This talk was given at EclipseCon Europe 2016 on Oct 26th 2016 in Ludwigsburg

1. Karsten Thoms & Holger Schill
Recipes to build
Code Generators for
Non-Xtext
Models
with Xtend_____
________

2. Templates a la Xtend
Minimal Generator
with JSON Model
Generator with
Xtext Framework
on EMF UML Model
3,50€
8,70€
16,20€

4. Template
Expressions
(aka String Concatenation)

5. Greyspace
Shows what makes it in the generated code
Makes readable templates possible

6. Greyspace
Indentation of call is taken into account

7. Model Navigation

8. Model Navigation
val eClasses = myEPackage.EClassifiers.filter(EClass)
val abstractEClasses = eClasses.filter[isAbstract]
val namesOfAbstractClasses = abstractEClasses.map[name]
val commaSeparatedNamesOfAbstractClasses = namesOfAbstractClasses.join(',')
CommaSeparatedNamesOfAbstractClasses
Model Navigation

9. filter
map
fold
sortBy
head
reduce
Build your own! It’s just library!
Higher-Order Functions

10. Extensions
Add new API where you need it

11. Extensions

12. Extensions

13. Dynamic Dispatch

14. Dynamic Dispatch

15. Dynamic Dispatch
Generated Java

16. Dynamic Dispatch

17. IDE Support
Extract method
RenameRefactoring
Content Assist
Quick Assist
Formatting
Type Hierarchy
Call Hierarchy
Syntax Coloring
Outline
etc…
Debugging

18. Modularization

19. Feature Models?

20. AOP?

21. Dependency Injection

22. ’s easy usage
No Engine needed
No ContextObject needed

23. ’s easy usage
No Engine needed
No ContextObject needed
At the end it’s feels like using Java
but better…

24. Write readable and understandable code
Should be self-evident but …

25. Write readable and understandable code
Should be self-evident but …

26. Make use of dependency injection
Guice

27. Use incremental code generators

28. Use incremental code generators
Fast turnarounds

29. Use incremental code generators
Fast turnarounds
Just having it run on a server is no option

30. The m - 1 Problem
BeanBeanObject
Resource
Configuration File
BeanBeanObject
Resource
BeanBeanObject
Resource
ResourceSet

31. ResourceSet
The m - 1 Problem
BeanBeanObject
Resource
Configuration File
BeanBeanObject
Resource
BeanBeanObject
Resource
It’s worth to think about a
merging strategy

32. Incremental code generators in Xtext
// generator API
fragment = generator.GeneratorFragment auto-inject {}

33. Incremental code generators in Xtext
// generator API
fragment = generator.GeneratorFragment auto-inject {}
class MyDslGenerator implements IGenerator {
override void doGenerate(Resource resource, IFileSystemAccess fsa) {
// fsa.generateFile('greetings.txt', 'People to greet: ' +
// resource.allContents
// .filter(typeof(Greeting))
// .map[name]
// .join(', '))
}
}

34. Incremental code generators in Xtext
// generator API
fragment = generator.GeneratorFragment auto-inject {}
class MyDslGenerator implements IGenerator {
override void doGenerate(Resource resource, IFileSystemAccess fsa) {
// fsa.generateFile('greetings.txt', 'People to greet: ' +
// resource.allContents
// .filter(typeof(Greeting))
// .map[name]
// .join(', '))
}
}
Customisable mechanism is taking care to
recompile affected resources

35. Incremental code generators in Xtext
// generator API
fragment = generator.GeneratorFragment auto-inject {}
class MyDslGenerator implements IGenerator {
override void doGenerate(Resource resource, IFileSystemAccess fsa) {
// fsa.generateFile('greetings.txt', 'People to greet: ' +
// resource.allContents
// .filter(typeof(Greeting))
// .map[name]
// .join(', '))
}
}
http://www.eclipse.org/Xtext/documentation/
350_continuous_integration.html
Get Maven integration for free

36. more than just a code-gen language…
http://www.xtend-lang.org/

37. Why „for Non-Xtext
Models“?
• Xtext provides an infrastructure to generate code
from Xtext DSL files
• Proper setup of Guide required
• Default Xtext Guice modules are only suitable for
Xtext DSLs
• Not much code generators for non-Xtext models
known in open source projects

38. Generator Process
1.Read Models
2.Validation
3.Execute Templates
4.Write to File-System

39. 2,1 MB Guava Library
370 kB Xbase/Xtend Library
226 kB JSON Library (Gson)
60 kB CLI Library (JCommander)
4 Metamodel Classes
1 Xtend Code Template
Minimal Generator
with JSON Model

40. JSON Input

41. Meta Classes

42. Xtend Code Template

43. Main CLI Class

45. 1 Xtext Framework
14 MB of Libraries
1 (EMF) UML Model
1 MWE2 Workflow
1 Guice Configuration
1 Standalone Setup
1 Output Configuration
some Xtend Templates
Generator with
Xtext Framework
on EMF UML Model

46. Xtext’s Generator Support
• IGenerator Interface
• MWE components for reading models and executing
the generator
• Dependency Injection support
• Eclipse build integration, Incremental build
• Different file access for plain Java and EFS
• Outlets

47. Generic Resource Service
• Package org.eclipse.xtext.resource.generic contains
support for generic resources
• Requires EMF based models
• Makes resources for non-Xtext based EMF models
available for the Xtext infrastructure
• Index
• compute IResourceDescription
• create IEObjectDescription

48. Xtend Code Template

49. Guice Runtime Module

50. Guice Runtime Module

51. Guice Runtime Module

52. Guice Runtime Module
!
!

53. Guice Runtime Module

54. Guice Runtime Module

55. Standalone Setup

56. Generator Workflow

57. Generator Workflow

58. UI Integration

59. plugin.xml

60. Extension Factory

62. UI Builder Integration
Generate on file save

64. Build
Integration

65. Import
Organizing

66. Bon Appetit!

67. KEEP INFORMED
itemis.com / Blogs / Xtext
@kthoms
@holgerschill
@itemis
@chrdietrich
@franzbecker_io
Find the examples here:
https://github.com/kthoms/xtend-codegen-examples