Hi, this time I don't need so much as a problem solved, as rather just an advice about a more elegant solution. The scenario is: I read a file which contains likes of the following pattern: 
2 [...]
  [line1]
  [line2]
  [line3]
3 [...]
  [line1]
1 [...]
  [line1]
  [line2]
2 [...]
  [line1]
  [line2]

[download]

The output code should be a simple reordering, while keeping the lineXs under each numbered indicator-line.

1 [...]
  [line1]
  [line2]
2 [...]
  [line1]
  [line2]
  [line3]
2 [...]
  [line1]
  [line2]
3 [...]
  [line1]

[download]

(The ordering of the "2 ..." lines does not matter).

I currently do it by maintaining as hash structure which maps {number-indicator => [indicator-line, sub-lines, indicator-line, sub-lines, ...]} And then write this hash structure back to the file.

The key problem is how to read one block of those lines (indicator line + all following lines until the next indicator or EOF). I do this in a loop but it looks quite clumsy that way. Is there an elegant way to use some sort of grep/map/random magic functions to do this ?

(I cannot even write an example of what I tried because I cannot think of anything good :D)

Consider this item as more of a puzzle.

Thanks!

In reply to Looking for elegance by monkprentice

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