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Textpad and Regular Expressions

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A primer for more advanced search and replacing in Textpad.

A primer for more advanced search and replacing in Textpad.

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  • I like Textpad as a general-purpose editor AND a coding tool, because it all comes down to a *lot* of techie tools to control data. And text is just another form of data, really. When you're editing it.
  • Here's what you see when you fire up Textpad, probably.
  • You can have many files open at once. They'll appear in the Document Selector on the left, and in tabs along the top of the editing window.
  • Basic set-up follows...
  • I like to allow multiple instances so I can have a different set of files open in each. I like to replace Notepad because I hate Notepad. Putting a context menu shortcut in means you can right-click a file in Windows Explorer, and choose to open it in Textpad. Handy. (Also, if youselected the first 2 options, then choosing "Edit" when right-clicking a file will open the file in a new Textpad instance.)
  • These are the 3 main dialogue boxes we'll be using here. They have menu options under the "Search" menu as well.
  • Regular Expressions. Scary, but they really should be taught to children as young as 3 or 4, IMHO.
  • I'm fairly sure that the human brain runs on regular expressions. Probably in Perl.
  • You'll need some text open in Textpad to try this out on, of course.
  • Basically just brackets then. And dot, question mark, star, plus, pipe, caret and dollar. And backslash. If in doubt, you can always switch off regular expressions for a search. * Other regexp environments, e.g. unix, perl, PHP, etc allow other matches, but the principles are basically the same. See later slides for some other info.
  • I think of these like this: ? = "maybe" * = "any" + = "some"
  • Textpad is only case-sensitive if you set the "Match case" option when searching. If that was on, you'd need to use [a-zA-Z] to catch *all* letters, whatever case they were. Notice that the period on the last line is escaped, otherwise it would match *everything*.
  • * "Hello\\nworld" example assumes that "world" is at the start of the next line.
  • For want of a better word than "groups"
  • Answers: 1. Find any 3 digits at the start of a line 2. Find any 3 digits OR the word "Source" at the start of a line 3. Fine any *line* (the whole line) that ends in 3 digits (could be more than 3 - these would still get matched)
  • Probably the most confusing slide here. The next slide clarifies it a bit.
  • Also, nested brackets can get tricky - numbers are assigned in the order of *starting* brackets, I believe.
  • Cheat Sheet to be available soon
  • This will list the results in a search results pane in Textpad. You can double-click file names in this to open them. I'm not sure the best way to open *lots* of files though.
  • Where "Perl" can be read as "Textpad". For now. Oh, and here's a Perl RegExp to look for e-mail addresses (untested, there may be better ones): ^(\\w|\\-|\\_|\\.)+\\@((\\w|\\-|\\_)+\\.)+[a-zA-Z]{2,}$ (Won't work in Textpad though. Left as an exercise for the reader.) See also  http://www.ex-parrot.com/pdw/Mail-RFC822-Address.html

