{"id":194,"date":"2014-07-23T00:45:27","date_gmt":"2014-07-23T00:45:27","guid":{"rendered":"http:\/\/www.minotaurdesign.com\/blog\/?p=194"},"modified":"2014-07-23T00:46:25","modified_gmt":"2014-07-23T00:46:25","slug":"notes-codestock-2014%e2%80%b2s-regular-expressions-presentation","status":"publish","type":"post","link":"https:\/\/www.minotaurdesign.com\/blog\/2014\/07\/23\/notes-codestock-2014%e2%80%b2s-regular-expressions-presentation\/","title":{"rendered":"Notes from CodeStock 2014\u2032s \u201cRegular Expressions\u201d presentation"},"content":{"rendered":"

Brian Friesen’s talk on Regular Expressions was probably my favorite of the conference. You gotta admire a guy who builds a regular expression engine to properly demo and train folks up on the ‘devil’s language’ (as I and others I’ve known have called it)… Folks that hate regex and those that live and breathe the stuff all got something from the session. Good stuff.<\/p>\n

Regular Expressions – now you have two problems<\/h3>\n

Brian Friesen
\n@brianfriesen<\/a><\/p>\n

Works at Quicken Loans (side note, I used QL last year – hands down the best UX I’ve ever seen in a mortgage product\/service)<\/p>\n

github.com\/QuickenLoans\/RegExpose<\/a><\/p>\n

Regexper.com<\/a><\/p>\n

Regular-expressions.info<\/a><\/p>\n

The Bible:<\/strong>
\nMastering Regular Expressions<\/em> by Jeffery Friedl
\n– can read the first 2\/5 of the book and you have enough
\n———————————————————————–<\/p>\n

1. RegEx are hierarchical<\/strong><\/p>\n

Root node = the whole expression<\/p>\n

ABC would tree out like this:<\/p>\n

ABC – root
\nA – character literal
\nB – character literal
\nC – character literal<\/p>\n

2. RegEx do their thing sequentially<\/strong><\/p>\n

A RegEx will match if each of its child nodes matches in sequence
\nAfter a match, the RegEx engine will continue trying to find further matches until it has covered the entire string.<\/p>\n

RegEx are by default case-sensitive<\/strong><\/p>\n

Character classes are surrounded by square brackets<\/strong>
\n– for a range, use a dash.
\n– if you need a dash in the match, put it at the beginning of your set within square brackets
\n– you can also include specific characters or numbers to match against
\n– can include a-z and A-Z, or you can pass an additional param to ignore case
\n– a negated character class = add a “^” carat character before a match. ie [^a-f0-9] would ignore a-f<\/p>\n

Shorthand matches<\/strong>
\n– \\d is the same as [0-9]
\n– \\D is the same as [^0-9]
\n– \\s matches whitespace chars
\n– \\w is the same as any word character, meaning [A-Za-z0-9_]
\n– . matches any character, depending on options (ie except for new line character)<\/p>\n

Alternation<\/strong>
\n(it’s a pipe dream)<\/p>\n

| character means “or”
\n– linos|tigers|bears ‘lions’ would match, but regExp doesn’t know if its the BEST match, so it saves state (a breadcrumb) and moves to check the other choices.
\n– if a match hits on the last option in a set of choices, no state will be saved, no breadcrumbs etc.<\/p>\n

Quantifiers (quantifiers are always AFTER)<\/strong>
\n(Because sometimes, quantity trumps quality)<\/p>\n

Greedy Quantifiers<\/strong> (greedy means quantifier always wants more, ie. will keep going)
\n——————
\n– ? = optional
\n– * = will match zero, will match many
\n– PO*P would match “PP” as well as “POOP”
\n– + = must match at least once to succeed
\n– NO+! would match “NO!” as well as “NOOOOOOOOOOO!”
\n– {} = match a specific number of things
\n– \\d{3} = this means match exactly 3 digits
\n– \\d{3,15} = this means match at least 3, but up to 15
\n– \\d{3,} = this means match at least 3 with no high end limit<\/p>\n

Ultimate lazy quantifier: .*<\/p>\n

Causion against using “*.” – can lead to a match failing since the greedy ‘any character as many as possible’ matching could lead to skipping more specific matches after the *.<\/p>\n

Lazy Quantifiers <\/strong>– will only match as much as is needed, without going overboard
\nOnce a match is made it will pass control to the next match paramater until it’s needed again…
\n—————-
\n.*? = Lazy
\n{3,5}? = also Lazy (in this case, once 3 digits were matched, the next node in regexp would be matched)<\/p>\n

– ab.*?cd would match “abc12345cd” with the lazy quantifier returning to the ‘c’ character repeatedly before going back to the next number character<\/p>\n

