Does anyone have a script that will convert \xymatrix to tikzcd?

Question

I have a long set of lecture notes where the commutative diagrams are written in xy using the \xymatrix format. I would like to switch over to tikz-cd. The syntax for the two are pretty similar with some minor differences, so it is conceivable to me that someone has either written, or could easily write, a script that will automatically convert all \xymatrix{...} occurrences to a tikz-cd format that works for all non-exotic commutative diagrams. If somebody knows of such a script or can give me such a script, I would be very happy!

Note that I am willing to do the effort of fixing diagrams that involve curved lines or other non-standard things if that is too hard for a script.

I am not working on a unix machine although I have access to a Macbook that I could open in unix if necessary.

Here is a sample in \xymatrix{...}

\xymatrix{\Delta_{q-2}\ar[r]^{F_{q-1}^i}\ar[d]_{F_{q-1}^{j-1}}& \Delta_{q-1}\ar[d]^{F_q^j}\\
 \Delta_{q-1}\ar[r]_{F_{q}^i} & \Delta_q}

And the corresponding tikz-cd

\begin{tikzcd}
\Delta_{q-2}\ar{r}{F_{q-1}^i}\ar{d}[swap]{F_{q-1}^{j-1}}& \Delta_{q-1}\ar{d} {F_q^j}\\ 
\Delta_{q-1}\ar{r}[swap]{F_{q}^i} & \Delta_q
\end{tikzcd}

Please note that I have at least 50 occurrences of xymatrix so I would like a script that converts a whole file.

Answer 1

It's not extremely pretty, but it works:

#!/usr/bin/perl

use strict;
use warnings;
use feature qw/say/;
use Regexp::Common;

my $file = 'a.tex';             # Change this to your filename
open my $fh, '<', $file;
my $content = do { local $/; <$fh> };

my $bal_rx = $RE{balanced}{-parens=>'{}'};
my $ar_rx = qr/\s*
            \\ar
            (?<dash> @\{-->\} )?
            \[(?<dir> [udlr]+ )\]
            (?: (?<p1> [_^] ) (?<ar1> $bal_rx) )?
            (?: (?<p2> [_^] ) (?<ar2> $bal_rx) )?
            \s*/x;

sub conv_block {
    my $x = shift;
    my @s;
    while ($x =~ s/$ar_rx//){
        my $dir = $+{dir};
        my $dash = $+{dash} ? '[dashed]' : '';
        my ($t1, $t2) = ('', '');
        if ($+{ar1}) {
            $t1 = $+{ar1};
            $t1 = '[swap]' . $t1 if $+{p1} eq '_';
        }
        if ($+{ar2}) {
            $t1 = $+{ar2};
            $t2 = '[swap]' . $t2 if $+{p2} eq '_';
        }
        push @s, "\\ar${dash}{$dir}$t1$t2";
    }
    return $x . ' ' . (join ' ', @s);
}

sub conv_matrix {
    my $matrix = shift;
    $matrix =~ s/^\{(.*)\}$/$1/s;
    my @rows = split /\s* \\\\ \s*/x, $matrix;
    my @cols = map { [split /\s* & \s*/x, $_] } @rows;
    my $res = '';
    $res .= "\\begin{tikzcd}\n";
    $res .= join " \\\\\n", map { join " &\n", map {conv_block $_} @$_ } @cols;
    $res.= "\n\\end{tikzcd}\n";
    return $res;
}

$content =~ s/\\xymatrix $bal_rx/conv_matrix $1/gxe;
open my $out, '>', "${file}.new";
print $out $content;

You need Perl and the Regexp::Common library. I haven't extensively tested it, but it works in simple cases.