Workshop On Xtext

Software Installation • You‘ll ﬁnd a CD with the required software on your desk • Unzip the Eclipse distribution matching your OS Windows users: Use a location close to the root directory • Run the Eclipse executable • Choose File -> Import -> Existing projects into workspace • Select Archive ﬁle and choose workspace.zip from the CD

Workshop Moritz Eysholdt, Sebastian Zarnekow, Jan Köhnlein

Moritz Eysholdt Jan Köhnlein Sebastian Zarnekow

What is a Domain Speciﬁc Language (DSL)?

A domain-speciﬁc language (DSL) is a formal, processable language targeting at a speciﬁc viewpoint or aspect of a system.

A domain-specific language (DSL) is a formal, processable language targeting at a specific viewpoint or aspect of a system. Its semantics, flexibility and notation is designed in order to support working with that viewpoint as good as possible.

Why would I want to use a DSL?

GPL vs DSL

Abstraction

Why isn‘t everybody using DSLs?

Complicated Expensive

Isn‘t text a little bit old- fashioned?

} protected String getErrorMessage() { return errorMessage.toString(); } Graphics public boolean isSameStructure(EObject left, EObject right) { counter = 0; return internalIsSameStructure(left, right); } public boolean internalIsSameStructure(EObject left, EObject right) { ++counter; if (!isSameClass(left.eClass(), right.eClass())) { errorMessage.append("Classes are not equal: " + left + " != " + ri return false; } List<EObject> leftChildren = getRelevantChildren(left); List<EObject> rightChildren = getRelevantChildren(right); if(leftChildren.size() != rightChildren.size()) { errorMessage.append("Number of children differs " + left + " " + r return false; } for (int i = 0; i < leftChildren.size(); ++i) { if(!internalIsSameStructure(leftChildren.get(i), rightChildren.get errorMessage.append("Children differ " + left + " " + right + return false; } } Text return true; } protected boolean isSameClass(EClass left, EClass right) { return left.getName().equals(right.getName()) && left.getEPackage().getNsURI().equals(right.getEPackage().g } protected List<EObject> getRelevantChildren(EObject _this) { List<EObject> relevantChildren = new ArrayList<EObject>(_this.eContents( for (Iterator<EObject> i = relevantChildren.iterator(); i.hasNext();) { EObject next = i.next(); if (!isRelevantChild(_this, next)) { i.remove(); } } return relevantChildren; } protected boolean isRelevantChild(EObject container, EObject child) { return true;

} protected String getErrorMessage() { return errorMessage.toString(); } Graphics public boolean isSameStructure(EObject left, EObject right) { counter = 0; return internalIsSameStructure(left, right); } • High-level views public boolean internalIsSameStructure(EObject left, EObject right) { ++counter; if (!isSameClass(left.eClass(), right.eClass())) { errorMessage.append("Classes are not equal: " + left + " != " + ri return false; } List<EObject> leftChildren = getRelevantChildren(left); List<EObject> rightChildren = getRelevantChildren(right); if(leftChildren.size() != rightChildren.size()) { errorMessage.append("Number of children differs " + left + " " + r return false; } for (int i = 0; i < leftChildren.size(); ++i) { if(!internalIsSameStructure(leftChildren.get(i), rightChildren.get errorMessage.append("Children differ " + left + " " + right + return false; } } Text return true; } protected boolean isSameClass(EClass left, EClass right) { return left.getName().equals(right.getName()) && left.getEPackage().getNsURI().equals(right.getEPackage().g } protected List<EObject> getRelevantChildren(EObject _this) { List<EObject> relevantChildren = new ArrayList<EObject>(_this.eContents( for (Iterator<EObject> i = relevantChildren.iterator(); i.hasNext();) { EObject next = i.next(); if (!isRelevantChild(_this, next)) { i.remove(); } } return relevantChildren; } protected boolean isRelevantChild(EObject container, EObject child) { return true;

