pulldown-cmark VS regex

As a platform that allows expressiveness, we want our users to be bold enough to ask and answer questions with either plain text or some markdowns. Compiling markdown to HTML in Rust can be done via the pulldown-cmark crate. We used it in this utility function:

I also really like this paradigm. It’s just that in old crusty null-terminated C style this is really awkward because the input data must be copied or modified. But it’s not an issue when using slices (length and pointer). Unfortunately most of the C standard library and many operating system APIs expect that.

I’ve seen this referred to as a pull parser in a Rust library? (https://github.com/raphlinus/pulldown-cmark)

Really glad to see this! Really want an easy way to render graphs in Rust without resorting to the graphiz binary.

What is the current status? Not seeing it listed anywhere, like if there are features that are not supported or if it uses certain layout algorithms but others are desired.

Would you be willing to make a `[lib]` available? I see you have a `lib.rs` but it'd be great if using it didn't require pulling in `[[bin]]` dependencies (you can mark them as optional and mark `required-features` on your bin like pulldown-cmark does [0] or split it into a separate crate in a workspace). It'd also be good to find an available name for the lib and get it published (looks like someone might be squatting on `layout`).

[0] https://github.com/raphlinus/pulldown-cmark/blob/master/Carg...

Author here. I actually was not aware of cmark.ex - thanks for pointing it out.

In this case the code reuse was more important than pure native speed. We already had a Rust library that used pulldown-cmark [1] with some custom tweaks that we wanted to duplicate. Maybe this behavior could have been copied using cmark.ex too (we thought about doing this in pure Elixir, as mentioned in the post), but given how straightforward Rustler made integrating our existing code, this seems like the better choice.

[1] https://github.com/raphlinus/pulldown-cmark

It turned out that making the most popular Elixir Markdown processor, Earmark (originally written by Dave Thomas) and pulldown-cmark, a Rust Markdown processor, produce the same output was going to be difficult. We also required some customization that was not available in both libraries.

The crate that's closest to production quality code is pulldown-cmark, but I don't hold it up as an example of well-written code, because it's not particularly easy to understand and there's a lot of very low level code to consume the CommonMark syntax - that helps with code bloat and compile time, but not clarity.

The Markdown processor is pulldown-cmark, which supports these extensions:

The homepage has a benchmark that compares Zed's "insertion latency" to other editors, and this is the description:

> Open input.rs at the end of line 21 in rust-lang/regex. Type z 10 times, measure how long it takes for each z to display since hitting the z key.

Could someone clarify what that means? My interpretation of that was to go to https://github.com/rust-lang/regex/blob/master/regex-cli/arg... and start typing 'z' at the end of line 21, but that doesn't seem to make any sense. I guess that repo got refactored and those instructions are out of date?

We also used the avenue to sluggify the question title. We used regex to fish out and replace all occurrences of punctuation and symbol characters with an empty string and using the itertools crate, we joined the words back together into a single string, where each word is separated by a hyphen ("-").

Command-Line Rust taught me how to use crates like clap, assert_cmd, and regex. I felt lost before because I didn't know about Rust's ecosystem--which is arguably as important as the language itself. Also, looking up and comparing libraries is a tiring task! blessed.rs is nice but Command-Line Rust really saved me from analysis paralysis.

burntsushi actually regrets making regex replace return a Cow: https://github.com/rust-lang/regex/issues/676#issuecomment-6.... I’m glad it does, and wish it took an impl Into> there, for the reasons discussed in the issue, but burntsushi has a lot more experience of the practical outcomes of this. Just something more to think about.

I'm not familiar with the AoC problem. You might be able to. But RegexSet doesn't give you match offsets.

You can drop down to regex-automata, which does let you do multi-regex search and it will tell you which patterns match[1]. The docs have an example of a simple lexer[2]. But... that will only give you non-overlapping matches.

You can drop down to an even lower level of abstraction and get multi-pattern overlapping matches[3], but it's awkward. The comment there explains that I had initially tried to provide a higher level API for it, but was unsure of what the semantics should be. Getting the starting position in particular is a bit of a wrinkle.

[1]: https://docs.rs/regex-automata/latest/regex_automata/meta/in...

[2]: https://docs.rs/regex-automata/latest/regex_automata/meta/st...

[3]: https://github.com/rust-lang/regex/blob/837fd85e79fac2a4ea64...

It’s not quite that simple, but folks are working on it.

https://github.com/rust-lang/regex/issues/425#issuecomment-1...

https://github.com/helix-editor/helix/pull/211#issuecomment-...

Dependencies used: - regex - unicode_reader - rust decimal - tokio

https://www.cs.princeton.edu/courses/archive/fall19/cos226/l... and https://kean.blog/post/lets-build-regex are excellent introductions to implementing a (very) simplified regex engine: construct a nondetermistic finite state automaton for the regex, then perform a graph search on the resulting digraph; if the vertex corresponding to your end state is reachable, you have a match.

I think this exercise is valuable for anyone writing regexes to not only understand that there's less magic than one might think, but also to visualize a bunch of balls bouncing along an NFA - that bug you inevitably hit in production due to catastrophic backtracking now takes on a physical meaning!

Separately re: the OP, https://github.com/rust-lang/regex/issues/822 (and specifically BurntSushi's comment at the very end of the issue) adds really useful context to the paragraph in the OP about niche APIs: https://blog.burntsushi.net/regex-internals/#problem-request... - searching with multiple regexes simultaneously against a text is both incredibly complex and incredibly useful, and I can't wait to see what the community comes up with for this pattern!