This document discusses using Xtext to create domain-specific languages (DSLs) for Java. It describes how Xtext allows defining a DSL grammar and then generates Java code from that DSL. This includes inferring models from the DSL that map to Java classes and methods. Xtext also supports integrating DSLs with Java typesystems and other Java elements.

1. Java DSLs
with Xtext
Jan Koehnlein
Mittwoch, 27. März 13

2. Mittwoch, 27. März 13

3. Mittwoch, 27. März 13

4. public class Customer implements Serializable {
private String name;
private Address address;
private List<Item> purchase;
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<Item> getPurchase() {
return purchase;
}
public void setPurchase(List<Item> items) {
this.purchase = purchase;
}
}
Mittwoch, 27. März 13

5. @Entity
public class Customer implements Serializable {
@Id
private String name;
private Address address;
private List<Item> purchase;
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;
}
@ManyToMany
public List<Item> getPurchase() {
return purchase;
}
public void setPurchase(List<Item> items) {
this.purchase = purchase;
}
}
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6. Domain-Specific Languages
Mittwoch, 27. März 13

7. DSL Java
entity Customer {
@Entity
name: String public class Customer implements Serializable {
@Id
address: Address private String name;
purchase: Item*
private Address address;
private List<Item> purchase;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
@Column(name="ADDR", nullable=false)
Code
public Address getAddress() {
}
return address;
public void setAddress(Address address) {
Generation
this.address = address;
}
@ManyToMany
public List<Item> getPurchase() {
return purchase;
}
public void setPurchase(List<Item> items) {
this.purchase = purchase;
}
}
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8. ?
Methods
Logic
Arithmetics
Behavior
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9. entity Customer {
name: String
address: Address
purchase: Item*
double sales() {
double result = 0.0;
for(Item item: purchase)
result += item.getPrice();
return result;
}
}
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10. Expressions
Complex Syntax
Typesystem
Compiler / Interpreter
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11. Integration Patterns
Manually
written
code
Generated
code
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12. Reusable powerful expression
library language
Java‘s Typesystem
Access to Java-elements
Compile to Java Code
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13. DSLs
for
Java
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14. grammar inheritance
Grammar (Parser, Lexer)
Linker
Type System
JvmModel
MyLanguage Interpreter /
Advanced Editor
Eclipse Integration
Debugger
JvmModelInferrer
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15. Model Inference
Class Customer
entity Customer {
name: String Field name
address: Address
purchasedItems: Item* Method getName
double sales() {
purchasedItems
returnType String
.map[price]
.reduce[a,b|a+b]
} Method setName
}
parameter name
type String
Mittwoch, 27. März 13

16. Model Inference
entity Customer {
name: String
address: Address
purchasedItems: Item*
double sales() { Method sales
purchasedItems
.map[price] returnType double
.reduce[a,b|a+b]
}
body Expression
}
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17. class ScriptingJvmModelInferrer extends AbstractModelInferrer {
@Inject extension JvmTypesBuilder
def dispatch void infer(Script script,
IJvmDeclaredTypeAcceptor acceptor,
boolean isPreIndexingPhase) {
acceptor.accept(script.toClass('MyClass'))
.initializeLater [
// the class gets one main method
members += script.toMethod(
'main',
script.newTypeRef(Void::TYPE)) [
parameters += script.toParameter("args",
script.newTypeRef(typeof(String))
.addArrayTypeDimension)
static = true
varArgs = true
// Associate the script as the body of the main method
body = script
]
]
}
}
Mittwoch, 27. März 13

18. The 7 Languages
Scripting Language
DSL for MongoDB
Http Routing Language
Templates Language
DSL for Guice
Build Language
Tortoise
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19. Find more at
www.eclipse.org/Xtext/7languages.html
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