Return true if code change aborted. }
29. Refactoring Engine RefactoringKinds.def : CURSOR_REFACTORING(Frenchify, "Frenchify", frenchify.expr) Refactoring.cpp : bool RefactoringActionFrenchify::isApplicable(ResolvedCursorInfo CursorInfo) { return true; } bool RefactoringActionFrenchify::performChange() { EditConsumer.insert(SM, Cursor.TrailingExpr->getStartLoc(), "Le "); return false; // Return true if code change aborted. }
30. Refactoring Engine RefactoringKinds.def : CURSOR_REFACTORING(Frenchify, "Frenchify", frenchify.expr) Refactoring.cpp : bool RefactoringActionFrenchify::isApplicable(ResolvedCursorInfo CursorInfo) { return true; } bool RefactoringActionFrenchify::performChange() { EditConsumer.insert(SM, Cursor.TrailingExpr->getStartLoc(), "Le "); EditConsumer.insertAfter(SM, Cursor.TrailingExpr->getEndLoc(), " "); return false; // Return true if code change aborted. }
31. Xcode
32. Le Xcode
33. https://swift.org/blog/swift-local-refactoring More Examples
34. "But I am not a compiler engineer !" — Joe, average iOS developper
35. https://github.com/apple/swift
36. Standard Library 
 aka ‘stdlib’
37. Bool.toggle() Swift 4.2, Chris Eidhof extension Bool { @_inlineable /// Toggles the value of the Boolean. /// /// Calling this method sets the variable to `true` if it was `false`, /// and sets it to `false` if it was `true`. For example: /// /// var bools = [true, false] /// /// bools[0].toggle() /// // bools now contains [false, false] public mutating func toggle() { self = !self } } [SE-0199] Adding toggle to Bool
38. Dictionary.compactMapValues() Swift 5 /// Returns a new dictionary containing the keys of this dictionary with the /// values transformed by the given closure. /// - Parameter transform: A closure that transforms a value. `transform` /// accepts each value of the dictionary as its parameter and returns a /// transformed value of the same or of a different type. /// - Returns: A dictionary containing the keys and transformed values of /// this dictionary. @inlinable // FIXME(sil-serialize-all) public func compactMapValues<T>( _ transform: (Value) throws -> T? ) rethrows -> Dictionary<Key, T> { return try self.reduce(into: [Key: T](), { (result, x) in if let value = try transform(x.value) { result[x.key] = value } }) } [SE-0218] Introduce compactMapValues to Dictionary
39. Sequence.countWhere() Swift 5 [SE-0220] count(where:) extension Sequence { /// Returns the number of elements in the sequence that satisfy the given /// predicate. /// /// […] /// - Parameter predicate: A closure that takes each element of the sequence /// as its argument and returns a Boolean value indicating whether /// the element should be included in the count. /// - Returns: The number of elements in the sequence that satisfy the given /// predicate. @inlinable public func count( where predicate: (Element) throws -> Bool ) rethrows -> Int { var count = 0 for e in self { if try predicate(e) { count += 1 } } return count } }
40. Let’s talk !