Separation of Grammar and Semantics

Chevrotain is not limited like many other parsing libraries to only embedding actions inside the grammar, It can also automatically create a Concrete Syntax Tree Which can later be traversed using the visitor pattern.

This implements the design principle of Separation of Concerns which enables re-use of the same pure grammar for multiple purposes.

See example of two identical mathematical expression grammars:

• Firstly using embedded actions for semantics.
• Secondly using Separated semantics with a CST Visitor.