Cut Points in PEG

Abstract

Parsing Expression Grammar (PEG) encodes a recursive-descent parser with limited backtracking. It has been recently noticed that in the situa tion when the parser is to explore several alternatives one after another, no further alternatives ne ed to be explored after the parser reached certain "cut point". This fact can be used to save both processing time and storage. The subject of the paper is identification of cut points, which can also help in producing better diagnostics.