Wrapping lines in a paragraph with header and footer lines

Question

Say I have a paragraph like this

line1
line2
line3

I want to select all and then transform like this

:start
line1
:end

:start
line2
:end

:start
line3
:end

Don't ask me why, we have some strange text transformation requirements. I could do it with Python but how can I do this in Vim.

I know I would start by selecting the block via V

Answer 1

The classic :s command can do stuff like this easily. e.g. type

:s/.*/:start\r&\r:end\r/

It looks like

:'<,'>s/.*/:start\r&\r:end\r/

on the command line if you select the area first, because '< and '> denote the visually selected range.

.* matches the entire line, \r is inserting newline, the & in the pattern represents the matched text (:h s/\r, :h s/\&)