Two recent developments in the field of formal languages are Parsing Expression Grammar (PEG) and packrat parsing. The PEG formalism is similar to BNF, but defines syntax in terms of recognizing strings, rather than constructing them. It is, in fact, precise specification of a backtracking recursivedescent parser. Packrat parsing is a general method to handle backtracking in recursive-descent parsers. It ensures linear working time, at a huge memory cost. This paper reports an experiment
Roman R. Redziejowski