from
The Free On-line Dictionary of Computing (8 July 2008)
rl
Kent Wittenburg <[email protected]>.
The RL files contain code for defining {relational grammars}
and using them in a bottom-up parser to recognise and/or parse
expressions in Relational Languages.
The approach is a simplification of that described in
Wittenburg, Weitzman, and Talley (1991), Unification-Based
Grammars and Tabular Parsing for Graphical Languages, Journal
of Visual Languages and Computing 2:347-370. This code is
designed to support the definition and parsing of Relational
Languages, which are characterised as sets of objects standing
in user-defined relations.
Correctness and completeness is independent of the order in
which the input is given to the parser. Data to be parsed can
be in many forms as long as an interface is supported for
queries and predicates for the relations used in grammar
productions.
To date, this software has been used to parse recursive
pen-based input such as math expressions and {flow charts}; to
check for data integrity and design conformance in databases;
to automatically generate constraints in drag-and-drop style
graphical interfaces; and to generate graphical displays by
parsing relational data and generating output code.
requires: Common Lisp
ports: Allegro Common Lisp 4.1, Macintosh Common Lisp 2.0
(ftp://flash.bellcore.com/rl/).
(1992-10-31)