GraSs: A Taxonomy of Grammar Smells

Organisation
global problems

Navigation
problems with navigating through the grammar

Structure
harmful relationships among grammar components

Spaghetti
scattering details over the grammar

Shortage
incompleteness

Mixture
spicing the grammar with alien fragments

AlmostAlphabet
seemingly incomplete collections

ConfusingEntry
no starting symbol

Dead
nonterminal defined, but not referenced

Bottom
nonterminal referenced, but not defined

Debt
incompletenesses covered up by todo/fixme comments

Dead Edit!

Related smells: Unused Packages, Lava Flow, Obsolete Classes, Unutilized Abstraction, Dead Local Store, Dead Fields

All top (unused) nonterminals that were identified as not being the starting symbol(s) of the grammar, represent unreachable fragments. The programming counterpart of this smell is dead code and its variants.

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