Beefy Boxes and Bandwidth Generously Provided by pair Networks
Clear questions and runnable code
get the best and fastest answer
 
PerlMonks  

JSON saving regex?

by iaw4 (Scribe)
on Jan 27, 2012 at 00:59 UTC ( #950244=perlquestion: print w/ replies, xml ) Need Help??
iaw4 has asked for the wisdom of the Perl Monks concerning the following question:

my data structure contains some regexs deep inside, and I am trying to convert this structure to json alas, I don't know how to convince JSON to play ball:
use JSON qw(-convert_blessed_universally); my $test = qr/^[\w\@\.]+$/; print to_json($test);
gives me an error
encountered object '(?^:^\w\@\.+$)', but neither allow_blessed nor convert_blessed settings are enabled
what is the proper syntax to get this going? advice appreciated.
/iaw

Comment on JSON saving regex?
Download Code
Re: JSON saving regex?
by GrandFather (Cardinal) on Jan 27, 2012 at 02:32 UTC

    In essence you can't do that. $test contains a Perl regular expression object and JSON doesn't have an out-of-the-box way to deal with them.

    If you don't need to round trip the data, but are providing it for consumption elsewhere the allow_blessed function will suppresses the error, insert a 'null', and carry on:

    use strict; use warnings; use JSON qw(); my $test = {regex => qr/^[\w\@\.]+$/, str => "this is a string"}; my $json = JSON->new(); $json->allow_blessed(1); print $json->encode($test);

    Prints:

    {"str":"this is a string","regex":null}

    Update: and if you do want to round trip it with another Perl script then think about using YAML instead:

    use strict; use warnings; use YAML qw(); my $test = {regex => qr/\w+\W+(\w+)/, str => "this is a string"}; my $yamlStr = YAML::Dump($test); print "YAML: $yamlStr\n"; my $andBack = YAML::Load ($yamlStr); my ($secondWord) = $andBack->{str} =~ $andBack->{regex}; print "Second word is: $secondWord\n";

    Prints:

    YAML: --- regex: !!perl/regexp (?-xism:\w+\W+(\w+)) str: this is a string Second word is: is
    True laziness is hard work
Re: JSON saving regex?
by thargas (Chaplain) on Jan 27, 2012 at 13:16 UTC

    The problem is that qr/.../ produces a Regexp object (try ref(qr/.../)).

    If you know where all the regexes are in your structure, you could convert them all to strings before calling to_json() on them.

    Or you can do:
    { package Regexp; sub TO_JSON { my $regex = shift; $regex = "$regex"; return $regex; } my $json = JSON->new->convert_blessed; print $json->encode(qr/.../);
    as documented in JSON
      Excellent!

      Thanks for showing that this solution exists.

      (I hoped it would, but was too lazy to look it up :)

      Just one remark: I hope the OP doesn't expect that those RegExes always work in other languages than Perl.

Log In?
Username:
Password:

What's my password?
Create A New User
Node Status?
node history
Node Type: perlquestion [id://950244]
Approved by GrandFather
Front-paged by Corion
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others perusing the Monastery: (16)
As of 2014-07-23 16:54 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    My favorite superfluous repetitious redundant duplicative phrase is:









    Results (147 votes), past polls