} protected String getErrorMessage() { return errorMessage.toString(); } Graphics public boolean isSameStructure(EObject left, EObject right) { counter = 0; return internalIsSameStructure(left, right); } • High-level views public boolean internalIsSameStructure(EObject left, EObject right) { ++counter; if (!isSameClass(left.eClass(), right.eClass())) { errorMessage.append("Classes are not equal: " + left + " != " + ri return false; } List<EObject> leftChildren = getRelevantChildren(left); List<EObject> rightChildren = getRelevantChildren(right); if(leftChildren.size() != rightChildren.size()) { errorMessage.append("Number of children differs " + left + " " + r return false; } for (int i = 0; i < leftChildren.size(); ++i) { if(!internalIsSameStructure(leftChildren.get(i), rightChildren.get errorMessage.append("Children differ " + left + " " + right + return false; } } Text return true; } protected boolean isSameClass(EClass left, EClass right) { return left.getName().equals(right.getName()) } • Detailed views && left.getEPackage().getNsURI().equals(right.getEPackage().g protected List<EObject> getRelevantChildren(EObject _this) { List<EObject> relevantChildren = new ArrayList<EObject>(_this.eContents( for (Iterator<EObject> i = relevantChildren.iterator(); i.hasNext();) { EObject next = i.next(); if (!isRelevantChild(_this, next)) { i.remove(); } } return relevantChildren; } protected boolean isRelevantChild(EObject container, EObject child) { return true;

} protected String getErrorMessage() { return errorMessage.toString(); } Graphics public boolean isSameStructure(EObject left, EObject right) { counter = 0; return internalIsSameStructure(left, right); } • High-level views public boolean internalIsSameStructure(EObject left, EObject right) { • ++counter; Suggests non-formalism if (!isSameClass(left.eClass(), right.eClass())) { errorMessage.append("Classes are not equal: " + left + " != " + ri return false; } List<EObject> leftChildren = getRelevantChildren(left); List<EObject> rightChildren = getRelevantChildren(right); if(leftChildren.size() != rightChildren.size()) { errorMessage.append("Number of children differs " + left + " " + r return false; } for (int i = 0; i < leftChildren.size(); ++i) { if(!internalIsSameStructure(leftChildren.get(i), rightChildren.get errorMessage.append("Children differ " + left + " " + right + return false; } } Text return true; } protected boolean isSameClass(EClass left, EClass right) { return left.getName().equals(right.getName()) } • Detailed views && left.getEPackage().getNsURI().equals(right.getEPackage().g protected List<EObject> getRelevantChildren(EObject _this) { List<EObject> relevantChildren = new ArrayList<EObject>(_this.eContents( for (Iterator<EObject> i = relevantChildren.iterator(); i.hasNext();) { EObject next = i.next(); if (!isRelevantChild(_this, next)) { i.remove(); } } return relevantChildren; } protected boolean isRelevantChild(EObject container, EObject child) { return true;

} protected String getErrorMessage() { return errorMessage.toString(); } Graphics public boolean isSameStructure(EObject left, EObject right) { counter = 0; return internalIsSameStructure(left, right); } • High-level views public boolean internalIsSameStructure(EObject left, EObject right) { • ++counter; Suggests non-formalism if (!isSameClass(left.eClass(), right.eClass())) { errorMessage.append("Classes are not equal: " + left + " != " + ri return false; } List<EObject> leftChildren = getRelevantChildren(left); List<EObject> rightChildren = getRelevantChildren(right); if(leftChildren.size() != rightChildren.size()) { errorMessage.append("Number of children differs " + left + " " + r return false; } for (int i = 0; i < leftChildren.size(); ++i) { if(!internalIsSameStructure(leftChildren.get(i), rightChildren.get errorMessage.append("Children differ " + left + " " + right + return false; } } Text return true; } protected boolean isSameClass(EClass left, EClass right) { return left.getName().equals(right.getName()) } • Detailed views && left.getEPackage().getNsURI().equals(right.getEPackage().g • Formal protected List<EObject> getRelevantChildren(EObject _this) { List<EObject> relevantChildren = new ArrayList<EObject>(_this.eContents( for (Iterator<EObject> i = relevantChildren.iterator(); i.hasNext();) { EObject next = i.next(); if (!isRelevantChild(_this, next)) { i.remove(); } } return relevantChildren; } protected boolean isRelevantChild(EObject container, EObject child) { return true;

