gistfile1.txt

use v6;
#use Grammar::Tracer;

#  Question is that the parse on the following grammar NVL works fine when parsing expression 
#      "select nvl(toto,nvl(titi,tata) ) from dual ";
#  but it doesn't recognize nvl  when parsing this  expressioni ( difference is the simplequote) :
#       "select nvl(toto,nvl(titi,'tata') ) from dual ";
#  I don't understand why simple quote are not part of the regex <expr2txt>  defined as {:s .+}
#
#  correct result is :
#---
#｢select nvl(toto,nvl(titi,'tata') ) from dual ｣
# main => ｢select nvl(toto,nvl(titi,'tata') ｣
#  text => ｢select｣
#  nvl => ｢nvl(toto,nvl(titi,'tata') ｣
#   paraIn => ｢(｣
#   expr1 => ｢toto,nvl(titi｣
#   comma => ｢,｣
#   expr2 => ｢'tata'｣
#    expr2txt => ｢'tata'｣
#   paraOut => ｢)｣
# textfin => ｢) from dual ｣
#---
# 
# but getting 
#---
#｢select nvl(toto,nvl(titi,'tata') ) from dual ｣
# textfin => ｢select nvl(toto,nvl(titi,'tata') ) from dual ｣
#---



grammar NVL {

    rule  TOPNVL   { [<main>]* <textfin> }
      rule  main   { <text>  <nvl> }
        regex text   {:s .+?}
        rule  nvl    {:i  'nvl' <paraIn> <expr1> <comma> <expr2> <paraOut> }
          regex expr1    {:s .+?}
          rule expr2     {<nvl>|<expr2txt> }
          regex expr2txt   {:s .+?}
      regex textfin     {:s .+ }
      regex comma   {',' }
      regex paraIn  {'('}
      regex paraOut {')'}
}

 
### Parsing ok
my $cbl = "select nvl(toto,nvl(titi,tata) ) from dual ";
say "---";
say "Parsing : $cbl ---> OK" ;
say "---";
say NVL.parse($cbl, rule => 'TOPNVL');
say "---";
say "";

### Parsing nook
$cbl = "select nvl(toto,nvl(titi,'tata') ) from dual ";
say "---";
say "Parsing : $cbl ---> NOOK" ;
say "---";
say NVL.parse($cbl, rule => 'TOPNVL');
say "---";