Run-length encoding

You are encouraged to solve this task according to the task description, using any language you may know.


Task

Given a string containing uppercase characters (A-Z), compress repeated 'runs' of the same character by storing the length of that run, and provide a function to reverse the compression.

The output can be anything, as long as you can recreate the input with it.



Example

 Input: WWWWWWWWWWWWBWWWWWWWWWWWWBBBWWWWWWWWWWWWWWWWWWWWWWWWBWWWWWWWWWWWWWW
 Output: 12W1B12W3B24W1B14W


Note: the encoding step in the above example is the same as a step of the Look-and-say sequence.




: encode(s) 
   StringBuffer new 
   s group apply(#[ tuck size asString << swap first <<c ]) ;
 
: decode(s)
| c i |
   StringBuffer new
   0 s forEach: c [
      c isDigit ifTrue: [ 10 * c asDigit + continue ]
      loop: i [ c <<c ] 0
      ]
   drop ;