1.
Building DSLs with
Eclipse
Peter Friese, itemis
@peterfriese
@xtext
(c) 2009 Peter Friese. Distributed under the EDL V1.0 - http://www.eclipse.org/org/documents/edl-v10.php
More info: http://www.peterfriese.de / http://www.itemis.com

2.
What is a DSL?

3.
Domain

4.
Language

5.
Suppose...

6.
You’d want to core an apple...

7.
... for your kids.

8.
?
Right tool for the job?

9.
Your trusty swiss army knife!

10.
Because you can use it for other stuff, too.
E.g., opening a bottle of wine.

11.
Suppose...

12.
You’d want to core a few more apples...

13.
... for an apple cake.

14.
Still the best tool for the job?

15.
Better use this one.

16.
and this one:

17.
BUT
avoid the unitasker!

18.
BUT
avoid the unitasker!

19.
... a DSL is ...

20.
A specific tool
for a specific job

21.
A specific tool
for a specific job

22.
Samples for DSLs

23.
SQL

24.
select name, salary
from employees
where salary > 2000
order by salary

25.
ANT

26.
<project name="MyProject" default="dist" basedir=".">
<property name="src" location="src"/>
<property name="build" location="build"/>
<property name="dist" location="dist"/>
<target name="init">
<mkdir dir="${build}"/>
</target>
<target name="compile" depends="init">
<javac srcdir="${src}" destdir="${build}"/>
</target>
<target name="dist" depends="compile">
<mkdir dir="${dist}/lib"/>
<jar jarfile="${dist}/lib/MyProject.jar"
basedir="${build}"/>
</target>
<target name="clean">
<delete dir="${build}"/>
<delete dir="${dist}"/>
</target>
</project>

27.
<project name="MyProject" default="dist" basedir=".">
<property name="src" location="src"/>
<property name="build" location="build"/>
<property name="dist" location="dist"/>
<target name="init">
<mkdir dir="${build}"/>
</target>
<target name="compile" depends="init">
<javac srcdir="${src}" destdir="${build}"/>
</target>
<target name="dist" depends="compile">
<mkdir dir="${dist}/lib"/>
<jar jarfile="${dist}/lib/MyProject.jar"
basedir="${build}"/>
</target>
<target name="clean">
<delete dir="${build}"/>
<delete dir="${dist}"/>
</target>
</project>

28.
External
or
Internal

29.
Internal DSLs

30.
Mailer.mail()
.to(“you@gmail.com”)
.from(“me@gmail.com”)
.subject(“Writing DSLs in Java”)
.body(“...”)
.send();

31.
Simple

32.
Limited

33.
External DSLs

34.
1)Create ANTLR grammar
2)Generate lexer / parser
3)Parser will create parse tree
4)Transform parse tree to semantic model
5)Iterate model
6)Pass model element(s) to template

35.
Flexible

36.
Adaptable

37.
Complicated

38.
Why not use a DSL...
... for building DSLs?

39.
Demo 1

40.
@SuppressWarnings("serial")
@Entity
@Table(name = "CUSTOMER_INFO")
public class CustomerInfo implements Serializable {
@Id
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "idSeq")
@SequenceGenerator(name = "idSeq", sequenceName = "CUST_SEQ", allocationSize = 1)
@Column(name = "CUST_ID", nullable = false)
private String customerId;
public void setCustomerId(String customerId) {
this.customerId = customerId;
}
public String getCustomerId() {
return customerId;
}
@Column(name = "EMAIL", nullable = false, length = 128)
private String emailAddress;
public String getEmailAddress() {
return emailAddress;
}
public void setEmailAddress(String emailAddress) {
String oldValue = emailAddress;
this.emailAddress = emailAddress;
firePropertyChangedEvent("emailAddress", oldValue, this.emailAddress);
}

41.
@SuppressWarnings("serial")
@Entity
@Table(name = "CUSTOMER_INFO")
public class CustomerInfo implements Serializable {
@Id
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "idSeq")
@SequenceGenerator(name = "idSeq", sequenceName = "CUST_SEQ", allocationSize = 1)
@Column(name = "CUST_ID", nullable = false)
private String customerId;
public void setCustomerId(String customerId) {
this.customerId = customerId;
}
public String getCustomerId() {
return customerId;
}
@Column(name = "EMAIL", nullable = false, length = 128)
private String emailAddress;
public String getEmailAddress() {
return emailAddress;
}
public void setEmailAddress(String emailAddress) {
String oldValue = emailAddress;
this.emailAddress = emailAddress;
firePropertyChangedEvent("emailAddress", oldValue, this.emailAddress);
}

