error parsing regexp: invalid named capture

[anthonyfok]

Hello,

I was trying to use GitHub CLI (gh)and its --jq flag (hence gojq) to simplify the command calls a bit, i.e. to do away with the need to piping gh output to jq. However, I ran into error parsing regexp: invalid named capture sometimes. For example, the following works with piping to jq:

$ gh api repos/OpenDRR/earthquake-scenarios/contents/FINISHED \
     | jq -r '.[].name | scan(".*s_shakemap_.*(?<!MMI)\\.csv")'`
s_shakemap_ACM4p9_GeorgiaStraitFault_1.csv
s_shakemap_ACM4p9_VedderFault_196.csv
...
s_shakemap_SIM9p0_CascadiaInterfaceBestFault_11.csv

but failed with --jq flag:

$ gh api repos/OpenDRR/earthquake-scenarios/contents/FINISHED \
     --jq '.[].name | scan(".*s_shakemap_.*(?<!MMI)\\.csv")'
invalid regular expression ".*s_shakemap_.*(?P<!MMI)\\.csv": error parsing regexp: invalid named capture: `(?P<!MMI)\.csv`

and likewise when piping to the gojq:

$ gh api repos/OpenDRR/earthquake-scenarios/contents/FINISHED \
     | gojq -r '.[].name | scan(".*s_shakemap_.*(?<!MMI)\\.csv")'
gojq: invalid regular expression ".*s_shakemap_.*(?P<!MMI)\\.csv": error parsing regexp: invalid named capture: `(?P<!MMI)\.csv`

Tested with gojq v0.12.11, v0.12.13, and latest commit 2cc65b621eba3357cad1b2d6d93f53ede6c13e27 dated 2024-03-30 (post v0.12.14).

Many thanks!

Anthony

[itchyny]

This is not supported, because gojq is written in Go, and regular expression engine is RE2, which does not support lookbehind and lookahead. See WhyRE2, and its Syntax.

[anthonyfok]

I see! Thank you so much for your explanation!

Edit: For comparison, jq uses the Oniguruma (鬼車) regular expression library (https://github.com/kkos/oniguruma)