{"id":78,"date":"2009-03-11T00:51:26","date_gmt":"2009-03-10T22:51:26","guid":{"rendered":"http:\/\/www.cetinkoca.com\/blog\/?p=78"},"modified":"2009-03-11T00:51:26","modified_gmt":"2009-03-10T22:51:26","slug":"regular-mess","status":"publish","type":"post","link":"https:\/\/www.cetinkoca.com\/blog\/regular-mess\/","title":{"rendered":"Regular Mess"},"content":{"rendered":"

Regular expressions can actually be quite messy. Don’t you think so? Well, think not before you see this…<\/p>\n

Below is a regular expression<\/a> used to validate email addresses according to the RFC 822<\/a> grammar. I just encountered this while browsing web today. Seriously, what the hell?<\/p>\n

(?:(?:rn)?[ t])*(?:(?:(?:[^()<>@,;:\\\".[] \u000000-\u000031]+(?:(?:(?:rn)?[ t]
\n)+|Z|(?=[[\"()<>@,;:\\\".[]]))|\"(?:[^\"r\\]|\\.|(?:(?:rn)?[ t]))*\"(?:(?:
\nrn)?[ t])*)(?:.(?:(?:rn)?[ t])*(?:[^()<>@,;:\\\".[] \u000000-\u000031]+(?:(?:(
\n?:rn)?[ t])+|Z|(?=[[\"()<>@,;:\\\".[]]))|\"(?:[^\"r\\]|\\.|(?:(?:rn)?[
\nt]))*\"(?:(?:rn)?[ t])*))*@(?:(?:rn)?[ t])*(?:[^()<>@,;:\\\".[] \u000000-\u0000
\n31]+(?:(?:(?:rn)?[ t])+|Z|(?=[[\"()<>@,;:\\\".[]]))|[([^[]r\\]|\\.)*
\n](?:(?:rn)?[ t])*)(?:.(?:(?:rn)?[ t])*(?:[^()<>@,;:\\\".[] \u000000-\u000031]+
\n(?:(?:(?:rn)?[ t])+|Z|(?=[[\"()<>@,;:\\\".[]]))|[([^[]r\\]|\\.)*](?:
\n(?:rn)?[ t])*))*|(?:[^()<>@,;:\\\".[] \u000000-\u000031]+(?:(?:(?:rn)?[ t])+|Z
\n|(?=[[\"()<>@,;:\\\".[]]))|\"(?:[^\"r\\]|\\.|(?:(?:rn)?[ t]))*\"(?:(?:rn)
\n?[ t])*)*<(?:(?:rn)?[ t])*(?:@(?:[^()<>@,;:\\\".[] \u000000-\u000031]+(?:(?:(?:
\nrn)?[ t])+|Z|(?=[[\"()<>@,;:\\\".[]]))|[([^[]r\\]|\\.)*](?:(?:rn)?[
\nt])*)(?:.(?:(?:rn)?[ t])*(?:[^()<>@,;:\\\".[] \u000000-\u000031]+(?:(?:(?:rn)
\n?[ t])+|Z|(?=[[\"()<>@,;:\\\".[]]))|[([^[]r\\]|\\.)*](?:(?:rn)?[ t]
\n)*))*(?:,@(?:(?:rn)?[ t])*(?:[^()<>@,;:\\\".[] \u000000-\u000031]+(?:(?:(?:rn)?[
\nt])+|Z|(?=[[\"()<>@,;:\\\".[]]))|[([^[]r\\]|\\.)*](?:(?:rn)?[ t])*
\n)(?:.(?:(?:rn)?[ t])*(?:[^()<>@,;:\\\".[] \u000000-\u000031]+(?:(?:(?:rn)?[ t]
\n)+|Z|(?=[[\"()<>@,;:\\\".[]]))|[([^[]r\\]|\\.)*](?:(?:rn)?[ t])*))*)
\n*:(?:(?:rn)?[ t])*)?(?:[^()<>@,;:\\\".[] \u000000-\u000031]+(?:(?:(?:rn)?[ t])+
\n|Z|(?=[[\"()<>@,;:\\\".[]]))|\"(?:[^\"r\\]|\\.|(?:(?:rn)?[ t]))*\"(?:(?:r
\nn)?[ t])*)(?:.(?:(?:rn)?[ t])*(?:[^()<>@,;:\\\".[] \u000000-\u000031]+(?:(?:(?:
\nrn)?[ t])+|Z|(?=[[\"()<>@,;:\\\".[]]))|\"(?:[^\"r\\]|\\.|(?:(?:rn)?[ t
\n]))*\"(?:(?:rn)?[ t])*))*@(?:(?:rn)?[ t])*(?:[^()<>@,;:\\\".[] \u000000-\u000031
\n]+(?:(?:(?:rn)?[ t])+|Z|(?=[[\"()<>@,;:\\\".[]]))|[([^[]r\\]|\\.)*](
\n?:(?:rn)?[ t])*)(?:.(?:(?:rn)?[ t])*(?:[^()<>@,;:\\\".[] \u000000-\u000031]+(?
