Regular Right Part Grammars and Their Parsers
This paper in troduces an alternative to context-free
grammars called regular right part (RRP) 
grammars, which resemble PASCAL syntax diagrams.  Formally,
RRP grammars have production right parts, 
which are nondeterministic finite state machines (FSMs),
and, as a special case, regular expressions, 
since these can be converted to FSMs.  RRP grammars
describe the syntax of programming languages more 
concisely and more understandably than is possible with
CF grammars.  Also in troduced is a class of parsers, 
RRP LR(m, k) parsers, which includes the CF LR(k) parsers
and provides the same advantages.  Informally, 
an RRP LR(m, k) parser can determine the right end of
each handle by considering at most k symbols to 
the right of the handle and the left end, after the
right end has been found, by considering at most 
m symbols to the left of the handle.  A mechanism for
determining the left end is required because there 
is no bound on the length of the handle.
CACM October, 1977
LaLonde, W. R.
