Re: Replacing sed for zsh portability

[Peter Stephenson <pws@csr.com>]

DervishD wrote:
> #<=
> # This is an example of documentation
> # Here are more lines
> #
> # Yet even more lines here
> ...
> #=>
> 
>     Since I cannot use sed for the entire work unless I complicate
> the script (doing multiple substitutions and the like), I want to get
> rid of the current script and doing all the job in ZSH. It doesn't
> matter if it is very slow, speed here is not an issue.
> 
>     Can this be done in zsh easily or the only way is to use a while
> loop to ignore lines before the delimiter and another to process the
> documentation itself?

A while loop is the obvious way.  You can read in the entire file
(file="$(<file)") and substitute on that.  My example succeeded with this:

print -r ${(S)file//$'\n#<='*$'\n#=>'}

although the following is better since it takes account of the fact
that a comment may be at the start: 

print -r ${(S)file//($'\n'|(#s))\#\<\=*$'\n#=>'}

This requires extended_glob.

>     Another question, related to this. It seems that the X|Y glob
> operator doesn't work left-to-right, but shortest-first. If I do
> this:
> 
>     print ${line#\#(<=|=>| |)}
> 
>     then the 'nothing' at the end is used as the match, and the
> delimiters are not matched.

You're missing the fact that your substitution is of the form ${line#...}.
This is explicitly documented to remove the shortest matching chunk at
the head of the line.  Try adding another "#":

    print ${line##\#(<=|=>| |)}

-- 
Peter Stephenson <pws@csr.com>                  Software Engineer
CSR PLC, Churchill House, Cambridge Business Park, Cowley Road
Cambridge, CB4 0WZ, UK                          Tel: +44 (0)1223 692070


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