} protected String getErrorMessage() { return errorMessage.toString(); } Graphics public boolean isSameStructure(EObject left, EObject right) { counter = 0; return internalIsSameStructure(left, right); } • High-level views public boolean internalIsSameStructure(EObject left, EObject right) { • ++counter; Suggests non-formalism if (!isSameClass(left.eClass(), right.eClass())) { errorMessage.append("Classes are not equal: " + left + " != " + ri • Individual tools return false; } List<EObject> leftChildren = getRelevantChildren(left); List<EObject> rightChildren = getRelevantChildren(right); if(leftChildren.size() != rightChildren.size()) { errorMessage.append("Number of children differs " + left + " " + r return false; } for (int i = 0; i < leftChildren.size(); ++i) { if(!internalIsSameStructure(leftChildren.get(i), rightChildren.get errorMessage.append("Children differ " + left + " " + right + return false; } } Text return true; } protected boolean isSameClass(EClass left, EClass right) { return left.getName().equals(right.getName()) } • Detailed views && left.getEPackage().getNsURI().equals(right.getEPackage().g • Formal protected List<EObject> getRelevantChildren(EObject _this) { List<EObject> relevantChildren = new ArrayList<EObject>(_this.eContents( for (Iterator<EObject> i = relevantChildren.iterator(); i.hasNext();) { EObject next = i.next(); if (!isRelevantChild(_this, next)) { i.remove(); } } return relevantChildren; } protected boolean isRelevantChild(EObject container, EObject child) { return true;

} protected String getErrorMessage() { return errorMessage.toString(); } Graphics public boolean isSameStructure(EObject left, EObject right) { counter = 0; return internalIsSameStructure(left, right); } • High-level views public boolean internalIsSameStructure(EObject left, EObject right) { • ++counter; Suggests non-formalism if (!isSameClass(left.eClass(), right.eClass())) { errorMessage.append("Classes are not equal: " + left + " != " + ri • Individual tools return false; } List<EObject> leftChildren = getRelevantChildren(left); List<EObject> rightChildren = getRelevantChildren(right); if(leftChildren.size() != rightChildren.size()) { errorMessage.append("Number of children differs " + left + " " + r return false; } for (int i = 0; i < leftChildren.size(); ++i) { if(!internalIsSameStructure(leftChildren.get(i), rightChildren.get errorMessage.append("Children differ " + left + " " + right + return false; } } Text return true; } protected boolean isSameClass(EClass left, EClass right) { return left.getName().equals(right.getName()) } • Detailed views && left.getEPackage().getNsURI().equals(right.getEPackage().g • Formal protected List<EObject> getRelevantChildren(EObject _this) { List<EObject> relevantChildren = new ArrayList<EObject>(_this.eContents( • Well established tools for (Iterator<EObject> i = relevantChildren.iterator(); i.hasNext();) { EObject next = i.next(); if (!isRelevantChild(_this, next)) { i.remove(); } } return relevantChildren; } protected boolean isRelevantChild(EObject container, EObject child) { return true;

