This document discusses domain specific languages (DSLs) and how they can be developed using Xtext. It provides examples of DSLs like regular expressions and SQL. It explains that DSLs allow problems to be expressed at the level of their domain, which allows domain experts to understand, validate, modify and develop programs. It then outlines how Xtext can be used to define the grammar of a DSL and generate rich editing support for the DSL in Eclipse. The document demonstrates a small DSL for modeling entities and properties and shows the live editing features provided by Xtext. It recommends Xtext as a framework for DSL development and provides information on tutorials and hiring.

1. Domain Specific Languages
in Eclipse with Xtext
redefine.digital.design: Helping you deal with complexity in VHDL and Verilog.
Dr. Ir. Hendrik Eeckhaut

2. About
CTO at Sigasi @heeckhau
Sigasi Studio: Eclipse based IDE for
VHDL and Verilog (digital hardware design)

3. • Domain Specific Languages (DSL)
• Xtext
• Demo
Overview

4. Domain specific language
“A domain-specific language (DSL) is
a computer language
specialized to a particular application domain”
Examples:
●Regular expressions: ^com.sigasi.*$
●SQL: SELECT * FROM table_name
https://en.wikipedia.org/wiki/Domain-specific_language

5. Cold beer
● Optimize energy efficiency
● Lots of variants (size, components)
● Cooling algorithms
○ Straight forward
○ Exceptions and interactions
○ Different for variants

6. Refrigerator control
Refrigerator description
Cooling algorithm
Code Generation
C-code
Documentation
Domain specific
simulator
http://www.voelter.de/data/presentations/RefrigeratorsAndDSLs.pdf
● Understand ?
● Validate ?
● Modify ?

7. Why DSLs
DSLs allow to express solutions at the
abstraction level of the problem domain.
⇒ Domain experts can understand, validate, modify
and develop DSL programs

8. How ?
Language definition (BNF)
Lexer and Parser
Abstract Syntax Tree
Linking, scoping, types
Validation
Code generator, interpreter

9. DSL Development Framework
Full DSL infrastructure (parser, linker, …)
Define DSL with a grammar language
⇩
+ Rich editing support for Eclipse, IntelliJ
IDEA and web browser

10. Rich editing
●Syntax coloring
●Type time validation
●Content assist (autocomplete)
●Code formatting
●Find references
●Rename
●Outline

11. How
Language definition (BNF)
Lexer and Parser
Abstract Syntax Tree
Linking, scoping, types
Validation
Code generator, interpreter
→ Xtext grammar
→ ANTLR
→ Eclipse EMF
(partially generated)
Java

12. To good to be true?
●Xtext contains default implementations for linking,
validation, …
●Can be fully customized
●Wired together with Dependency Injection
(Google Guice)

13. Demo
Small DSL to model entities and properties
1. datatype String
2.
3. entity Blog {
4. title: String
5. many posts: Post
6. }
7.
8. entity HasAuthor {
9. author: String
10. }
11.
12. entity Post extends HasAuthor {
13. title: String
14. content: String
15. many comments: Comment
16. }
17.
18. entity Comment extends HasAuthor {
19. content: String
20. }

14. Demo
1. datatype String
2.
3. entity Blog {
4. title: String
5. many posts: Post
6. }
7.
8. entity HasAuthor {
9. author: String
10. }
11.
12. entity Post extends HasAuthor {
13. title: String
14. content: String
15. many comments: Comment
16. }
17.
18. entity Comment extends HasAuthor {
19. content: String
20. }
elements : Type
(datatype or entity)
features : Feature
Domainmodel

15. Demo
1. datatype String
2.
3. entity Blog {
4. title: String
5. many posts: Post
6. }
7.
8. entity HasAuthor {
9. author: String
10. }
11.
12. entity Post extends HasAuthor {
13. title: String
14. content: String
15. many comments: Comment
16. }
17.
18. entity Comment extends HasAuthor {
19. content: String
20. }

16. Live Demo

17. Why Xtext
Very mature and complete system
Statically typed AST model
Open Source

18. Outro
DSLs?
●Very powerful
●Lots of work
Xtext
●Recommended DSL development framework
Sigasi is hiring: www.sigasi.com/careers

19. Hands on
Download Eclipse IDE for Java and DSL Developers
https://www.eclipse.org/downloads/
Start 15 Minutes tutorial from
https://eclipse.org/Xtext/documentation/102_domainmodelwalkthrough.html