Hello pwagyi.
I wanted to try a on a flat string, with a regex that would do something like /A(.*)B.{N}C.{N}D/ where (.*) would be of length 0 (row), width (column) or width+1 (diagonal from top left to bottom right), and N would somehow be equal to that length.
I managed to do that using (??{ CODE }) patterns, which makes it possible to embed a new sub pattern in a regex while it is being run. But it is not available by default: you need use re "eval";.
Since the regex is build from the searched pattern, this ended up being a function that takes a pattern as a parameter, and returns a closure that will search that pattern in a grid. Maybe that's too many advanced perl feature for usable code ^^" .
use strict;
use warnings;
use re qw( eval );
use Data::Dump qw( pp );
sub finder_maker
{
my $pattern = shift;
my @chars = split //, $pattern;
die unless @chars > 1;
my ($first_char, $second_char, @tail) = @chars;
# Each character after the first two will be followed by (??{'.{'.le
+ngth($1).'}'})
# This means that the code '.{'.length($1).'}' will be run while the
+ regex is executed
# and be replaced by .{N} with N the length of the first interval
my $regex_tail = join "", map "(??{'.{'.length(\$1).'}'})$_", @tail;
# Return a sub that will search for this pattern in a grid
return sub {
my $data = $_[0];
my $width = @{ $data->[0] };
say "Searching for $pattern in:\n", pp($data);
# To avoid the string "ABCD" for
# A B
# C D
# giving a false row on BC, we add dummy values to onl
+y keep the actual rows as valid
# So we will have "AB__CD__" instead
my $string = "";
$string .= join "", @$_, "_" x @$_, "\n" for @$data;
my %directions = (
0 => "Row",
2*$width => "Column",
2*$width+1 => "Diagonal"
);
# Allow a distance that matches a row, column or diago
+nal for the first interval
my $first_interval = join "|", map ".{$_}", keys %dire
+ctions;
# Find the first char, then the second, separated by a
+n allowed interval
$string =~ /$first_char ($first_interval) $second_char
+ $regex_tail/xs
or say "Not found\n\n" and return { };
my $out = {
x => int($-[0]%(1+2*$width)),
y => int($-[0]/(1+2*$width)),
Direction => $directions{length $1}
};
say "Found:\n", pp($out), "\n\n";
return $out;
};
}
my $grid = [
[ qw( a a b a c ) ],
[ qw( a a a c f ) ],
[ qw( a f c 1 b ) ],
[ qw( a w x c z ) ],
[ qw( a q h q c ) ]
];
my $afx = finder_maker("afx");
$afx->($grid);
finder_maker("fc1b")->($grid);
my $smaller = [
['w', 'a'],
['a', 'q']
];
my $wq = finder_maker("wq");
$wq->($grid);
$wq->($smaller);
finder_maker("Nothing")->($smaller);
Searching for afx in:
[
["a", "a", "b", "a", "c"],
["a", "a", "a", "c", "f"],
["a", "f", "c", 1, "b"],
["a", "w", "x", "c", "z"],
["a", "q", "h", "q", "c"],
]
Found:
{ Direction => "Diagonal", x => 0, y => 1 }
Searching for fc1b in:
[
["a", "a", "b", "a", "c"],
["a", "a", "a", "c", "f"],
["a", "f", "c", 1, "b"],
["a", "w", "x", "c", "z"],
["a", "q", "h", "q", "c"],
]
Found:
{ Direction => "Row", x => 1, y => 2 }
Searching for wq in:
[
["a", "a", "b", "a", "c"],
["a", "a", "a", "c", "f"],
["a", "f", "c", 1, "b"],
["a", "w", "x", "c", "z"],
["a", "q", "h", "q", "c"],
]
Found:
{ Direction => "Column", x => 1, y => 3 }
Searching for wq in:
[["w", "a"], ["a", "q"]]
Found:
{ Direction => "Diagonal", x => 0, y => 0 }
Searching for Nothing in:
[["w", "a"], ["a", "q"]]
Not found
| 