Dealing with KSP in Common Code

How to use KSP (experimental) with Kotlin Multiplatform for both iOS and Android

1. Dealing With KSP in Common Code for Android and iOS Anna Zharkova Lead Mobile developer
2. Introduction • Mobile developer since 2013 • Lead Mobile developer in «Usetech software» . • Native mobile development, iOS and Android (Swift/Objective-C, Kotlin/Java) cross-platform mobile development (Xamarin, Kotlin multiplatform) • Leading mobile team. Mentorship • Public speaking (Mobius Moscow 2020, AppsLive 2020) • Tutor in Otus (iOS advanced) • Writing articles about mobile development (especially iOS and KMM ) • Women Techmaker Ambassador since 2021 • Kotlin GDE (2021) 2
3. Goals. Today discuss: • Kotlin Symbol Processing, how it works • KSP in practice. Simplify Dependency Injection • Kotlin Multiplatform and its conception. Using KSP with common code • KSP with iOS. Supporting unsupported 3
4. Kotlin Symbol Processing 4 First experimental release in 2020 Announced by Google in 10 Feb 2021 Compatible with Kotlin (since 1.4.30) Good for multiplatform
5. Kotlin Symbol Processing. Purpose 5 • Build lightweight Kotlin compiler plugins • Create annotation processors
6. Annotation processing. Purpose 6 • Analyze code • Generate common code for some purposes • Simplify abstractions and etc
7. Annotation processing. Basis 7 Register annotation processing List unprocessed source files with annotation Run processors Any Processors for them? Compile
8. KAPT (Kotlin annotation processing tool)1 8 Kotlin KAPT Data for APT Annotation processor (kotlin wrapper) Java bytecode Annotation processor
9. KAPT (Kotlin annotation processing tool) 2/3 9 Kotlin KAPT AST for JAVA stub Javac Java classes JSR 269
10. KAPT vs KSP 10 • KAPT generates Java code • Kotlin compiler has to generate Java stubs before the compilation. • More time • More code
11. Why KSP better 11 PURE FASTER COMPATIBILITY Read Kotlin AST No stubs Support Java code
12. Kotlin symbol processing. How it works 12 Annotation Processor -> Symbol processor
13. Kotlin symbol processing. How it works 13 Provider should be declared as resource
14. Kotlin symbol processing. How it works 14 Resolver – to get data for specific case
15. Kotlin symbol processing. How it works 15 KSP uses reflection to get info about types and components.
16. Kotlin symbol processing. How it works 16 1. Processors read and analyze source programs and resources. 2. Processors generate code or other forms of output. 3. Generated code is compiled together with sources.
17. Kotlin poet 17 Kotlin and Java API for generating .kt source files https://square.github.io/kotlinpoet/
18. Create our own annotation processing 18
19. Kotlin Symbol Processing. Limitations 19 • Processors cannot modify existed code • Generates new files • Strong dependency on JVM at moment • Experimental feature (not recommended to use in production) • Not enough documentation for different cases
20. Ready-made solutions 20 Koin Compiler playground (my sample was inspired with it) https://github.com/InsertKoinIO/koin-compiler- playground
21. Ready-made solutions 21 Easy and nice KSP Sample https://github.com/SeongUgJung/KspSample
22. Manual dependency solution 22 Android part for Multiplatform-DI solution https://github.com/anioutkazharkova/kmm-di-sample https://github.com/anioutkazharkova/di-multiplatform-lib Mulitplatform DI core (KMM) Android Native app
23. DI Solution 23 DIContainer -> Resolver Scopes define the conditions DIContainer Resolver Scope Scope Scope Resolve Reference<T> -> T? <T> ReferenceReg<T> MainScopeHolder
24. Manual dependency solution 24 What we get in start https://github.com/anioutkazharkova/kmm-di- sample https://github.com/anioutkazharkova/di- multiplatform-lib
25. Adding annotations 25 Scopes - > scope annotations Container - > containers annotations
26. KSP DI Solution 26 Mulitplatform DI core (KMM) Android Native app Mulitplatform DI core (KMM) KSP Compiler KSP Annotations
27. KSP DI Solution 27 KSP Compiler depends on symbol-processing-api
28. KSP DI Solution 28 KSP Compiler depends on symbol-processing-api
29. KSP DI Solution 29 Don’t forget Kotlin Poet
