Karsten Thoms & Holger Schill

Recipes to build Code Generators for Non-Xtext Models with Xtend_____

________

Templates a la Xtend

Minimal Generator with JSON Model

Generator with Xtext Framework on EMF UML Model

3,50€

8,70€

16,20€

Template Expressions

(aka String Concatenation)

GreyspaceShows what makes it in the generated code

Makes readable templates possible

GreyspaceIndentation of call is taken into account

Model Navigation

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

filter

map

fold

sortBy

head

reduce

Build your own! It’s just library!Higher-Order Functions

ExtensionsAdd new API where you need it

Extensions

Extensions

Dynamic Dispatch

Dynamic Dispatch

Dynamic DispatchGenerated Java

Dynamic Dispatch

IDE Support

Extract methodRenameRefactoring

Content AssistQuick Assist

Formatting

Type Hierarchy

Call Hierarchy

Syntax Coloring

Outline

etc…

Debugging

Modularization

Feature Models?

AOP?

Dependency Injection

’s easy usage

No Engine needed

No ContextObject needed

’s easy usage

No Engine needed

No ContextObject needed

At the end it’s feels like using Java

but better…

Write readable and understandable codeShould be self-evident but …

Write readable and understandable codeShould be self-evident but …

Make use of dependency injection

Guice

Use incremental code generators

Use incremental code generatorsFast turnarounds

Use incremental code generatorsFast turnarounds

Just having it run on a server is no option

The m - 1 Problem

BeanBeanObject

Reso

urce

Configuration File

BeanBeanObject

Reso

urce

BeanBeanObject

Reso

urce

ResourceSet

ResourceSet

The m - 1 Problem

BeanBeanObject

Reso

urce

Configuration File

BeanBeanObject

Reso

urce

BeanBeanObject

Reso

urce

It’s worth to think about a merging strategy

Incremental code generators in Xtext// generator APIfragment = generator.GeneratorFragment auto-inject {}

Incremental code generators in Xtext// generator APIfragment = 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(', '))

}}

Incremental code generators in Xtext// generator APIfragment = 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

Incremental code generators in Xtext// generator APIfragment = 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

more than just a code-gen language…

http://www.xtend-lang.org/

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

Generator Process

1.Read Models

2.Validation

3.Execute Templates

4.Write to File-System

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

JSON Input

Meta Classes

Xtend Code Template

Main CLI Class

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

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

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

Xtend Code Template

Guice Runtime Module

Guice Runtime Module

Guice Runtime Module

Guice Runtime Module

!!

Guice Runtime Module

Guice Runtime Module

Standalone Setup

Generator Workflow

Generator Workflow

UI Integration

plugin.xml

Extension Factory

UI Builder Integration

Generate on file save

Build Integration

Import Organizing

Bon Appetit!

KEEP INFORMED

itemis.com / Blogs / Xtext

@kthoms

@holgerschill

@itemis

@chrdietrich

@franzbecker_io

Find the examples here: https://github.com/kthoms/xtend-codegen-examples