Text fragment for formatting a string (regular expression?)

Question

I am trying to create a textmate fragment that converts this:

HELLO WORLD<br />
SAY ANYTHING

For this:

hello world say anything

Any help?

Answer 1

With a little help from Allan Odgaard himself:

snippet

begin

  in:  ${1:Hello}

  out: ${1/\A\s+|\s+\Z|\s*\n\s*|(\<br\s*\/?\>)|(.)/(?1: :\L$2)/ig}

end

Test

begin

  in:  THIS IS<br />
  WORKING<BR>
  VERY NICELY<br/>

  EVEN WITH MULTIPLE<BR />
  LINE BREAKS!

  out: this is working very nicely even with multiple line breaks!

end

Regex matching Explanation

\A      beginning of buffer
\s+     followed by one or more whitespace

|       OR

\s+     one or more whitespace
\Z      followed by end of buffer

|       OR

\s*     zero or more whitespace
\n      followed by newline
\s*     followed by zero or more whitespace

|       OR

(       Capture to 1
  <br   Literal `<br'
  \s*   followed by zero or more whitespace
  \/?   followed by one or zero literal `/'
  >     followed by literal `>'
)       End capture

|       OR

(       Capture to 2
  .     Any character
)       End capture

Regex Replace Explanation

note : conditional replacements are unique to TextMate

(?1:    IF Capture 1 is found
        Insert space (' ')
  :     ELSE
  \L$2  Insert lowercase(Capture 2)
)       ENDIF

Regular Expression Modifier Explanation

i       case insensitive
g       global match/replace