Xtext offers the user to implement an Xtend Class that implements the org.eclipse.xtext.generator.IGenerator Interface. By Default this Generator is called by the Builder through a org.eclipse.xtext.builder.IXtextBuilderParticipant when saving the file. But what to do if I want to call the Generator explicitely through a context menu entry on the file as shown in the screenshot below? This will be shown in the Following example.
Grammar & IGenerator
We first start with writing the Grammar and after generating the language we implement the Generator Stub Xtext created for us.
grammar org.xtext.example.mydsl.MyDsl with org.eclipse.xtext.common.Terminals
generate myDsl "http://www.xtext.org/example/mydsl/MyDsl"
Model:
greetings+=Greeting*;
Greeting:
'Hello' name=ID ('from' from=[Greeting])?'!';
package org.xtext.example.mydsl.generator
import org.eclipse.emf.ecore.resource.Resource
import org.eclipse.xtext.generator.IGenerator
import org.eclipse.xtext.generator.IFileSystemAccess
import org.xtext.example.mydsl.myDsl.Greeting
import static extension org.eclipse.xtext.xtend2.lib.ResourceExtensions.*
class MyDslGenerator implements IGenerator {
override void doGenerate(Resource resource, IFileSystemAccess fsa) {
for (g : resource.allContentsIterable.filter(typeof(Greeting))) {
fsa.generateFile(g.name+".txt",'''
Hello «g.name» «IF g.from != null»from «g.from.name»«ENDIF»!
''')
}
}
}
Disabling the IBuilderParticipant
Then we go to the UI Projects plugin.xml and disable the default registration of an IXtextBuilderParticipant
<!--
<extension
point="org.eclipse.xtext.builder.participant">
<participant
class="org.xtext.example.mydsl.ui.MyDslExecutableExtensionFactory:org.eclipse.xtext.builder.IXtextBuilderParticipant">
</participant>
</extension>
-->
Then we setup the context menu with Eclipse means
<extension
point="org.eclipse.ui.handlers">
<handler
class="org.xtext.example.mydsl.ui.MyDslExecutableExtensionFactory:org.xtext.example.mydsl.ui.handler.GenerationHandler"
commandId="org.xtext.example.mydsl.ui.handler.GenerationCommand">
</handler>
</extension>
<extension
point="org.eclipse.ui.commands">
<command name="Generate Code"
id="org.xtext.example.mydsl.ui.handler.GenerationCommand">
</command>
</extension>
<extension point="org.eclipse.ui.menus">
<menuContribution locationURI="popup:org.eclipse.jdt.ui.PackageExplorer">
<command
commandId="org.xtext.example.mydsl.ui.handler.GenerationCommand"
style="push">
<visibleWhen
checkEnabled="false">
<iterate>
<adapt type="org.eclipse.core.resources.IResource">
<test property="org.eclipse.core.resources.name"
value="*.mydsl"/>
</adapt>
</iterate>
</visibleWhen>
</command>
</menuContribution>
</extension>
Implementing the Handler / Calling the Generator
The last thing we have to do is to call the IGenerator from the handler class.
this could look like
public class GenerationHandler extends AbstractHandler implements IHandler {
@Inject
private IGenerator generator;
@Inject
private Provider<EclipseResourceFileSystemAccess> fileAccessProvider;
@Inject
IResourceDescriptions resourceDescriptions;
@Inject
IResourceSetProvider resourceSetProvider;
@Override
public Object execute(ExecutionEvent event) throws ExecutionException {
ISelection selection = HandlerUtil.getCurrentSelection(event);
if (selection instanceof IStructuredSelection) {
IStructuredSelection structuredSelection = (IStructuredSelection) selection;
Object firstElement = structuredSelection.getFirstElement();
if (firstElement instanceof IFile) {
IFile file = (IFile) firstElement;
IProject project = file.getProject();
IFolder srcGenFolder = project.getFolder("src-gen");
if (!srcGenFolder.exists()) {
try {
srcGenFolder.create(true, true,
new NullProgressMonitor());
} catch (CoreException e) {
return null;
}
}
final EclipseResourceFileSystemAccess fsa = fileAccessProvider.get();
fsa.setOutputPath(srcGenFolder.getFullPath().toString());
URI uri = URI.createPlatformResourceURI(file.getFullPath().toString(), true);
ResourceSet rs = resourceSetProvider.get(project);
Resource r = rs.getResource(uri, true);
generator.doGenerate(r, fsa);
}
}
return null;
}
@Override
public boolean isEnabled() {
return true;
}
}
Give it a try
We start a runtime app, create a bunch of model files that refernce each other,
try the genenerator – and hey – it works.
And how if i want to call the generator from the context menu of the open editor
I register the command for the editor and write a Handler like this one
<extension point="org.eclipse.ui.menus">
<menuContribution locationURI="popup:#TextEditorContext?after=additions">
<command
commandId="org.xtext.example.mydsl.ui.handler.GenerationCommand"
style="push">
<visibleWhen
checkEnabled="false">
<reference
definitionId="org.xtext.example.mydsl.MyDsl.Editor.opened">
</reference>
</visibleWhen>
</command>
</menuContribution>
</extension>
public class GenerationHandler extends AbstractHandler implements IHandler {
@Inject
private IGenerator generator;
@Inject
private Provider<EclipseResourceFileSystemAccess> fileAccessProvider;
@Inject
IResourceDescriptions resourceDescriptions;
@Inject
IResourceSetProvider resourceSetProvider;
@Override
public Object execute(ExecutionEvent event) throws ExecutionException {
IEditorPart activeEditor = HandlerUtil.getActiveEditor(event);
IFile file = (IFile) activeEditor.getEditorInput().getAdapter(IFile.class);
if (file != null) {
IProject project = file.getProject();
IFolder srcGenFolder = project.getFolder("src-gen");
if (!srcGenFolder.exists()) {
try {
srcGenFolder.create(true, true,
new NullProgressMonitor());
} catch (CoreException e) {
return null;
}
}
final EclipseResourceFileSystemAccess fsa = fileAccessProvider.get();
fsa.setOutputPath(srcGenFolder.getFullPath().toString());
if (activeEditor instanceof XtextEditor) {
((XtextEditor)activeEditor).getDocument().readOnly(new IUnitOfWork<Boolean, XtextResource>() {
@Override
public Boolean exec(XtextResource state)
throws Exception {
generator.doGenerate(state, fsa);
return Boolean.TRUE;
}
});
}
}
return null;
}
@Override
public boolean isEnabled() {
return true;
}
}
Update: in newer Xtext Versions configure the File System Access as follows
fsa.setOutputPath("src-gen");
fsa.setProject(project);
fsa.setMonitor(new NullProgressMonitor());
