Regex Tips & Tricks

Presented on February 9th, 2017 at the OrlandoDevs meetup, Orlando, Florida, US.
https://www.meetup.com/OrlandoDevs/
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No matter whether you develop in PHP, Javascript, Ruby, Python or even HTML5, knowing how to write Regular Expressions is an essential skill for any developer. While a lot of people consider regexes to be black magic, used appropriately they're an awesome power-tool in your tool-belt. This talk will take you on a little walk on the wild side, introduce you to some of the more advanced features and teach you some useful tips and tricks of the trade.
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Links:
http://regexcheatsheets.com/
https://www.pluralsight.com/courses/regular-expressions-fundamentals

Transcript

1. Regular Expression Fundamentals Juliette Reinders Folmer @jrf_nl regexcheatsheets.com
3. Tips & Tricks Regex Basics
4. Tips & Tricks
5. Photo by Scott Liddell 1. If you need a screwdriver, why use a hammer ?
6. Jamie Zawinski, August 1997 alt.religion.emacs Some people, when confronted with a problem, think "I know, I'll use regular expressions." Now they have two problems.
7. 2. Not all matches are made in heaven... Photo by Petr Kratochvil
8. 3. Only Elephants Remember Everything © Photo by Juliette Reinders Folmer
9. (?:<expr>)
10. 4. Being negative isn't always a bad thing © Photo by Juliette Reinders Folmer
11. [^<chars>]
12. Less is the new more 5
13. / / o on one one. one.* one.*s one.*s. one.*s.? one.*s.?t one.*s.?t [a-z] one.*s.?t[a-z]+ one.*s.?t[a-z]+p = space one.*s.?t[a-z]+p one.*s.?t[a-z]+p . one.*s.?t[a-z]+p . {2,} one.*s.?t[a-z]+p .{2,}, one.*s.?t[a-z]+p .{2,}, We take one step forward, two steps back ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
14. / / We take one step back, two steps forward
15. <unit>{,m}? <unit>{n,}? <unit>{n,m}? <unit>*? <unit>+? <unit>?? Reluctant Quantifiers
16. 6. Explore Your Boundaries Photo by Miguel A.C. Domingo
17. Beginning of string Beginning of line Word boundaries End of string End of line
18. 7. The first love is the deepest...
19. /#?([A-F0-9]{6}|[A-F0-9]{3})/i
20. 8. What's this global village people keep talking about ???
21. Character classes PCRE POSIX [0-9] [^0-9] \d \D [[:digit:]] [^[:digit:]] [A-Za-z0-9_] [^A-Za-z0-9_] \w \W [[:word:]] [^[:word:]] [\t\f\r\n \v] [^\t\f\r\n \v] \s \S [[:space:]] [^[:space:]] [\t\f ] [^\t\f ] \h \H [[:blank:]] [^[:blank:]] [\r\n] [^\r\n] \v \V - -
22. déjà vu [\w ]+ French (fr) déjà vu [\w ]+ English (en)
23. 9. Escape and escape again
24. [(] [)] [|] [.] [?][*][+][{][}] [$] [/] \[ \] \( \) \| \. \? \* \+ \{ \} \^ \$ \\ \/ Literals [ ] ( ) | . ? * + { } ^ $ \ / (delimiter) Special Meaning Escaping Meta Characters
25. Java String.quote() quoteReplacement() PHP preg_quote() Matlab regexptranslate() Python re.escape() Objective-C escapedTemplateForString() escapedPatternForString() Ruby Regexp.escape() Regexp.quote() Escaping Arbitrary Strings // Javascript: function escapeInputString( str ) { return str.replace(/[[\]\/\\{}()|?+^$*.-]/g, "\\$&"); }
26. Matching a Literal Backslash \\\\ The actual backslash \\\\ Escaping for use in regex \\\\ String escape
27. Modify your behaviour 10
29. Setting: Unsetting: Combined: Apply to subpattern (non-capturing): Inline Modifiers (?i) (?-i) (?im-sx) (?i:subp)
31. Advanced Features Look around Named sub-matches Conditional sub-patterns Recursion Inline comments
32. Thanks! Any questions ? Slides: https://speakerdeck.com/jrf Course: https://www.pluralsight.com/courses/ regular-expressions-fundamentals