A tiny code generator to produce a Java "Builder" and fluent API from Ecore models

What can I use this for ?

To code the creation of a model instance leveraging your Java and your IDE, in a dense way.

Example, here applied on the Sirius Web views model to describe a form editor:

	 public FormDescription formWithstatsOfTheCompleteBiblioGraphy = this.m.newFormDescription()
	            .name("Biblio stats")
	            .domainType(this.m.asDomainType(BiblioPackage.eINSTANCE.getBiblio()))
	            .groups(this.m.newGroupDescription()
	                    .name("Global stats")
	                    .displayMode(GroupDisplayMode.LIST)
	                    .semanticCandidatesExpression(this.m.asAQL("self"))
	                    .widgets(this.m.newLabelDescription()
	                            .name("nb publications")
	                            .labelExpression(this.m.asAQL("'number of publications:' + self.eAllContents(biblio::Publication)->size()"))
	                            .style(this.m.newLabelDescriptionStyle()
	                                    .bold(true)
	                                    .build())
	                            .build() ,
	                            this.m.newBarChartDescription()
	                            .name("publications per shelve")
	                            .keysExpression(this.m.asAQL("self.eAllContents(biblio::Shelve)"))
	                            .valuesExpression(this.m.asAQL("self.publications->size()"))
	                            .labelExpression(this.m.asAQL("self.name"))
	                            .style(this.m.newBarChartDescriptionStyle()
	                                    .barsColor("blue")
	                                    .build())
	                            .build())
	                    .build())
	            .build();

It generates a XXXBuilders class where XXX is your Ecore package name, and from there you can create new instances using builders (YYYBuilder where YYY is the EClass name)

It uses JMerge so you are able to customize changing the @generated annotations.

Goals I pursued when trying this

I wanted to be able to:

• to be able to leverage my IDE to search for reference and easily get for instance, "all the colors I used" or "all the AQL expressions I used"
• to have the guarantee that my model is valid once it is built.
• to be able to factorize code which manipulate the model.
• to be able to add convenience methods to guarantee an uniform way to handle my datatype literals.
• to discover easily what sub elements/other types, I should be able to set in an area (not there yet.)
• to be able to add methods to take shortcuts leveraging the view model hierarchy -> doing so in the abstract builder classes.

And all of that while being able to easily deploy that on any project, whatever the IDE is used and with a minimal impact on the software build chain.

What status is this ?

It's only a few hours of work used to prototype and see what could be achieved on Sirius's web view model, so I would expect that it would not work well with other Ecores currently. Also: generated Java formatting is currently not great.

So expect rough edges and most likely the need to adapt the code.

What would be cool ?

A number of things:

• use Ecore documentation annotation for Javadoc.
• make sure it works with JBang for easy launch
• better Java formatting per default.
• ...

How to launch ?

Either through the main() method or through maven which will handle the retrieval of the EMF dependencies (Have a look on the pom.xml)

	<plugin>
		  <groupId>org.codehaus.mojo</groupId>
		  <artifactId>exec-maven-plugin</artifactId>
		  <version>3.1.0</version>
		  <executions>
		    <execution>
		      <id>generate builders classes</id>
		      <phase>package</phase>
		      <goals>
		        <goal>java</goal>
		      </goals>
		    </execution>
		  </executions>
		        <configuration>
                    <executable>java</executable>
                    <mainClass>fr.obeo.dsl.playground.emfcodegen.builder.BuilderGenerator</mainClass>
                    <cleanupDaemonThreads>false</cleanupDaemonThreads>
                    <arguments>
                      <!-- the emf configuration file to use for JMerge -->
                       <argument>file:${project.basedir}/src/main/java/fr/obeo/dsl/playground/emfcodegen/builder/emf-merge.xml</argument>
                       <!-- the genmodel file -->
                       <argument>file:${project.basedir}../path/to/the/file.genmodel</argument>
                       <!-- the output folder file -->
                       <argument>file:${project.basedir}../path/to/the/folder/to/generate/java/code</argument>
                       <!-- package name to use for the generated code -->
                       <argument>fr.obeo.dsl.biblio.app.representationsbuilders.builders.test</argument>
                    </arguments>
                </configuration>
	</plugin>