Xtext uses the MWE2 DSL to configure the generation of its artifacts; the default generated .mwe2 file already comes with good defaults, thus, for the moment, we will not modify it. However, it is interesting to know that by tweaking this file we can request the Xtext generator to generate support for additional features, as we will see later in this book.
During the MWE2 workflow execution, Xtext will generate artifacts related to the UI editor for your DSL, but most important of all, it will derive an ANTLR specification from the Xtext grammar with all the actions to create the AST while parsing. The classes for the nodes of the AST will be generated using the EMF framework (as explained in the next section).
The generator must be run after every modification to the grammar (the .xtext file). The whole generator infrastructure relies on the Generation Gap Pattern
(Vlissides 1996). Indeed, code generators are fine, but when you have to customize the generated code: subsequent...
