Comment by dalke

That's "SMILES".

Yes. Here is the yacc grammar for the SMILES parser in the RDKit. https://github.com/rdkit/rdkit/blob/master/Code/GraphMol/Smi...

There's also one from OpenSMILES at http://opensmiles.org/opensmiles.html#_grammar . It has a shift/reduce error (as I recall) that I was not competent enough to fix.

I prefer to parser almost completely in the lexer, with a small amount of lexer state to handle balanced parens, bracket atoms, and matching ring closures. See https://hg.sr.ht/~dalke/opensmiles-ragel and more specifically https://hg.sr.ht/~dalke/opensmiles-ragel/browse/opensmiles.r... .