replace groups in regex loop

Question

I have these 2 lines:

What is P(output1|cause1=2, cause2=2)
What is P(output2|cause3=2)

I would like to change it to:

method_to_use(model, {"cause1": 2, "cause2": 2}, "output1")
method_to_use(model, {"cause3": 2}, "output2")

this is my regex:

.*P[(]([a-z1-9]+)[|](([a-z1-9]+)=([1-9]),?)+[)]

and I try to replace it like this:

method_to_use(model, {"$3": $4}, "$1")

but I only get the last fit of the group:

method_to_use(model, {"cause2": 2}, "output1")

is it possible to do some kind of a "loop" and change all fits on the way?

Answer 1

You could match the string with the following regular expression.

^.*P\(([^|]+)\|([^=]+)=(\d+)(?:, +([^=]+)=(\d+))?\)$

If capture group 4 is non-empty replace the (whole-string) match with

method_to_use(model, {"$2": $3, "$4": $5}, "$1")

This causes the string

What is P(output1|cause1=2, cause2=2)

to be replaced with

method_to_use(model, {"cause1": 2, "cause2": 2}, "output1") 

Demo 1

If capture group 4 is empty replace the match with

method_to_use(model, {"$2": $3}, "$1")

This causes the string

What is P(output2|cause3=2)

to be replaced with

method_to_use(model, {"cause3": 2}, "output2")

Demo 2

Note that the regular expressions at the two links are equivalent, the only difference is that at Demo 1 I expressed the regex in free-spacing mode, which permits it to be self-documenting.

Instead of replacing the entire string one could of course simply form the new string from the values of the capture groups. If that is done ^.*P at the beginning of the regex could be changed to simply P.

The regex engine performs the following operations.

^             # match beginning of line
.*P\(         # match 0+ chars then '|('      
([^|]+)       # save 1+ chars except '|' in cap grp 1 (output)    
\|            # match ':'
([^=]+)       # save 1+ chars except '=' in cap grp 2 (causeA)
=             # match '='
(\d+)         # save 1+ digits in cap grp 3 (causeAval)
(?:           # begin non-cap grp
  ,\ +        # match ',' then 1+ spaces
  ([^=]+)     # match 1+ chars except '=' in cap grp 4 (causeB)   
  =           # match '='
  (\d+)       # match 1+ digits in cap grp 5 (causeBval)
)?            # end non-cap grp and make it optional  
\)            # match ')'
$             # match end of line