If you tried to apply one of 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 (as shown in the following screenshot, where we applied the quickfix which adds the missing entity FooBar).
In general, 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 program).
Xtext keeps track of such information in another in-memory model called the node model . The node model carries the syntactical information, that is, offset and length in the textual document. However, when we manually change the EMF model, we do not provide any formatting directives, and Xtext uses the default formatter to get a textual representation of the modified or added...
