Chapter 7. External DSL implementation artifacts

External DSLs, like the internal ones, have a layer of abstraction on top of an existing domain model. Where they differ is how they implement the layer. External DSLs build their own language-processing infrastructure: the parsers, the lexers, and the processing logic.

We’re going to start with a discussion of the overall architecture of the processing infrastructure of an external DSL. The internal DSLs get this infrastructure free from the underlying host language, but the external DSLs need to build them from the ground up. First, we’re going to look at hand-written parsers, and then move on to develop your first custom external DSL using the ANTLR parser generator. In the final section of the chapter, we’ll look at a different paradigm of DSL development: the model-driven approach of the Eclipse Modeling Framework (EMF), using Xtext, as a comprehensive environment for external DSL development. Figure 7.1 provides a roadmap of our progress through the chapter.

In this chapter, you’ll learn how to develop a language-processing infrastructure using the tools available on the market today. When you’re done, you can use this infrastructure to develop your own DSL processor.

7.1. Anatomy of an external DSL

7.2. The role of a parser in designing an external DSL

7.3. Classifying parsers

7.4. Tool-based DSL development with Xtext

7.5. Summary

7.6. References