GraSs: A Taxonomy of Grammar Smells

Organisation
global problems

Navigation
problems with navigating through the grammar

Structure
harmful relationships among grammar components

Proxy
indirect uses

Dependency
antipatterns in use

Complexity
metric-based smells

TooWide
the width (right hand side length) is too big

TooRamose
too much branching

TooRecursive
too much recursion

TooNested
groups are too deeply nested

TooTall
the height (distance from the root) is too big

Lonely
large non-modular grammar

TooModular
too many modules

Greedy
one module that does too much

Lazy
one module that does not do much

TooCoupled
low cohesion and/or high coupling

TooCoupled Edit!

Related smells: Weakened Modularity

Modularity can not only be broken or insufficient, it can also be weakened. A grammar split into several modules that have high coupling among them and low cohesion inside each of them, had better stayed as Lonely.

The GraSs taxonomy is a joint effort maintained by Dr. Vadim Zaytsev a.k.a. @grammarware. Page last updated in March 2021.