Classes that handle Abstract Syntax Trees (ASTs).

The Metropolis meta-model consists of the frontend and a set of backend tools. The frontend parses meta-model files, creates Abstract Syntax Trees (ASTs), and applies a series of passes on the ASTs to make resolutions and semantic analysis. A Backend tool browses and analyzes the ASTs to generate a model appropriate for the backend. For example, a backend for a simulation tool in a particular language generates files that describe the meta-model design in the language.

@since Metropolis-1.0