} protected String getErrorMessage() { return errorMessage.toString(); } Graphics public boolean isSameStructure(EObject left, EObject right) { counter = 0; return internalIsSameStructure(left, right); } • High-level views public boolean internalIsSameStructure(EObject left, EObject right) { • ++counter; Suggests non-formalism if (!isSameClass(left.eClass(), right.eClass())) { errorMessage.append("Classes are not equal: " + left + " != " + ri • Individual tools return false; } List<EObject> leftChildren = getRelevantChildren(left); • Hard to evolve List<EObject> rightChildren = getRelevantChildren(right); if(leftChildren.size() != rightChildren.size()) { errorMessage.append("Number of children differs " + left + " " + r return false; } for (int i = 0; i < leftChildren.size(); ++i) { if(!internalIsSameStructure(leftChildren.get(i), rightChildren.get errorMessage.append("Children differ " + left + " " + right + return false; } } Text return true; } protected boolean isSameClass(EClass left, EClass right) { return left.getName().equals(right.getName()) } • Detailed views && left.getEPackage().getNsURI().equals(right.getEPackage().g • Formal protected List<EObject> getRelevantChildren(EObject _this) { List<EObject> relevantChildren = new ArrayList<EObject>(_this.eContents( • Well established tools for (Iterator<EObject> i = relevantChildren.iterator(); i.hasNext();) { EObject next = i.next(); if (!isRelevantChild(_this, next)) { i.remove(); } } return relevantChildren; } protected boolean isRelevantChild(EObject container, EObject child) { return true;

} protected String getErrorMessage() { return errorMessage.toString(); } Graphics public boolean isSameStructure(EObject left, EObject right) { counter = 0; return internalIsSameStructure(left, right); } • High-level views public boolean internalIsSameStructure(EObject left, EObject right) { • ++counter; Suggests non-formalism if (!isSameClass(left.eClass(), right.eClass())) { errorMessage.append("Classes are not equal: " + left + " != " + ri • Individual tools return false; } List<EObject> leftChildren = getRelevantChildren(left); • Hard to evolve List<EObject> rightChildren = getRelevantChildren(right); if(leftChildren.size() != rightChildren.size()) { errorMessage.append("Number of children differs " + left + " " + r return false; } for (int i = 0; i < leftChildren.size(); ++i) { if(!internalIsSameStructure(leftChildren.get(i), rightChildren.get errorMessage.append("Children differ " + left + " " + right + return false; } } Text return true; } protected boolean isSameClass(EClass left, EClass right) { return left.getName().equals(right.getName()) } • Detailed views && left.getEPackage().getNsURI().equals(right.getEPackage().g • Formal protected List<EObject> getRelevantChildren(EObject _this) { List<EObject> relevantChildren = new ArrayList<EObject>(_this.eContents( • Well established tools for (Iterator<EObject> i = relevantChildren.iterator(); i.hasNext();) { EObject next = i.next(); if (!isRelevantChild(_this, next)) { } } • Easy to evolve i.remove(); return relevantChildren; } protected boolean isRelevantChild(EObject container, EObject child) { return true;

} protected String getErrorMessage() { return errorMessage.toString(); } Graphics public boolean isSameStructure(EObject left, EObject right) { counter = 0; return internalIsSameStructure(left, right); } • High-level views public boolean internalIsSameStructure(EObject left, EObject right) { • ++counter; Suggests non-formalism if (!isSameClass(left.eClass(), right.eClass())) { errorMessage.append("Classes are not equal: " + left + " != " + ri • Individual tools return false; } List<EObject> leftChildren = getRelevantChildren(left); • Hard to evolve List<EObject> rightChildren = getRelevantChildren(right); if(leftChildren.size() != rightChildren.size()) { errorMessage.append("Number of children differs " + left + " " + r • Editing with mouse } return false; for (int i = 0; i < leftChildren.size(); ++i) { if(!internalIsSameStructure(leftChildren.get(i), rightChildren.get errorMessage.append("Children differ " + left + " " + right + return false; } } Text return true; } protected boolean isSameClass(EClass left, EClass right) { return left.getName().equals(right.getName()) } • Detailed views && left.getEPackage().getNsURI().equals(right.getEPackage().g • Formal protected List<EObject> getRelevantChildren(EObject _this) { List<EObject> relevantChildren = new ArrayList<EObject>(_this.eContents( • Well established tools for (Iterator<EObject> i = relevantChildren.iterator(); i.hasNext();) { EObject next = i.next(); if (!isRelevantChild(_this, next)) { } } • Easy to evolve i.remove(); return relevantChildren; } protected boolean isRelevantChild(EObject container, EObject child) { return true;