Transcript

  • 1. Textpad and Finding Things A primer for the uninitiated Graham Lally April 2012 graham.lally@ocsi.co.uk http://www.ocsi.co.uk/
  • 2. Coming up• Hello Textpad• Learning to love Regular Expressions• Other useful things
  • 3. Why Textpad? + Text-editing Lots of options http://www.textpad.com/ http://www.flickr.com/photos/eldholm/2354982554/ http://www.flickr.com/photos/grandmaitre/2387376806/
  • 4. Here are thefiles youhave open Write things here
  • 5. Configure > Preferences
  • 6. Basic set-up C Allow multiple instances to run C Replace Notepad C Put shortcut to Textpad on: Context MenuAlso set under "Editor" settings: C Use POSIX regular expression syntaxThis means we can use ( ) and { } instead of ( ) and { }
  • 7. Shortcuts to get started Search current file(s) F5 Search and replace F8 Search through a whole directory Ctrl + F5
  • 8. Regular ExpressionsWhy (oh why)? Regular expressions (REs / RegExps) let you search for a *range* of things in one go, rather than just a single thing. Old: Find "Kings Cross" RE: Find "King?s (Cross|X)" Kings X Kings X Kings X Kings X Kings Cross Kings Cross Kings Cross Kings Cross
  • 9. Why Regular Expressions?Also find: Any letter/number Any letter followed by any number Any number at the start/end of a line Any non-numbers etc.
  • 10. My first regular expression F5: C Regular expression Find: .a
  • 11. ".a""." is a special character in REs, meaning find any character (including letters, numbers, spaces and punctuation)So "..." finds any 3 characters in a row: abc, 123, y r, even ... .a Find any character followed by an "a", e.g. ba, 1a, %aAnd "a.c" will find abc, aac, a6c, a?c, a c, a[c, a-c, etc
  • 12. Characters to watch out forIn Textpad*, most characters do what they should.Some dont: . ? * + | [ ] ( ) { } ^ $To actually look for one of these, put a "" before it. e.g. ? (To look for a , use (* Other RegExp software may differ)
  • 13. Finding other things [...] Find any single character listed in the [ ] e.g. [abc][123] will match a1, c1, b2, c3, etc ...|... Find anything that matches before or after the | e.g. abc|123 will match abc and 123 Can also be more than 2: abc|123|xyz|000
  • 14. Counting thingsUse +, * or ? after a character to indicate how many times itshould occur: + Find one or more characters e.g. ab+c will find abc, abbc, abbbbbc, etc * Find zero or more characters e.g. ab*c will find ac, abc, abbc, abbbbbc, etc ? Find zero or one characters (i.e. "maybe") e.g. ab?c will find ac and abc, but not abbc
  • 15. Counting thingsUse {min,max} after a character to set your own limits e.g. ab{4,6}c will find abbbbc, abbbbbc and abbbbbbcmax is optional too e.g. ab{3,}c will find abbbc, abbbbbbbbbbbbbbbbbbc, etcmin isnt optional in Textpad, so use 0 instead e.g. ab{0,3}c will find ac, abc, abbc, abbc
  • 16. More character rangesTextpad also has some "named" ranges you can use, e.g. [:alpha:] Any letter [:digit:] Any digit [:blank:] Space or tab [:space:] Space, tab, return, line feed, et alThese go inside other [ ] e.g. [[:alpha:][:digit:]] finds any letter ornumber.See TextPads Help (available from the Find dialogue) formore.
  • 17. Character rangesWriting [0123456789] every time is silly.Instead, use [...-...] (dash) to specify a range of characters. e.g. [0-9] to find any single number [a-z] to find any letterThese can be combined with themselves, plus other characters e.g. [a-z0-9:.] to find any letter, number, colon or period
  • 18. Line and word endings n Lets you look for line breaks, e.g. Hellonworld will find Hello world < and > Match the start and end of a word ^ Match the start of a line e.g. ^: will find any colon at the start of a line $ Match the end of a line e.g. .$ will find any period at the end of a lineCombine these to match whole lines, e.g. ^?.*$ to match alllines that start with a question mark
  • 19. Getting more complicatedUse (...) to set up "groups" - these can then be checked andcounted in themselvese.g. (hello)+ will find hello, hellohello, hellohellohello, etc. (hello|bye){2} will find hellohello, byebye, hellobye and byehello Hello (Tom|Stefan|Emma) will look for any of the 3 names (t[io]ck){2}! will find ticktock!, tocktick!, ticktick!, and tocktock!
  • 20. More examples to figure outWhat do the following regular expressions do? ^[0-9]{3} ^(Source|[0-9]{3}) ^.*[0-9]{3}$
  • 21. Replacements F8As expected, Textpad will replace anything matched, with thetext specified.
  • 22. ReplacementsRemember though:The RE will (only/completely) match what youve typed.Textpad will replace whats been matched.Work out whats being matched and whats being replaced.e.g. We may want to  match (find) all lines ending with a ?, butonly replace the word before the ?
  • 23. ReplacementsA more useful example: [a-z]+[?!]$ Find any lines ending in letters, then ? or !We want to replace the letters (i.e. [a-z]+) with something, butkeep the ? or ! in placeBut we dont know which one to use when replacing...
  • 24. ReplacementsLuckily, we can refer to things that have been matched using(...) groups.Each group has its own number (in sequential order), and canbe inserted using ne.g. [a-z]+([?!])$ has one (...) group: 1 To replace the letters, we can use new word1 So hello! would become new word!
  • 25. ReplacementsTextpad uses 1 to 9 - which we can use wherever we wante.g. ([a-z]+) ([0-9]+) will match Pelham 123 Replacing this with 2 1 gives us 123 Pelham Replacing it with 22 gives us 123123(Be a bit careful if a (...) group is optional though, i.e. (...)? - ifits not found, your higher numbers will be wrong.)
  • 26. Phew...Can get tricky quickly, but remember: o Use the "Help" button o Use the "Find Next" button to check what your RE finds o Check the Cheat Sheet - http://bit.ly/textpadref
  • 27. Handy Tip 1: Multiple filesTo replace across many files, open all the files and tick "Alldocuments" when replacing:
  • 28. Handy Tip 2: Searching a folderTo look through (closed) files in a directory, use Ctrl + F5. Tick"Search subfolders" if folders are several layers deep.
  • 29. Handy Tip 3: Save everythingFinally:You can see which files have changed - these have a * next totheir filename.You can also save all changes to all open files using: File > Save All
  • 30. Other Textpad Useful BitsBlock select mode (Ctrl+Q, then B): Bookmarked lines:Cut/copy/deleteeverything selectedor bookmarked. Bookmarks
  • 31. http://xkcd.com/208/