How to Show Line-Excerpt Near the Match?

[johnyradio]

version

% rg --version ripgrep 11.0.2 -SIMD -AVX (compiled) +SIMD -AVX (runtime)

install ripgrep?

pacman -S ripgrep

operating system

% hostnamectl Operating System: Arch Linux Kernel: Linux 5.2.8-arch1-1-ARCH Architecture: x86-64

question

On very long lines, how can i return a limited number of characters before and after the match? --max-columns-preview seems to preview the beginning of the line, which may not contain the match, so that's less useful.

i hoped combining -o with --max-columns-preview might give the desired result. Maybe that's a feature request?

thx!

[BurntSushi]

On very long lines, how can i return a limited number of characters before and after the match?

You can't.

Maybe that's a feature request?

Could you please provide a more complex specification for how this feature is supposed to work? If it helps, write it as if you were adding documentation for the new feature to the man page.

[johnyradio]

Use -o with --max-columns-preview to display the matching text in context. 

If the original text is:

Every year since 1938, the organization presents Stern Grove Festival, a free concert series, in Sigmund Stern Grove, a beautiful outdoor amphitheater located at 19th Avenue and Sloat Boulevard in San Francisco.

Then this rg  -o -M 10 --max-columns-preview Grove

will return und Stern Grove, a beauti

There might be more correct options than how i've done , but this shows the basic idea. 

[BurntSushi]

Thanks, but that's not good enough. -o -M10 --max-columns-preview already has a defined behavior.

I don't see a way to do this without an additional flag.

[borekb]

I'd also love this feature (minified JS in my case...), it's probably true that it cannot be done without an additional flag. I imagine having something like this in my .ripgreprc:

--max-columns=150
--max-columns-preview
--max-columns-preview-type=contextual

This hypothetical --max-columns-preview-type option would support two values:

• beginning-of-line (current behavior)
• contextual

[rod-stuchi]

This would be a really wanted feature, like borekb said to look in minified JS files.

I think this is like Context, flags -A, -B and -C but instead of lines, will be applied in columns.

New flags (like context in lines) should be the way to go, imho.

[BurntSushi]

Plus-1 comments aren't going to move this forward. A specification, as requested above, would be more helpful.

[rod-stuchi]

ok fair, maybe this would help? Like a documentation for the new feature in man rg?

--after-context-column NUM
           Show NUM columns after each match in one line.

           This overrides the --context-column flag.

-- context-column NUM
           Show NUM columns before and after each match in one line. This is equivalent to providing both the
           --before-context-column and --after-context-column flags with the same value.

           This overrides both the -before-context-column and --after-context-column.

--before-context-column
           Show NUM columns before each match in one line.

           This overrides the --context-column flag.

As an example, please consider this piece of text:

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Pellentesque vel hendrerit est, vel interdum turpis. Proin pharetra nulla eu nulla aliquet, nec consequat felis bibendum. Vestibulum augue odio, eleifend non pellentesque ac, dapibus in urna. Donec at vehicula risus. Nullam consectetur vitae felis mollis fringilla. Ut tincidunt magna in enim tincidunt lacinia. Orci varius natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. Cras lectus dui, ullamcorper accumsan consectetur sed, porta sed justo. Etiam massa est, ornare commodo porttitor ut, bibendum quis mauris. Etiam eget laoreet ante. Fusce molestie leo vitae dolor dignissim gravida.

running

rg --context-column 5 dolor

will return something like:

1: psum dolor sit 1: itae dolor dign

[kkocdko]

Here's an workaround, according to this comment:

rgnc(){ rg -p --colors match:none -o ".{0,50}$1.{0,50}" | rg -C 9 "$1" ;}
rgnc "=require\("

But overlapping problem still exists. --pcre2 and look-ahead maybe helpful.

And a more magical maybe with awk if anyone want, LOL.

~/misc/apps/mold -run cargo run -- --color always --vimgrep '_OMG_' | awk '{
    split($0,f,":");
    sub(/^([^:]+:)/,"",$0);
    sub(/^([^:]+:)/,"",$0);
    sub(/^([^:]+:)/,"",$0);
    print f[1]":"f[2]":"f[3]":"substr($0, substr(f[3], 5) - 2, 50);
}'

[kkocdko]

My advice is to implement the --max-columns-preview-before 10 to make --max-columns-preview starts printing from "10 chars before first match". Then we can use the existing config.per_match to output one line per match.

This simplifies the implementation a lot, and it's still acceptable for most use cases. @BurntSushi what you think about this design? If you agree, I'll continue to implement the #2683 , update docs and tests.

However I found that config.per_match field is not exposed directly to cli args, only when --vimgrep. Let's consider making a change to it?

https://github.com/BurntSushi/ripgrep/blob/56c7ad175ac1326e8d36a880061ca3b0e67ad5ea/crates/core/flags/hiargs.rs#L615-L617

[ssendev]

I came here to request the same feature also dealing with minified js and imagined it working like https://github.com/BurntSushi/ripgrep/issues/1352#issuecomment-646379743 described

Here is an improved interim solution which seems pretty usable

rgnc(){ Q="$1"; shift; rg --pretty --colors match:none -o ".{0,50}$Q.{0,50}" "$@" | rg --passthru "$Q" ;}