More alternation<\/strong>
\n—————-
\n(?:white|dog|brick) house
\n– match against “dog house”<\/p>\n

Quantifers + grouping<\/strong>
\n———————
\n(?:NaN)+
\n– match against “NaNNaNNaNNaNNaN”<\/p>\n","protected":false},"excerpt":{"rendered":"

Brian Friesen’s talk on Regular Expressions was probably my favorite of the conference. You gotta admire a guy who builds a regular expression engine to properly demo and train folks up on the ‘devil’s language’ (as I and others I’ve known have called it)… Folks that hate regex and those that live and breathe the … Continue reading Notes from CodeStock 2014\u2032s \u201cRegular Expressions\u201d presentation<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4,17],"tags":[48,45,46,47,43,44],"class_list":["post-194","post","type-post","status-publish","format-standard","hentry","category-development","category-javascript","tag-filtering","tag-matching","tag-patterns","tag-programming","tag-regex","tag-regular-expression"],"yoast_head":"\nNotes from CodeStock 2014\u2032s \u201cRegular Expressions\u201d presentation - Minotaur Design<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.minotaurdesign.com\/blog\/2014\/07\/23\/notes-codestock-2014\u2032s-regular-expressions-presentation\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Notes from CodeStock 2014\u2032s \u201cRegular Expressions\u201d presentation - Minotaur Design\" \/>\n<meta property=\"og:description\" content=\"Brian Friesen’s talk on Regular Expressions was probably my favorite of the conference. You gotta admire a guy who builds a regular expression engine to properly demo and train folks up on the ‘devil’s language’ (as I and others I’ve known have called it)… Folks that hate regex and those that live and breathe the … Continue reading Notes from CodeStock 2014\u2032s \u201cRegular Expressions\u201d presentation\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.minotaurdesign.com\/blog\/2014\/07\/23\/notes-codestock-2014\u2032s-regular-expressions-presentation\/\" \/>\n<meta property=\"og:site_name\" content=\"Minotaur Design\" \/>\n<meta property=\"article:published_time\" content=\"2014-07-23T00:45:27+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2014-07-23T00:46:25+00:00\" \/>\n<meta name=\"author\" content=\"minoblogger\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"minoblogger\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"3 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\\\/\\\/www.minotaurdesign.com\\\/blog\\\/2014\\\/07\\\/23\\\/notes-codestock-2014%e2%80%b2s-regular-expressions-presentation\\\/#article\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/www.minotaurdesign.com\\\/blog\\\/2014\\\/07\\\/23\\\/notes-codestock-2014%e2%80%b2s-regular-expressions-presentation\\\/\"},\"author\":{\"name\":\"minoblogger\",\"@id\":\"https:\\\/\\\/www.minotaurdesign.com\\\/blog\\\/#\\\/schema\\\/person\\\/0a7e35e42a4936a2196bb0e9d1506725\"},\"headline\":\"Notes from CodeStock 2014\u2032s \u201cRegular Expressions\u201d presentation\",\"datePublished\":\"2014-07-23T00:45:27+00:00\",\"dateModified\":\"2014-07-23T00:46:25+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\\\/\\\/www.minotaurdesign.com\\\/blog\\\/2014\\\/07\\\/23\\\/notes-codestock-2014%e2%80%b2s-regular-expressions-presentation\\\/\"},\"wordCount\":623,\"commentCount\":0,\"publisher\":{\"@id\":\"https:\\\/\\\/www.minotaurdesign.com\\\/blog\\\/#\\\/schema\\\/person\\\/0a7e35e42a4936a2196bb0e9d1506725\"},\"keywords\":[\"filtering\",\"matching\",\"patterns\",\"programming\",\"regex\",\"regular expression\"],\"articleSection\":[\"Development\",\"Javascript\"],\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"CommentAction\",\"name\":\"Comment\",\"target\":[\"https:\\\/\\\/www.minotaurdesign.com\\\/blog\\\/2014\\\/07\\\/23\\\/notes-codestock-2014%e2%80%b2s-regular-expressions-presentation\\\/#respond\"]}]},{\"@type\":\"WebPage\",\"@id\":\"https:\\\/\\\/www.minotaurdesign.com\\\/blog\\\/2014\\\/07\\\/23\\\/notes-codestock-2014%e2%80%b2s-regular-expressions-presentation\\\/\",\"url\":\"https:\\\/\\\/www.minotaurdesign.com\\\/blog\\\/2014\\\/07\\\/23\\\/notes-codestock-2014%e2%80%b2s-regular-expressions-presentation\\\/\",\"name\":\"Notes from CodeStock 2014\u2032s \u201cRegular Expressions\u201d presentation - 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