42.
entity CustomerInfo
(id=CUST_ID, sequenceName=CUST_SEQ)
{
String emailAddress (notNull, length = 128)
}

43.
entity CustomerInfo
(id=CUST_ID, sequenceName=CUST_SEQ)
{
String emailAddress (notNull, length = 128)
}
Bean
DAO
(POJO)

44.
Underlying Technology

45.
Model
G
ra
m
m
ar

46.
ar
Model
m
m
ra
G
Generator

47.
ar
Model
m
m
ra
G
Generator
Runtime
Superclass
Subclass Class
LL(*) Parser ECore meta model Editor

48.
ar
Model
m
m
ra
G
Generator
Runtime
Superclass
Subclass Class
LL(*) Parser ECore meta model Editor

49.
Grammar (similar to EBNF)
grammar org.xtext.example.Entity with org.eclipse.xtext.common.Terminals
generate entity "http://www.xtext.org/example/Entity"
Model:
(types+=Type)*;
Type:
TypeDef | Entity;
TypeDef:
"typedef" name=ID ("mapsto" mappedType=JAVAID)?;
JAVAID:
name=ID("." ID)*;
Entity:
"entity" name=ID ("extends" superEntity=[Entity])?
"{"
(attributes+=Attribute)*
"}";
Attribute:
type=[Type] (many?="*")? name=ID;

50.
grammar org.xtext.example.Entity
with org.eclipse.xtext.common.Terminals Meta model inference
generate entity
"http://www.xtext.org/example/Entity"
entity
Model:
(types+=Type)*;
Model
Type:
TypeDef | Entity;
types
TypeDef: *
Type
"typedef" name=ID
name: EString
("mapsto" mappedType=JAVAID)?;
superEntity
JAVAID:
name=ID("." ID)*; TypeDef Entity
Entity: mappedType attributes
"entity" name=ID
Attribute
("extends" superEntity=[Entity])? JAVAID
name: EString
"{" name: EString
many: EBoolean
(attributes+=Attribute)*
"}"; type
Attribute:
type=[Type] (many?="*")? name=ID;

51.
grammar org.xtext.example.Entity
with org.eclipse.xtext.common.Terminals Meta model inference
generate entity
"http://www.xtext.org/example/Entity"
entity Rules -> Classes
Model:
(types+=Type)*;
Model
Type:
TypeDef | Entity;
types
TypeDef: *
Type
"typedef" name=ID
name: EString
("mapsto" mappedType=JAVAID)?;
superEntity
JAVAID:
name=ID("." ID)*; TypeDef Entity
Entity: mappedType attributes
"entity" name=ID
Attribute
("extends" superEntity=[Entity])? JAVAID
name: EString
"{" name: EString
many: EBoolean
(attributes+=Attribute)*
"}"; type
Attribute:
type=[Type] (many?="*")? name=ID;

52.
grammar org.xtext.example.Entity
with org.eclipse.xtext.common.Terminals Meta model inference
generate entity
"http://www.xtext.org/example/Entity"
entity
Model:
(types+=Type)*;
Model
Type:
TypeDef | Entity;
types
TypeDef: *
Type
"typedef" name=ID
name: EString
("mapsto" mappedType=JAVAID)?;
superEntity
JAVAID:
name=ID("." ID)*; TypeDef Entity
Entity: mappedType attributes
"entity" name=ID
Attribute
("extends" superEntity=[Entity])? JAVAID
name: EString
"{" name: EString
many: EBoolean
(attributes+=Attribute)*
"}"; type
Attribute:
type=[Type] (many?="*")? name=ID;

