use strict;
use warnings;
use lib '../../';
use Carp ();
BEGIN {
FILTER_ONLY all => \&_filter_hyper,
code_no_comments => \&_filter_rest;
}
my ($ops) = map qr/(?:[Rr]?(?:$_))/, join '|', map quotemeta, ',', qw (
- + / * ** x % . & | ^ < > << >> <=> cmp lt gt eq ne le ge == != <= >=
);
sub _filter_hyper {
s/ ((?:<<|>>)~?) ($ops) (<<|>>) /$1'$2'$3/gx;
}
sub _filter_rest {
s{
(?<!<)
\[ (\.\.|\\)? ($ops) \]
(?= \s* (?! -> | \b(?:$ops)\b(?!>) | [;\)\]\}\>] ) )
}{
my $t = $1 || '';
$t = '..' if $t eq '\\';
"FAST::List::Gen::Perl6::_reduceWith '$t$2', "
}egx;
s{
(?<!<)
\[ (\.\.|\\)? ($ops) \]
(?!>)
}{
my $t = $1 || '';
$t = '..' if $t eq '\\';
"FAST::List::Gen::Perl6::_reduction('$t$2')"
}gxe;
s{
(?<![\$\@\%\&\*]) \b Z([Rr]?) \b (?:(~?)($ops))?
}{
my $rev = $1||$2 ? '~' : '';
$3 ? "|$rev'$3'|" : '|'
}gxe;
s{
(?<![\$\@\%\&\*]) \b X([Rr]?) \b (?:(~?)($ops))?
}{
my $rev = $1||$2 ? '~' : '';
$3 ? "x$rev'$3'x" : 'x'
}gxe;
}
my %cache;
sub _reduction {
my $str = "[@_]";
{return $cache{$str} || next}
local $@;
my $ret = eval {&FAST::List::Gen::glob($str)};
ref $ret eq 'CODE' or Carp::croak("not a generator glob: $str\n$@\n");
$cache{$str} = $ret;
}
sub _reduceWith {
goto &{_reduction shift}
}
sub filter {
my $str = shift;
for ($str) {
_filter_hyper;
_filter_rest;
}
return $str;
}
=head1 NAME
FAST::List::Gen::Perl6 - perl6 meta operators in perl5
=head1 SYNOPSIS
many of the features found in L<FAST::List::Gen> borrow ideas from perl6. however,
since the syntax of perl5 and perl6 differ, some of the constructs in perl5 are
longer/messier than in perl6. C< FAST::List::Gen::Perl6 > is a source filter that
makes some of C<FAST::List::Gen>'s features more syntactic.
the new syntactic constructs are:
zip: generator Z generator
zipwith: generator Z+ generator
cross: generator X generator
crosswith: generator X+ generator
hyper: generator <<+>> generator
hyper: generator >>+<< generator
hyper: generator >>+>> generator
hyper: generator <<+<< generator
reduce: [+] list
triangular reduction: [\+] list
or [..+] list
in the above, C< + > can be any perl binary operator.
here is a table showing the correspondence between the source filter constructs,
the native overloaded ops, and the operation expanded into methods and functions.
FAST::List::Gen::Perl6 FAST::List::Gen FAST::List::Gen expanded
<1..3> Z <4..6> ~~ <1..3> | <4..6> ~~ <1..3>->zip(<4..6>)
<1..3> Z. <4..6> ~~ <1..3> |'.'| <4..6> ~~ <1..3>->zip('.' => <4..6>)
<1..3> X <4..6> ~~ <1..3> x <4..6> ~~ <1..3>->cross(<4..6>)
<1..3> X. <4..6> ~~ <1..3> x'.'x <4..6> ~~ <1..3>->cross('.' => <4..6>)
<1..3> <<+>> <4..6> ~~ <1..3> <<'+'>> <4..6> ~~ <1..3>->hyper('<<+>>', <4..6>)
[+] 1..10 ~~ <[+] 1..10> ~~ reduce {$_[0] + $_[1]} 1 .. 10
[+]->(1..10) ~~ <[+]>->(1..10) ~~ same as above
[\+] 1..10 ~~ <[..+] 1..10> ~~ scan {$_[0] + $_[1]} 1 .. 10
[\+]->(1..10) ~~ <[..+]>->(1..10) ~~ same as above
except for normal reductions C< [+] >, all of the new constructs return a
generator.
you can flip the arguments to an operator with C< R > or C< r > and in some
cases C< ~ >
ZR. Zr. Z~.
XR. Xr. X~.
<<R.>> <<r.>> <<~.>>
[R.] [r.] n/a
[\R.] [\r.] n/a
when used without a following argument, reductions and triangular reductions
will return a code reference that will perform the reduction on its arguments.
my $sum = [+];
say $sum->(1..10); # 55
reductions can take a list of scalars, or a single generator as their argument.
only the left hand side of the zip, cross, and hyper operators needs to be a
generator. zip and cross will upgrade their rhs to a generator if it is an array.
hyper will upgrade it's rhs to a generator if it is an array or a scalar.
the source filter is limited in scope, and should not harm other parts of the code,
however, source filters are notoriously difficult to fully test, so take that
with a grain of salt. due to limitations of L<Filter::Simple>, hyper operators
will be filtered in both code and strings. all other filters should skip strings.
this code is not really intended for serious work, ymmv.
=head1 AUTHOR
Eric Strom, C<< <asg at cpan.org> >>
=head1 BUGS
report any bugs / feature requests to C<bug-list-gen at rt.cpan.org>, or through
comments / feedback / patches are also welcome.
=head1 COPYRIGHT & LICENSE
copyright 2009-2011 Eric Strom.
this program is free software; you can redistribute it and/or modify it under
the terms of either: the GNU General Public License as published by the Free
Software Foundation; or the Artistic License.
see http://dev.perl.org/licenses/ for more information.
=cut
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