I have been a user of Xtext from its early days back at openArchitectureWare. With Xtexts move to Eclipse I became more and more a power user of Xtext, in particular answering a ton of questions in the Xtext forum and building fancy DSLs in multiple (customer) projects. In 2016 I started committing regularly and in 2018 I also started leading Xtext as Co-Lead. In the past years I tried my very best to keep Xtext alive and maintained as part of my job and beyond. And I kept doing so until today. But now the time has come to set out for new shores: I will be leaving itemis end of the month and with the job change Xtext no longer will be part of my day job.
What impact will this have for Xtext?
- I won’t drop the pen immediately, but as Xtext will be pure spare time joy, the time i will be able to invest will be heavily reduced.
- Responsiveness to Questions/Bugs in Github or Forum will be slower
- Xtext will rely more on the community / Xtext using companies for bugfixes and support for new features like support for new Java versions or dependency bumps / adaption of platform/jdt changes.
- As in the past you all are invited to contribute.
- If you have any questions feel free to approach me.
What will I do in the future?
- I can’t talk about that yet, but I will stay participating the modeling-sphere.
Final words:
I want to thank itemis and specially Holger for giving me the opportunity to work on Xtext and Sebastian for the good sparring we had and for all the effort he spent supporting me, as well as the other Xtext team members at itemis, other committers and the community for the good cooperation & time we had.
This is a short blog on how to do code coverage reports with Xtend.
Imagine you have some nice Xtend Code like this one
package demo
class Demo {
def doSomething() {
return 1
}
def doSomethingElse() {
return 2
}
}
wouldn’t it be nice to have code coverage like
Using the xtend-maven-plugin in version 2.9.0+ this works more or less out of the box
<plugin>
<groupId>org.eclipse.xtend</groupId>
<artifactId>xtend-maven-plugin</artifactId>
<version>2.9.0</version>
<executions>
<execution>
<goals>
<goal>compile</goal>
<goal>testCompile</goal>
<goal>xtend-install-debug-info</goal>
<goal>xtend-test-install-debug-info</goal>
</goals>
<configuration>
<xtendAsPrimaryDebugSource>true</xtendAsPrimaryDebugSource>
<outputDirectory>${project.build.directory}/xtend-gen/main</outputDirectory>
<testOutputDirectory>${project.build.directory}/xtend-gen/test</testOutputDirectory>
<writeTraceFiles>true</writeTraceFiles>
</configuration>
</execution>
</executions>
</plugin>
The interesting - new - parts are the goals xtend-install-debug-info and xtend-test-install-debug-info as well as the configuration xtendAsPrimaryDebugSource.
Here is my complete sample pom
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>demo</groupId>
<artifactId>demo</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<compilerId>eclipse</compilerId>
<source>1.8</source>
<target>1.8</target>
<optimize>true</optimize>
</configuration>
<dependencies>
<dependency>
<groupId>org.codehaus.plexus</groupId>
<artifactId>plexus-compiler-eclipse</artifactId>
<version>2.6</version>
<scope>runtime</scope>
</dependency>
</dependencies>
</plugin>
<plugin>
<groupId>org.jacoco</groupId>
<artifactId>jacoco-maven-plugin</artifactId>
<version>0.7.5.201505241946</version>
<executions>
<!-- Prepares the property pointing to the JaCoCo runtime agent which
is passed as VM argument when Maven the Surefire plugin is executed. -->
<execution>
<id>pre-unit-test</id>
<goals>
<goal>prepare-agent</goal>
</goals>
<configuration>
<!-- Sets the path to the file which contains the execution data. -->
<destFile>${project.build.directory}/coverage-reports/jacoco-ut.exec</destFile>
<!-- Sets the name of the property containing the settings for JaCoCo
runtime agent. -->
<propertyName>surefireArgLine</propertyName>
</configuration>
</execution>
<!-- Ensures that the code coverage report for unit tests is created
after unit tests have been run. -->
<execution>
<id>post-unit-test</id>
<phase>test</phase>
<goals>
<goal>report</goal>
</goals>
<configuration>
<!-- Sets the path to the file which contains the execution data. -->
<dataFile>${project.build.directory}/coverage-reports/jacoco-ut.exec</dataFile>