53.
grammar org.xtext.example.Entity
with org.eclipse.xtext.common.Terminals Meta model inference
generate entity
"http://www.xtext.org/example/Entity"
entity Alternatives -> Hierarchy
Model:
(types+=Type)*;
Model
Type:
TypeDef | Entity;
types
TypeDef: *
Type
"typedef" name=ID
name: EString
("mapsto" mappedType=JAVAID)?;
superEntity
JAVAID:
name=ID("." ID)*; TypeDef Entity
Entity: mappedType attributes
"entity" name=ID
Attribute
("extends" superEntity=[Entity])? JAVAID
name: EString
"{" name: EString
many: EBoolean
(attributes+=Attribute)*
"}"; type
Attribute:
type=[Type] (many?="*")? name=ID;

54.
grammar org.xtext.example.Entity
with org.eclipse.xtext.common.Terminals Meta model inference
generate entity
"http://www.xtext.org/example/Entity"
entity
Model:
(types+=Type)*;
Model
Type:
TypeDef | Entity;
types
TypeDef: *
Type
"typedef" name=ID
name: EString
("mapsto" mappedType=JAVAID)?;
superEntity
JAVAID:
name=ID("." ID)*; TypeDef Entity
Entity: mappedType attributes
"entity" name=ID
Attribute
("extends" superEntity=[Entity])? JAVAID
name: EString
"{" name: EString
many: EBoolean
(attributes+=Attribute)*
"}"; type
Attribute:
type=[Type] (many?="*")? name=ID;

55.
grammar org.xtext.example.Entity
with org.eclipse.xtext.common.Terminals Meta model inference
generate entity
"http://www.xtext.org/example/Entity"
entity Assignment -> Feature
Model:
(types+=Type)*;
Model
Type:
TypeDef | Entity;
types
TypeDef: *
Type
"typedef" name=ID
name: EString
("mapsto" mappedType=JAVAID)?;
superEntity
JAVAID:
name=ID("." ID)*; TypeDef Entity
Entity: mappedType attributes
"entity" name=ID
Attribute
("extends" superEntity=[Entity])? JAVAID
name: EString
"{" name: EString
many: EBoolean
(attributes+=Attribute)*
"}"; type
Attribute:
type=[Type] (many?="*")? name=ID;

56.
grammar org.xtext.example.Entity
with org.eclipse.xtext.common.Terminals Meta model inference
generate entity
"http://www.xtext.org/example/Entity"
entity
Model:
(types+=Type)*;
Model
Type:
TypeDef | Entity;
types
TypeDef: *
Type
"typedef" name=ID
name: EString
("mapsto" mappedType=JAVAID)?;
superEntity
JAVAID:
name=ID("." ID)*; TypeDef Entity
Entity: mappedType attributes
"entity" name=ID
Attribute
("extends" superEntity=[Entity])? JAVAID
name: EString
"{" name: EString
many: EBoolean
(attributes+=Attribute)*
"}"; type
Attribute:
type=[Type] (many?="*")? name=ID;

57.
Demo 2

58.
Poll "Simple poll"
question "What's your name?" name
question "How do you feel today?" howareyou
() "Fine" fine
() "Great" great
() "Bad" bad
() "Not too bad" not2bad
question "What's your favourite food?" food
[] "Pizza" pizza
[] "Pasta" pasta
[] "Sushi" sushi
[] "Mexican" mexican

59.
Pimp My Write

60.
Tooltips
Scoping
Outline
Label Provider
Validation Hyperlinking / Navigation
AST
Code Formatting
Content Assist
Folding
Quick Fix
Datatype Converter
Parser
Syntax Highlighting

61.
Tooltips
Scoping
Outline
Hyperlinking / Navigation
AST
Code Formatting
Content Assist
Folding
Quick Fix
Datatype Converter
Parser
Syntax Highlighting

62.
Tooltips
Scoping
Outline
Label Provider
Validation Hyperlinking / Navigation
AST
Code Formatting
Content Assist
Folding
Quick Fix
Datatype Converter
Parser
Syntax Highlighting

63.
Conclusion

64.
Abstraction

65.
Use a DSL to develop your tools

66.
Support
Newsgroup
Community Forum
Professional Support

67.
Heiko Sven Moritz Peter Dennis Jan Patrick Sebastian Michael Knut
Behrens Efftinge Eysholdt Friese Hübner Köhnlein Schönbach Zarnekow Clay Wannheden
Individual

68.
Twitter: @xtext
http://www.xtext.org