} protected String getErrorMessage() { return errorMessage.toString(); } Graphics public boolean isSameStructure(EObject left, EObject right) { counter = 0; return internalIsSameStructure(left, right); } • High-level views public boolean internalIsSameStructure(EObject left, EObject right) { • ++counter; Suggests non-formalism if (!isSameClass(left.eClass(), right.eClass())) { errorMessage.append("Classes are not equal: " + left + " != " + ri • Individual tools return false; } List<EObject> leftChildren = getRelevantChildren(left); • Hard to evolve List<EObject> rightChildren = getRelevantChildren(right); if(leftChildren.size() != rightChildren.size()) { errorMessage.append("Number of children differs " + left + " " + r • Editing with mouse } return false; for (int i = 0; i < leftChildren.size(); ++i) { if(!internalIsSameStructure(leftChildren.get(i), rightChildren.get errorMessage.append("Children differ " + left + " " + right + return false; } } Text return true; } protected boolean isSameClass(EClass left, EClass right) { return left.getName().equals(right.getName()) } • Detailed views && left.getEPackage().getNsURI().equals(right.getEPackage().g • Formal protected List<EObject> getRelevantChildren(EObject _this) { List<EObject> relevantChildren = new ArrayList<EObject>(_this.eContents( • Well established tools for (Iterator<EObject> i = relevantChildren.iterator(); i.hasNext();) { EObject next = i.next(); if (!isRelevantChild(_this, next)) { } • Easy to evolve i.remove(); • } } Editing with keyboard return relevantChildren; protected boolean isRelevantChild(EObject container, EObject child) { return true;

Showtime ! • In your Eclipse workbench • Choose Run->Run conﬁgurations... • Double click on Eclipse Application • Go to the Arguments tab and add -XX:MaxPermSize=128m to the VM arguments • Click on Run

A Guided Example entity Conference { property Name : String on Attendees refs many Pers Sp eakers refs many Speaker } entity Person { property Name : String } { enti ty Speaker extends Person n Sessions refs many Sessio } entity Session { property Title: String property IsTutorial : Bool }

Grammar Language grammar org.xtext.cg2009.Entities with org.eclipse.xtext.common.Terminals generate entities "http://www.xtext.org/cg2009/Entities" Model : (entities += Entity)+; Entity returns Entity: 'entity' name=ID ('extends' superType=[Entity])? '{' (properties+=Property)* '}'; Property: SimpleProperty | ReferenceProperty; SimpleProperty: 'property' name=ID ':' type=('String'|'Number'|'Bool'); ReferenceProperty : name=ID 'refs' ('one' | many?='many')? type=[Entity];

Edit SQL with Xtext CREATE TABLE Conferences ( id INTEGER NOT NULL PRIMARY KEY, • Only ) name CHAR(50) Create-Statements • List of columns

Edit SQL with Xtext CREATE TABLE Conferences ( id INTEGER NOT NULL PRIMARY KEY, name CHAR(50) • Enhance with ) Foreign Keys CREATE TABLE Speaker ( name CHAR(50), id INTEGER, FOREIGN KEY (id) REFERENCES Conference(id) )

What’s wrong with it?

Cross References

Cross References Model Element

Cross References Element Name Model Element

Cross References Element Name resolve Model Element

Cross References Element Name resolve determin Model Element

Problem: Names may not be ambiguous.

Problem: Names may not be ambiguous. Solution: Implement a ScopeProvider!