<!-- Sets the output directory for the code coverage report. -->
<outputDirectory>${project.reporting.outputDirectory}/jacoco-ut</outputDirectory>
</configuration>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
<version>2.15</version>
<configuration>
<!-- Sets the VM argument line used when unit tests are run. -->
<argLine>${surefireArgLine}</argLine>
<!-- Skips unit tests if the value of skip.unit.tests property is true -->
<skipTests>${skip.unit.tests}</skipTests>
<!-- Excludes integration tests when unit tests are run. -->
<excludes>
<exclude>**/IT*.java</exclude>
</excludes>
</configuration>
</plugin>
<plugin>
<groupId>org.eclipse.xtend</groupId>
<artifactId>xtend-maven-plugin</artifactId>
<version>2.9.0</version>
<executions>
<execution>
<goals>
<goal>compile</goal>
<goal>testCompile</goal>
<goal>xtend-install-debug-info</goal>
<goal>xtend-test-install-debug-info</goal>
</goals>
<configuration>
<xtendAsPrimaryDebugSource>true</xtendAsPrimaryDebugSource>
<outputDirectory>${project.build.directory}/xtend-gen/main</outputDirectory>
<testOutputDirectory>${project.build.directory}/xtend-gen/test</testOutputDirectory>
<writeTraceFiles>true</writeTraceFiles>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
<dependencies>
<dependency>
<groupId>org.eclipse.xtend</groupId>
<artifactId>org.eclipse.xtend.lib</artifactId>
<version>2.9.0</version>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.11</version>
</dependency>
</dependencies>
</project>
Cross References are a often used concept in Xtext. They ususally work like this
Model:
definitions+=Definition*
usages+=Usage*
;
Definition:
"define" name=ID
;
Usage:
"use" definition=[Definition]
;
They can be used in the model like this
but what if i want to write something like
define "This is a Thing"
use "This is a Thing"
well the definition part is easily changed
Definition:
"define" name=STRING
;
But what about the usage part?
well it is quite easy as well. refName=[Type] is short for refName=[Type|ID] which means ‘Refererence a Type and parse an ID. So to use another Terminal or Data Type Rule we change it to refName=[Type|RULENAME]
Usage:
"use" definition=[Definition|STRING]
;
Now the cross refs are working fine. but if we try the editor we find out what autoedit and content assist disturb each other. We type " and auto edit gets us to “|”. If we now type Crtl+Space for content assist we finally get “This is a Thing”" with an extra " at the end.
To avoid this we have to tweak the proposal provider a bit.
package org.xtext.example.mydsl.ui.contentassist
import org.xtext.example.mydsl.ui.contentassist.AbstractMyDslProposalProvider
import org.eclipse.emf.ecore.EObject
import org.eclipse.xtext.Assignment
import org.eclipse.xtext.ui.editor.contentassist.ContentAssistContext
import org.eclipse.xtext.ui.editor.contentassist.ICompletionProposalAcceptor
import org.eclipse.xtext.ui.editor.contentassist.ICompletionProposalAcceptor.Delegate
import org.eclipse.jface.text.contentassist.ICompletionProposal
import org.eclipse.xtext.ui.editor.contentassist.ConfigurableCompletionProposal
class MyDslProposalProvider extends AbstractMyDslProposalProvider {
override completeUsage_Definition(EObject model, Assignment assignment, ContentAssistContext context, ICompletionProposalAcceptor acceptor) {
super.completeUsage_Definition(model, assignment, context, new StringProposalDelegate(acceptor, context))
}
static class StringProposalDelegate extends Delegate {
ContentAssistContext ctx
new(ICompletionProposalAcceptor delegate, ContentAssistContext ctx) {
super(delegate)
this.ctx = ctx
}
override accept(ICompletionProposal proposal) {
if (proposal instanceof ConfigurableCompletionProposal) {
val endPos = proposal.replacementOffset + proposal.replacementLength
if (ctx.document != null && ctx.document.length > endPos) {
// We are not at the end of the file
if ("\"" == ctx.document.get(endPos, 1)) {
proposal.replacementLength = proposal.replacementLength-1
proposal.replacementString = proposal.replacementString.substring(0,proposal.replacementString.length-1)
}
}
}
super.accept(proposal)
}
}
}
what we basically do is detecting the situation and remove the extra "
If you have a DSL that describes structure (e.g. like an Entity DSL) you often need to “walk” on this structure using dot/path-expressions.
