/* ------------------------------------------------------------------------ */
/*                                                                          */
/* [styx.abs]                  Abstract Grammar                             */
/*                                                                          */
/* ------------------------------------------------------------------------ */

LANGUAGE styx

TOKENS

  Ide, Set, Seq

TYPES

  styx        = Start_Source(Source)

  Source      = root(Ide, QlxDfn*, OptCfg)

  OptCfg      = nul;
                cfg(Dfn*)

  QlxDfn      = xgrp(Ide);
                igrp(Ide);
                defn(QlxCat, QlxOpt, QlxGrp, Ide, QlxGrp, Exp)

  QlxCat      = letC;
                indC;
                ignC;
                comC;
                lanC;
                tokC

  QlxGrp      = non;
                igrp;
                grp(Ide)

  QlxOpt      = ignca;
                non

  Exp         = dyck(Exp, Exp, Exp);
                nul;
                opt(Exp);
                set(Set);
                conc(Exp, Exp);
                sequ(Seq);
                star(Exp);
                range(Exp, Exp);
                ident(Ide);
                union(Exp, Exp);
                diff(Exp, Exp);
                plus(Exp)

  Dfn         = defn(Cat, DfnOpt, Ide, Prd*)

  Cat         = bgnC;
                letC

  DfnOpt      = non;
                errnt

  Lay         = dft;
                rec;
                grp

  Prd         = prod(Lay, Ide, Mbr*)

  Mbr         = else;
                ntm(Ide);
                tkm(Seq)