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

Custom formatting


An editor for a DSL should provide a mechanism for rearranging the text of the program in order to improve its readability, without changing its semantics. For example, nested regions inside blocks should be indented, and the user should be able to achieve that with a menu.

Besides that, implementing a custom formatter has also other benefits, since the formatter is automatically used by Xtext when you change the EMF model of the AST. If you tried to apply the quickfixes we implemented in Chapter 4, Validation, you might have noticed that after the EMF model has changed, the editor immediately reflects this change. However, the resulting textual representation is not well formatted, especially for the quickfix that adds the missing referred entity.

In fact, the EMF model representing the AST does not contain any information about the textual representation, that is, all white space characters are not part of the EMF model (after all, the AST is an abstraction of the actual...