Let us asume we have a grammar like
Model:
entities+=Entity*
;
Entity:
"entity" name=ID "{"
features+=Feature*
"}"
;
Feature:
Attribute | Reference
;
Attribute:
"attr" name=ID ":" type=DataType
;
enum DataType:
string | int
;
Reference:
"ref" name=ID ":" type=[Entity]
;
and a model like
entity A {
attr a1 : int
attr a2 : string
ref b : B
ref c : C
}
entity B {
attr b1 : string
attr b2 : string
ref a : A
ref c : C
}
entity C {
attr c1 : string
attr c2 : int
}
and want to have expressions like
use A.b.b2
use A.b.c.c1
use A.a1
use A.b.a.a1
but how to do this with Xtext?
there are several possibility but the following was working well in my usecase:
Model:
entities+=Entity*
usages+=Usage*
;
Usage:
"use" ref=DotExpression
;
DotExpression returns Ref:
EntityRef ({DotExpression.ref=current} "." tail=[Feature])*
;
EntityRef returns Ref:
{EntityRef} entity=[Entity]
;
a bit of scoping
class MyDslScopeProvider extends AbstractDeclarativeScopeProvider {
def IScope scope_DotExpression_tail(DotExpression exp, EReference ref) {
val head = exp.ref;
switch (head) {
EntityRef : Scopes::scopeFor(head.entity.features)
DotExpression : {
val tail = head.tail
switch (tail) {
Attribute : IScope::NULLSCOPE
Reference : Scopes::scopeFor(tail.type.features)
default: IScope::NULLSCOPE
}
}
default: IScope::NULLSCOPE
}
}
}
and it works fine.
as an additional note: the ast of the expressions look like
One of my Colleagues recently gave me a hint on PlantUML which is a nice tool to create Graphviz based UML diagrams from a textual input. This blogpost describes how to include PlantUML into Xtext to generate Visualizations from textual models on the fly.
Here is the DSL from
Domainmodel :
elements += Type*
;
Type:
DataType | Entity
;
DataType:
'datatype' name = ID
;
Entity:
'entity' name = ID ('extends' superType = [Entity])? '{'
features += Feature*
'}'
;
Feature:
many?='many'? name = ID ':' type = [Type]
;
The target is to take an input model like
datatype String
entity A {
many names : String
c : C
}
entity B {
something : String
many myA : A
}
entity C {
}
An generate a nice Diagram like
To make the integration easy we generate the png using the existing Builder/Generator infrastructure
So here is the text input for PlantUML we need to generate
@startuml
class A {
List<String> names
}
A o-- C : c
class B {
String something
}
B o-- "*" A : myA
class C {
}
@enduml
and here the generator that does the conversion and feeds Plantuml
class MyDslGenerator implements IGenerator {
override void doGenerate(Resource resource, IFileSystemAccess fsa) {
val filename = resource.URI.lastSegment
for (dm : resource.contents.filter(typeof(Domainmodel))) {
val plantUML = dm.toPlantUML.toString
if (fsa instanceof IFileSystemAccessExtension3) {
val out = new ByteArrayOutputStream()
new SourceStringReader(plantUML).generateImage(out)
(fsa as IFileSystemAccessExtension3).generateFile(filename + ".png",
new ByteArrayInputStream(out.toByteArray))
} else {
fsa.generateFile(filename + ".txt", plantUML)
}
}
}
def dispatch CharSequence toPlantUML(Domainmodel it) '''
@startuml
«FOR e : elements.filter(typeof(Entity))»
«e.toPlantUML»
«ENDFOR»
@enduml
'''
def dispatch CharSequence toPlantUML(Entity it) '''
class «name» {
«FOR f : features.filter[type instanceof DataType]»
«IF f.many»List<«f.type.name»>«ELSE»«f.type.name»«ENDIF» «f.name»
«ENDFOR»
}
«FOR f : features.filter[type instanceof Entity]»
«name» o-- «IF f.many»"*" «ENDIF» «f.type.name» : «f.name»
«ENDFOR»
'''
}
To get PlantUML into the Classpath we add the jar to the project
and add it via the Manifest.MF file
Bundle-ClassPath: .,
lib/plantuml.jar
