RE: Your input is needed: Use regexp to match content

[Cook, Malcolm]

Hi Ole,

> I am really happy about the {= =} construct (thanks Malcolm - it was a 
> brilliant
> idea).

You're most welcome.  I use it myself all the time 😉

> But it is a bit cumbersome to use that when a regexp would just match.
> 
> echo 2023-10-29 |
>   parallel echo 'Year={=s/(....)-..-../$1/=} Month={=s/....-(..)-../$1/=} Day 
> of
> month={=s/....-..-(..)/$1/=}'
> 
> In this case you could use --colsep:
> 
> echo 2023-10-29 |
>   parallel --colsep - echo 'Year={1} Month={2} Day of month={3}'

I don't yet see a motivating example that cannot make use of perl's named 
capture groups.

Example:

echo 2023-10-29 |  parallel echo 
'{=s/(?<YYYY>....)-(?<MM>..)-(?<DD>..)/Year=$+{YYYY} Month=$+{MM} Day of 
month=$+{DD}/=}'
Year=2023 Month=10 Day of month=29

> But when it gets more complex you cannot:
> 
> echo 2023-10-29T23:59:59+01:00 |
>   parallel echo ' \
>   Y={=s/(....)-..-..T..:..:..[-+]..:../$1/=} \
>   M={=s/....-(..)-..T..:..:..[-+]..:../$1/=} \
>   D={=s/....-..-(..)T..:..:..[-+]..:../$1/=} \
>   H={=s/....-..-..T(..):..:..[-+]..:../$1/=} \
>   M={=s/....-..-..T..:(..):..[-+]..:../$1/=} \
>   S={=s/....-..-..T..:..:(..)[-+]..:../$1/=} \
>   Z={=s/....-..-..T..:..:..[-+](..:..)/$1/=}
>   '
> or:
> 
> echo 2023-10-29T23:59:59+01:00 |
>   parallel --rpl '{D(.)} s/(....)-(..)-(..)T(..):(..):(..)[-+](..:..)/$$$1/' \
>     echo Y={D1} M={D2} D={D3} H={D4} M={D5} S={D6} Z={D7}
> 
> But wouldn't it be nice if you could simply match the line (THIS IS ONLY AN
> IDEA):
> 
> echo 2023-10-29T23:59:59+01:00 |
>   parallel --match '((....)-(..)-(..))T((..):(..):(..))[-+](..:..)' \
>     echo YMD={1} Y={2} M={3} D={4} HMS={5} H={6} M={7} S={8} Z={9}

But you can do this already:

echo 2023-10-29T23:59:59+01:00  | parallel echo 
'{=s/((....)-(..)-(..))T((..):(..):(..))[-+](..:..)/YMD=$1 Y=$2 M=$3 D=$4 
HMS=$5 H=$6 M=$7 S=$8 Z=$9/=}'

YMD=2023-10-29 Y=2023 M=10 D=29 HMS=23:59:59 H=23 M=59 S=59 Z=01:00

YMMV,

~ Malcolm

> 
> I am not sure how easy it is to implement, but let us assume it is doable.
> What should this do:
> 
> echo 2023-10-29T23:59:59+01:00 |
>   parallel --match '(....)-(..)-(..)T(..):(..):(..)[-+](..:..)' \
>     echo {}
> 
> Multiple input sources:
> 
> parallel --match '(.)-(..)' echo {} {1}/{2}/{3}/{4} ::: A-BB C-DD ::: E-FF 
> G-HH
> 
> What happens if input data does not match:
> 
> parallel --match '(.)-(..)' echo {} {1}/{2}/{3}/{4} ::: A-BB C-DD ::: -FF 
> GG-HH
> 
> Different formats for different input sources:
> 
> parallel --match '(.)-(..)' --match '(..)-(.)' \
>   echo {} {1}/{2}/{3}/{4} ::: A-BB C-DD ::: EE-F GG-H
> 
> Can I access E-FF? (which used to be {2})
> 
> parallel --match '(.)-(..)' \
>   echo {2-orig?} {1}/{2}/{3}/{4} ::: A-BB C-DD ::: E-FF G-HH
> 
> Or must I make a match group for the original {2}?
> 
> parallel --match '((.)-(..))' \
>   echo {4} {2}/{3}/{6}/{7} ::: A-BB C-DD ::: E-FF G-HH
> 
> Is there an easy way to go from:
> 
> parallel echo {2} {1} ::: A-BB C-DD ::: E-FF G-HH
> 
> to this (where I have to calculate what number {4} would get):
> 
> parallel --match '((.)-(..))' \
>   echo {4} {1} {3} ::: A-BB C-DD ::: E-FF G-HH
> 
> Maybe matched vars should not be called {4} but {m4}; so {2} can keep its
> meaning?
> 
> 
> /Ole