Preface

Xtext is an open source Eclipse framework for implementing Domain Specific Languages together with their integration in the Eclipse IDE. Xtext allows you to implement languages quickly by covering all aspects of a complete language infrastructure, starting from the parser, code generator, or interpreter, up to a full Eclipse IDE integration, with all the typical IDE features such as editor with syntax highlighting, code completion, error markers, automatic build infrastructure, and so on.

This book will incrementally guide you through the very basics of DSL implementation with Xtext and Xtend, such as grammar definition, validation, and code generation. The book will then cover advanced concepts such as unit testing, type checking, and scoping. Xtext comes with good and smart default implementations for all these aspects. However, every single aspect can be customized by the programmer.

Although Java can be used for customizing the implementation of a DSL, Xtext fosters the use of Xtend, a Java-like programming language completely interoperable with the Java type system which features a more compact and easier to use syntax and advanced features such as type inference, extension methods, multi-line template strings and lambda expressions. For this reason, we will use Xtend throughout the book.

Most of the chapters have a tutorial nature and will describe the main concepts of Xtext through uncomplicated examples. The book also uses test driven development extensively. The last chapters will describe more advanced topics such as Continuous Integration and Xbase, a reusable Java-like expression language that ships with Xtext which can be used in your DSLs.

This book aims at being complementary to the official documentation, trying to give you enough information to start being productive in implementing a DSL with Xtext. This book will try to teach you some methodologies and best practices when using Xtext, filling some bits of information that are not present in the official documentation.

The chapters are meant to be read in order, since they typically refer to concepts that were introduced in the previous chapters.

All the examples shown in the book are available online, see the section Downloading the example code. We strongly suggest that you first try to develop the examples while reading the chapters and then compare their implementations with the ones provided by the author.