30. KSP DI Solution 30 DI Code Symbol Processor Scanners (Visitors) Code generator Generated_data.kt Found data Search request Found and processed data (tree)
31. Custom DI Symbol provider 31
32. Custom DI Symbol provider 32
33. KSP Resolver 33 We need to get annotated symbols to analyze them
34. KSP Resolver 34
35. Generate file with Kotlin Poet 35 That’s ok to use hardcoded string in template
36. Generate file with Kotlin Poet 36 Put all your stuff in template
37. Let’s build! 37 Sample compilation output
38. Generated DI solution 38 What we got as result https://github.com/anioutkazharkova/ksp-di- playground
39. Generated DI solution 39 What we got as result https://github.com/anioutkazharko va/ksp-di-playground
40. Use it with code 40 Connect and check https://github.com/anioutkazharkova/ks p-di-playground
41. Use it with code 41 Connect and check https://github.com/anioutkazharkova/ks p-di-playground
42. Let’s use in multiplatform project 42
43. Kotlin Multiplatform 43
44. Kotlin Multiplatform 44 • SDK, not framework • JVM for Android and LLVM for iOS • Total sharing (almost)
45. Every platform needs its Kotlin 45 Kotlin Common Kotlin JVM Kotlin JS Kotlin Native
46. Multiplatform – DI 46 Mulitplatform DI core (KMM) Android Native app iOS Native app Shared module KMM
47. Dealing with KSP in multiplatform 47 KSP (JVM library) Common Main JVM main/Android main Shared module
48. Dealing with KSP in multiplatform 48 KSP (JVM library) Common Main JVM main/Android main Shared module
49. KSP and Kotlin/Native problem 49 • KSP supports Kotlin JS/JVM • Kotlin/Native will be supported in future (official plans)
50. KSP and Kotlin/Native problem 50
51. KSP and Kotlin/Native problem 51 • KSP supports Kotlin JS/JVM • Kotlin/Native will be supported in future (official plans) • Bunch of info about unsupported targets L
52. Dealing with KSP in multiplatform 52 • KSP could be used in multiplatform project • To use library with multiplatform it should be multiplatform
53. Dealing with KSP in multiplatform 53 :ksp-di-compiler :ksp-di-shared
54. Dealing with KSP in multiplatform 54 Set in KSP shared compiler just jvm target
55. Multiplatform – DI - KSP 55 Mulitplatform DI core (KMM) Android Native app iOS Native app Shared module KMM :ksp-di-shared Mulitplatform DI core (KMM)
56. Dealing with KSP in multiplatform 56 Connect to shared module of app Use dependencies section
57. KSP and Kotlin/Native problem 57 • KSP supports Kotlin JS/JVM • Kotlin/Native will be supported in future (official plans)
58. Dealing with KSP in multiplatform 58 Files generated!
59. Let’s make it work with iOS 59
60. It will be experimental solution for experimental feature 60
61. KSP and iOS setup 61 Generated file contains code for multiplatform support
62. KSP and iOS setup 62 Multiplatform code should be wrapped into library with source set prior Multiplatform Library Generated common code iOS Native app
63. Setup using generated data 63 Add it to source set for all platforms in shared module
64. KSP DI Multiplatform 64
65. Kotlin symbol processing. Main challenges 65 • Work with multiplatform • Kotlin/Native • Generated files are not used by default • Experimental feature • Not to much documentation for purposes
66. Kotlin compile plugin vs KSP 66 • Analyze Abstract Syntax Tree • Modify existing code • Could be used in Kotlin/Native
67. Kotlin symbol processing. Future and prospects 67 • Make the IDE aware of the generated code. • Support Kotlin Native.
68. Summary. 68 • KSP is faster than KAPT, better performance • KSP is experimental, but still be developed. • Not recommended for production at moment, but could be used for interesting cases • Multiplatform at moment, but doesn’t support Kotlin/Native • Will support Kotlin/Native and multiple round in future
69. Sources 69 • https://github.com/anioutkazharkova/ksp-di-playground • https://github.com/google/ksp#kotlin-symbol-processing-api • https://kotlinlang.org/docs/mobile/home.html • https://github.com/InsertKoinIO/koin-compiler-playground • https://github.com/SeongUgJung/KspSample • https://github.com/FutureMind/koru
70. Thanks for listening! 70 @anioutkajarkova azharkova prettygeeknotes