regular expressions 101

[phitsc]

While working with regular expressions today I stumbled over regular expressions 101. Not only does it test your regular expression as you type, but it also picks it apart and explains it to you piece by piece. Amazing!

[wraith808]

There's also https://www.debuggex.com/?re=&str=

But personally, I use RegexBuddy.  It costs.  But I haven't found anything as robust.  And I'm willing to pay for my sanity when regularly confronted by regex like this...

Code: Text [Select]

1. (?imnx)                                                                         #multiline mode, explicit captures only, with comments
2. ^                                                                                       #start at beginning
3. \s*                                                                                     #optional whitespace
4. (                                           #start optional group
5.         (                                       #begin OR
6.                 (part|item|exhibit|note)            #match from a specific set of words
7.                 |                                   # OR
8.                 (?<unknown>\w+)                     #match any old word
9.         )                                       #end OR
10.         \s{1,2}                                 #limited whitespace between each one. capture certain specific ones.
11. )?                                                                  #end optional group
12. \(?                                         # optional open parenthesis
13. (                                           # begin OR
14.         ([\d]{1,2}\w?)                          # 1-2 numbers with an optional letter on the end
15.         |                                       # OR
16.         ([ivx]{1,3})                            # 1-2 roman numeral letters
17.         |                                       # OR
18.         ([a-z])                                 # 1 letters
19. )                                           # end OR
20. \)?                                         # optional end paren
21. \s{0,2}                                                                         # optional whitespace
22. (                                           # begin OR
23.         ([\.](?(unknown)(\s{2,})|(\s+)))        # a period followed by at least one space if no unknown header, at least two spaces if unknown header
24.         |                                       # OR
25.         ([:]\s+)                                # colon followed by at least one space
26.         |                                       # OR
27.         (\p{Pd}+)                               # some number of dashes
28.         |                                       # OR
29.         (\)\s+)                                 # close paren followed by at leaset one space
30. )                                                                       # end OR
31. \s*                                         #optional whitespace

At least it's commented... right?

[phitsc]

...
At least it's commented... right?

-wraith808 (August 20, 2014, 02:48 PM)

On the right, you mean

[wraith808]

...
At least it's commented... right?

-wraith808 (August 20, 2014, 02:48 PM)

On the right, you mean

-phitsc (August 20, 2014, 02:52 PM)

amirite?

Seriously though, it's pretty impressive... though it doesn't seem to recognize global flags as in the beginning of that regex I posted.  It also doesn't seem to recognize line comments.  But that's a horrendous example... and what it does match, for a web app that costs nothing?  Impressive.

[Nod5]

Nice find! Let me regexpress my gratitude to phitsc for posting about it.