Feature idea: "context matches"

[quodlibetor]

I "often" find myself doing something like:

$ rg -A5 something | grep -B5 something-else

it would be kind of awesome if rg took a --context-matches regex (that requires one of the other context specifiers (-A -B -C)) that does this automatically for me.

$ rg -A5 -B2 --context-matches 'some.regex' 'main.search'
...

$ rg --context-matches 'some.regex' 'main.search'
error: --context-matches requires one of --before, --after, or --context

[BurntSushi]

I'm not against this on principle, but it would be a very difficult feature to add in the current implementation.

[quodlibetor]

Ah, that makes sense. I was hoping that it would be as simple as just caching the output for each chunk for a bit and running a regex over that cached chunk.

[quodlibetor]

Which is obviously less efficient than some kind of fancy one-pass analysis.

[timotheecour]

related to: #360

[BurntSushi]

I was hoping that it would be as simple as just caching the output for each chunk for a bit and running a regex over that cached chunk.

The current implementation already does that. It has to, because it doesn't know which lines to print until a match occurs.

You're welcome to go look at the code and marvel at just how hard an addition like this would be. The context handling is complicated, which is why I've tagged this with libripgrep. Namely, we should think about this use case while refactoring the search code into a reusable library.

[Hywan]

Hello,

It might sound stupid, but what would be the difference between:

$ rg --context-matches 'foo' 'bar'

and:

$ rg 'foo.*bar'

[BurntSushi]

ripgrep doesn't do multiline search.

…

On Mar 3, 2017 3:29 AM, "Ivan Enderlin" ***@***.***> wrote: Hello, It might sound stupid, but what would be the difference between: $ rg --context-matches 'foo' 'bar' and: $ rg 'foo.*bar' — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#346 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAb34laVxe-2mr2JkmfV74h-QJmsWW2iks5rh893gaJpZM4L1XYf> .

[BurntSushi]

I'm going to close this not only because the implementation complexity of this scares me a little, but it opens the door to a whole new world of feature bloat that I'd rather avoid. I'd kindly suggest that if someone wants a search this sophisticated, they should just write some code or figure out a clever work-around using the existing context flags. :-)

[jdtsmith]

A related idea that might be much easier to implement: a context state match. Rather than printing lines before or after the match, a context match would print the most recent matching line of context, if any. Any given context match is only printed (once) when the main match hits. So with a file like:

* foo
** bar
*** baz
something
*boo
something else

and rg --context-match '^\*+' something would produce:

*** baz
something
* boo
something else