Book Image

Implementing Domain-Specific Languages with Xtext and Xtend - Second Edition

By : Lorenzo Bettini
4 (1)
Book Image

Implementing Domain-Specific Languages with Xtext and Xtend - Second Edition

4 (1)
By: Lorenzo Bettini

Overview of this book

Xtext is an open source Eclipse framework for implementing domain-specific languages together with IDE functionalities. It lets you implement languages really quickly; most of all, it covers all aspects of a complete language infrastructure, including the parser, code generator, interpreter, and more. This book will enable you to implement Domain Specific Languages (DSL) efficiently, together with their IDE tooling, with Xtext and Xtend. Opening with brief coverage of Xtext features involved in DSL implementation, including integration in an IDE, the book will then introduce you to Xtend as this language will be used in all the examples throughout the book. You will then explore the typical programming development workflow with Xtext when we modify the grammar of the DSL. Further, the Xtend programming language (a fully-featured Java-like language tightly integrated with Java) will be introduced. We then explain the main concepts of Xtext, such as validation, code generation, and customizations of runtime and UI aspects. You will have learned how to test a DSL implemented in Xtext with JUnit and will progress to advanced concepts such as type checking and scoping. You will then integrate the typical Continuous Integration systems built in to Xtext DSLs and familiarize yourself with Xbase. By the end of the book, you will manually maintain the EMF model for an Xtext DSL and will see how an Xtext DSL can also be used in IntelliJ.
Table of Contents (25 chapters)
Implementing Domain-Specific Languages with Xtext and Xtend - Second Edition
Credits
Foreword
About the Author
Acknowledgments
About the Reviewer
www.PacktPub.com
Preface
Preface to the second edition
14
Conclusions
Bibliography
Index

Providing a library


Our implementation of SmallJava does not yet allow to make references to types such as Object, String, Integer, and Boolean We could use these to declare variables initialized with constant expressions. In this section, we show how to create a library with predefined types.

One might be tempted to hardcode these classes/types directly in the grammar, but this is not the best approach. There are many reasons for not doing that; mostly, that the grammar should deal with syntax only. Moreover, if we hardcoded, for example, Object in the grammar, we would only be able to use it as a type, but what if we wanted Object to have some methods? We would not be able to express that in the grammar.

Instead, we will follow the library approach (see also the article Zarnekow 2012-b). Our language implementation will provide a library with some classes, for example, Object, String, and so on, just like Java does. Since Xtext deals with EMF models, this library could consist of any EMF...