Xtext makes it easy to define domain specific languages, but making your DSL a first class programming artifact with support for expressions and integration with Java is a hard thing if you do it from scratch. The Xbase library is an integral part of the Xtext framework. Xbase implements the bridge from DSLs to Java. It greatly simplifies your language implementation, if you want to run your DSL on the JVM. Xbase consists of a very powerful Java-like expression grammar and implements all the necessary infrastructure to link your DSL against existing Java types, compile it to executable code and validate it against the JVM specific constraints. In this session I want to explain how Xbase works under the covers and dive into its APIs. You will see, how to enhance your language and make it highly expressive and powerful without introducing an artificial gap to the Java platform. If you want your DSL to be a first class programming artifact, come to this session and see how to benefit best from Xbase.

1. Introduction to Xbase
Holger Schill

2. What is

3. public class Customer implements Serializable {
private String name;
private Address address;
private List<Phone> phones;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Address getAddress() {
return address;
}
public void setAddress(Address address) {
this.address = address;
}
public List<Phone> getPhones() {
return phones;
}
public void setPhones(List<Phone> phones) {
this.phones = phones;
}
}
bean Customer {
name: String
address: Address
phones: Phone*
}

4. @Entity
public class Customer implements Serializable {
@Id
private String name;
private Address address;
private List<Phone> phones;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
@Column(name="ADDR", nullable=false)
public Address getAddress() {
return address;
}
public void setAddress(Address address) {
this.address = address;
}
@OneToMany
public List<Phone> getPhones() {
return phones;
}
public void setPhones(List<Phone> phones) {
this.phones = phones;
}
}
bean Customer {
name: String
address: Address
phones: Phone*
}

5. Grammar
grammar org.xtext.example.BeanDsl with org.eclipse.xtext.xbase.Xbase
generate beanDsl "http://www.xtext.org/example/BeanDsl"
Root:
beans+=Bean*;
Bean:
'bean' name=ID '{'
property+=Property*
'}'
;
Property:
name=ID ':' (simpleType=TYPE | reference=[Bean]) list?='*'?
;
enum TYPE:
String | Int
;

6. Editor and much more…

7. Wouldn’t it be cool when…

8. Expressions would be
directly in the DSL…

9. …with a typesystem

10. and debugging support

11. Typesystem
Compiler / Interpreter
Complex Syntax
Expressions
Debugging

12. Xbase
Reusable expression language
Access to Java-elements
Typesystem
Compiled to Java
Interpreter
…

13. Core Principles
Common (JVM) Type Model
DSLs with Expressions
Scoping Validation ... Generator
Java

14. DSL
.class
FileAST
Type Model
.java
File
(references)
Core Principles

15. DSL
.class
FileAST
.java
File
(references)
Core Principles

16. .class
File
Derived Java
Types
.java
File
DSL
AST
Core Principles

17. DSL
.class
File
.java
File
AST
Derived Java
Types
Core Principles

18. DSL
.java
File
.class
File
.java
File
Core Principles

19. DEMO

20. What about new
Expressions

21. Create a new ParserRule
Weave it into the Expression Tree
Convince Antlr
Compute the type for it
Implement a compiler
Ingredients

22. Create a new ParserRule
Weave it into the Expression Tree
Convince Antlr
Compute the type for it
Implement a compiler
Ingredients
Justkidding:-)

23. Extending the Xbase Type System
Sebastian Zarnekow
Today
13:00 - 13:50

24. THANKS