\n:(?:(?:rn)?[ t])+|Z|(?=[[\"()<>@,;:\\\".[]]))|[([^[]r\\]|\\.)*](?:(?
\n:rn)?[ t])*))*>(?:(?:rn)?[ t])*)|(?:[^()<>@,;:\\\".[] \u000000-\u000031]+(?:(?
\n:(?:rn)?[ t])+|Z|(?=[[\"()<>@,;:\\\".[]]))|\"(?:[^\"r\\]|\\.|(?:(?:rn)?
\n[ t]))*\"(?:(?:rn)?[ t])*)*:(?:(?:rn)?[ t])*(?:(?:(?:[^()<>@,;:\\\".[]
\n\u000000-\u000031]+(?:(?:(?:rn)?[ t])+|Z|(?=[[\"()<>@,;:\\\".[]]))|\"(?:[^\"r\\]|
\n\\.|(?:(?:rn)?[ t]))*\"(?:(?:rn)?[ t])*)(?:.(?:(?:rn)?[ t])*(?:[^()<>
\n@,;:\\\".[] \u000000-\u000031]+(?:(?:(?:rn)?[ t])+|Z|(?=[[\"()<>@,;:\\\".[]]))|\"
\n(?:[^\"r\\]|\\.|(?:(?:rn)?[ t]))*\"(?:(?:rn)?[ t])*))*@(?:(?:rn)?[ t]
\n)*(?:[^()<>@,;:\\\".[] \u000000-\u000031]+(?:(?:(?:rn)?[ t])+|Z|(?=[[\"()<>@,;:\\
\n\".[]]))|[([^[]r\\]|\\.)*](?:(?:rn)?[ t])*)(?:.(?:(?:rn)?[ t])*(?
\n:[^()<>@,;:\\\".[] \u000000-\u000031]+(?:(?:(?:rn)?[ t])+|Z|(?=[[\"()<>@,;:\\\".[
\n]]))|[([^[]r\\]|\\.)*](?:(?:rn)?[ t])*))*|(?:[^()<>@,;:\\\".[] \u000000-
\n\u000031]+(?:(?:(?:rn)?[ t])+|Z|(?=[[\"()<>@,;:\\\".[]]))|\"(?:[^\"r\\]|\\.|(
\n?:(?:rn)?[ t]))*\"(?:(?:rn)?[ t])*)*<(?:(?:rn)?[ t])*(?:@(?:[^()<>@,;
\n:\\\".[] \u000000-\u000031]+(?:(?:(?:rn)?[ t])+|Z|(?=[[\"()<>@,;:\\\".[]]))|[([
\n^[]r\\]|\\.)*](?:(?:rn)?[ t])*)(?:.(?:(?:rn)?[ t])*(?:[^()<>@,;:\\\"
\n.[] \u000000-\u000031]+(?:(?:(?:rn)?[ t])+|Z|(?=[[\"()<>@,;:\\\".[]]))|[([^[
\n]r\\]|\\.)*](?:(?:rn)?[ t])*))*(?:,@(?:(?:rn)?[ t])*(?:[^()<>@,;:\\\".
