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lib/Acme/List/CarCdr.pm  view on Meta::CPAN

# -*- Perl -*-
#
# c[ad]+r list-operation support for Perl, based on (car) and (cdr) and
# so forth of lisp fame, though with a limit of 704 as to the maximum
# length any such shenanigans.
#
# Run perldoc(1) on this file for additional documentation.

package Acme::List::CarCdr;

use 5.010000;
use strict;
use warnings;

use Carp qw(croak);

lib/Acme/List/CarCdr.pm  view on Meta::CPAN

  my $method = our $AUTOLOAD;
  if ( $method =~ m/::c([ad]{1,704})r$/ ) {
    my $ops   = reverse $1;
    my $self  = shift;
    my $ref   = \@_;
    my $start = 0;
    my $end;
    my $delve = 0;
    while ( $ops =~ m/\G([ad])(\1*)/cg ) {
      my $op = $1;
      my $len = length $2 || 0;
      if ( $op eq 'a' ) {
        if ( $len > 0 ) {
          for my $i ( 1 .. $len ) {
            if ( ref $ref->[$start] ne 'ARRAY' ) {
              croak "$method: " . $ref->[$start] . " is not a list";
            }
            $ref   = $ref->[$start];
            $start = 0;
          }
        }

t/carcdr.t  view on Meta::CPAN

eval 'use Test::Differences';    # display convenience
my $deeply = $@ ? \&is_deeply : \&eq_or_diff;

########################################################################

use Acme::List::CarCdr;
my $can = Acme::List::CarCdr->new;

# The reason for using names instead of numbers is that numbers may be
# returned by various array operations (length, index) that might be
# improperly confused with a test list that contains numbers instead of
# names. (Alternative: make the numbers contained by the list larger
# than the number of elements possible in the list.)
$deeply->( $can->car(qw/cat dog fish/), qw/cat/ );
$deeply->( [ $can->cdr(qw/cat dog fish/) ], [qw/dog fish/] );
$deeply->( $can->cddr(qw/cat dog fish/), qw/fish/ );

# Slightly more complicated, plus comparison with GNU CLISP 2.48
# [1]> (setf numlist '(("one" "two") ("three" "four") ("five" "six")))
my @numlist = ([q/one two/],[qw/three four/],[qw/five six/]);