Problem: Names may not be ambiguous. Solution: Implement a ScopeProvider! A Scope is a context speciﬁc, hierarchical collection of all reachable model elements and their respective names.

Scope Provider Make Foreign Keys work! public IScope scope_ForeignKey_from( ForeignKey context, EReference reference) { Table fromTable = (Table) context.eContainer(); return createTableScope(fromTable); }

Meta-Model Inference grammar org.xtext.codeGeneration.Entities with org.eclipse.xtext.common.Terminals generate entities "http://www.xtext.org/CG2009/Entities" Model : (entities += Entity)+; Entity returns Entity: 'entity' name=ID ('extends' superType=[Entity])? '{' (properties+=Property)* '}'; Property: SimpleProperty | ReferenceProperty; SimpleProperty: 'property' name=ID ':' type=('String'|'Number'|'Bool'); ReferenceProperty : name=ID 'refs' ('one' | many?='many')? type=[Entity];

Model Conferences with Xtext How do I create a language for an existing meta-model?

Model Conferences with Xtext

Validate Your Conference 1. Have a look at the generated Validator-Stub. 2. Implement some checks for your language. 3. Check out the results. @Check public void checkSpeakersName(Speaker speaker) { assertTrue("Speaker's name is to short.", ConferencesLanguagePackage.SPEAKER__NAME, speaker.getName().length() >= 2); }

Convention over Conﬁguration

Conﬁgured with Google Guice class MyDslRuntimeModule extends DefaultRuntimeModule { Class<? extends ServiceInterface> bindService() { return MyServiceImplementation.class; } }

Extensible Language Generator • Generates a lot of Java code • Composed of fragments • Customizable • Add your own fragments!

http://www.wordle.net/

Formatting Pretty Printing Code Beautiﬁcation import <Literature.entities> entity City {Int id; String name;} entity Store { Int id; String name; Int city references City. id; }

Formatting Pretty Printing Code Beautiﬁcation import <Literature.entities> entity City {Int id; String name;} entity Store { Int id; String name; Int import <Literature.entities> city references entity City { City. Int id; id; } String name; } entity Store { Int id; String name; Int city references City.id; }

Formatting Pretty Printing Code Beautiﬁcation import <Literature.entities> entity City {Int id; String name;} entity Store { Int id; String name; Int import <Literature.entities> city references entity City { City. Int id; id; } String name; } entity Store { Int id; String name; Int city references City.id; § 1. At ... do ... } § 2. At ... do ... § 3. At ... do ... § 4. At ... do ... ...

Integration with EMF

Integration with EMF eclipse Any EMF-based modeling Code Generator GMF Editor P R O J E C T Component

Integration with EMF eclipse Any EMF-based modeling Code Generator GMF Editor P R O J E C T Component <<abstract>> XMIResource Resource

Integration with EMF eclipse Any EMF-based modeling Code Generator GMF Editor P R O J E C T Component <<abstract>> XMI XMIResource Resource

Integration with EMF eclipse Any EMF-based modeling Code Generator GMF Editor P R O J E C T Component <<abstract>> XMI XMIResource Resource XtextResource

Integration with EMF eclipse Any EMF-based modeling Code Generator GMF Editor P R O J E C T Component <<abstract>> XMI XMIResource Resource XtextResource Text

Integration with EMF eclipse Any EMF-based modeling Code Generator GMF Editor P R O J E C T Component <<abstract>> XMI XMIResource Resource XtextResource Text Parser Linker Serializer ValueConverter ScopeProvider Formatter

EMF Index • Indexes all resources in workspace • Query elements and cross-references • Efﬁcient scoping

EMF Index • Indexes all resources in workspace • Query elements and cross-references • Efﬁcient scoping Load Resources

Learn more at http://www.xtext.org

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Workshop On Xtext

by Jan Koehnlein on Jun 19, 2009

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