\n[] \u000000-\u000031]+(?:(?:(?:rn)?[ t])+|Z|(?=[[\"()<>@,;:\\\".[]]))|[([^[]
\nr\\]|\\.)*](?:(?:rn)?[ t])*)(?:.(?:(?:rn)?[ t])*(?:[^()<>@,;:\\\".[]
\n\u000000-\u000031]+(?:(?:(?:rn)?[ t])+|Z|(?=[[\"()<>@,;:\\\".[]]))|[([^[]r\\]
\n|\\.)*](?:(?:rn)?[ t])*))*)*:(?:(?:rn)?[ t])*)?(?:[^()<>@,;:\\\".[] \u0000
\n00-\u000031]+(?:(?:(?:rn)?[ t])+|Z|(?=[[\"()<>@,;:\\\".[]]))|\"(?:[^\"r\\]|\\
\n.|(?:(?:rn)?[ t]))*\"(?:(?:rn)?[ t])*)(?:.(?:(?:rn)?[ t])*(?:[^()<>@,
\n;:\\\".[] \u000000-\u000031]+(?:(?:(?:rn)?[ t])+|Z|(?=[[\"()<>@,;:\\\".[]]))|\"(?
\n:[^\"r\\]|\\.|(?:(?:rn)?[ t]))*\"(?:(?:rn)?[ t])*))*@(?:(?:rn)?[ t])*
\n(?:[^()<>@,;:\\\".[] \u000000-\u000031]+(?:(?:(?:rn)?[ t])+|Z|(?=[[\"()<>@,;:\\\".
\n[]]))|[([^[]r\\]|\\.)*](?:(?:rn)?[ t])*)(?:.(?:(?:rn)?[ t])*(?:[
\n^()<>@,;:\\\".[] \u000000-\u000031]+(?:(?:(?:rn)?[ t])+|Z|(?=[[\"()<>@,;:\\\".[]
\n]))|[([^[]r\\]|\\.)*](?:(?:rn)?[ t])*))*>(?:(?:rn)?[ t])*)(?:,s*(
\n?:(?:[^()<>@,;:\\\".[] \u000000-\u000031]+(?:(?:(?:rn)?[ t])+|Z|(?=[[\"()<>@,;:\\
\n\".[]]))|\"(?:[^\"r\\]|\\.|(?:(?:rn)?[ t]))*\"(?:(?:rn)?[ t])*)(?:.(?:(
\n?:rn)?[ t])*(?:[^()<>@,;:\\\".[] \u000000-\u000031]+(?:(?:(?:rn)?[ t])+|Z|(?=[
\n[\"()<>@,;:\\\".[]]))|\"(?:[^\"r\\]|\\.|(?:(?:rn)?[ t]))*\"(?:(?:rn)?[ t
\n])*))*@(?:(?:rn)?[ t])*(?:[^()<>@,;:\\\".[] \u000000-\u000031]+(?:(?:(?:rn)?[ t
\n])+|Z|(?=[[\"()<>@,;:\\\".[]]))|[([^[]r\\]|\\.)*](?:(?:rn)?[ t])*)(?
