Your input is needed: Use regexp to match content

[Ole Tange]

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

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}'

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}

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