\n:.(?:(?:rn)?[ t])*(?:[^()<>@,;:\\\".[] \u000000-\u000031]+(?:(?:(?:rn)?[ t])+|
\nZ|(?=[[\"()<>@,;:\\\".[]]))|[([^[]r\\]|\\.)*](?:(?:rn)?[ t])*))*|(?:
\n[^()<>@,;:\\\".[] \u000000-\u000031]+(?:(?:(?:rn)?[ t])+|Z|(?=[[\"()<>@,;:\\\".[
\n]]))|\"(?:[^\"r\\]|\\.|(?:(?:rn)?[ t]))*\"(?:(?:rn)?[ t])*)*<(?:(?:rn)
\n?[ t])*(?:@(?:[^()<>@,;:\\\".[] \u000000-\u000031]+(?:(?:(?:rn)?[ t])+|Z|(?=[[\"
\n()<>@,;:\\\".[]]))|[([^[]r\\]|\\.)*](?:(?:rn)?[ t])*)(?:.(?:(?:rn)
\n?[ t])*(?:[^()<>@,;:\\\".[] \u000000-\u000031]+(?:(?:(?:rn)?[ t])+|Z|(?=[[\"()<>
\n@,;:\\\".[]]))|[([^[]r\\]|\\.)*](?:(?:rn)?[ t])*))*(?:,@(?:(?:rn)?[
\nt])*(?:[^()<>@,;:\\\".[] \u000000-\u000031]+(?:(?:(?:rn)?[ t])+|Z|(?=[[\"()<>@,
\n;:\\\".[]]))|[([^[]r\\]|\\.)*](?:(?:rn)?[ t])*)(?:.(?:(?:rn)?[ t]
\n)*(?:[^()<>@,;:\\\".[] \u000000-\u000031]+(?:(?:(?:rn)?[ t])+|Z|(?=[[\"()<>@,;:\\
\n\".[]]))|[([^[]r\\]|\\.)*](?:(?:rn)?[ t])*))*)*:(?:(?:rn)?[ t])*)?
\n(?:[^()<>@,;:\\\".[] \u000000-\u000031]+(?:(?:(?:rn)?[ t])+|Z|(?=[[\"()<>@,;:\\\".
\n[]]))|\"(?:[^\"r\\]|\\.|(?:(?:rn)?[ t]))*\"(?:(?:rn)?[ t])*)(?:.(?:(?:
\nrn)?[ t])*(?:[^()<>@,;:\\\".[] \u000000-\u000031]+(?:(?:(?:rn)?[ t])+|Z|(?=[[
\n\"()<>@,;:\\\".[]]))|\"(?:[^\"r\\]|\\.|(?:(?:rn)?[ t]))*\"(?:(?:rn)?[ t])
\n*))*@(?:(?:rn)?[ t])*(?:[^()<>@,;:\\\".[] \u000000-\u000031]+(?:(?:(?:rn)?[ t])
\n+|Z|(?=[[\"()<>@,;:\\\".[]]))|[([^[]r\\]|\\.)*](?:(?:rn)?[ t])*)(?:
\n.(?:(?:rn)?[ t])*(?:[^()<>@,;:\\\".[] \u000000-\u000031]+(?:(?:(?:rn)?[ t])+|Z
\n|(?=[[\"()<>@,;:\\\".[]]))|[([^[]r\\]|\\.)*](?:(?:rn)?[ t])*))*>(?:(
\n?:rn)?[ t])*))*)?;s*)<\/code><\/p><\/blockquote>\n","protected":false},"excerpt":{"rendered":"

Regular expressions can actually be quite messy. Don’t you think so? Well, think not before you see this…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","enabled":false}}},"categories":[2,4],"tags":[40,41,43],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p5z32a-1g","_links":{"self":[{"href":"https:\/\/www.cetinkoca.com\/blog\/wp-json\/wp\/v2\/posts\/78"}],"collection":[{"href":"https:\/\/www.cetinkoca.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.cetinkoca.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.cetinkoca.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.cetinkoca.com\/blog\/wp-json\/wp\/v2\/comments?post=78"}],"version-history":[{"count":0,"href":"https:\/\/www.cetinkoca.com\/blog\/wp-json\/wp\/v2\/posts\/78\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.cetinkoca.com\/blog\/wp-json\/wp\/v2\/media?parent=78"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.cetinkoca.com\/blog\/wp-json\/wp\/v2\/categories?post=78"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.cetinkoca.com\/blog\/wp-json\/wp\/v2\/tags?post=78"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}