bumpalo
regex
bumpalo | regex | |
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16 | 91 | |
1,300 | 3,355 | |
- | 1.4% | |
7.5 | 8.9 | |
21 days ago | 13 days ago | |
Rust | Rust | |
Apache License 2.0 | Apache License 2.0 |
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bumpalo
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Rust vs Zig Benchmarks
Long story short, heap allocation is painfully slow. Any sort of malloc will always be slower than a custom pool or a bump allocator, because it has a lot more context to deal with.
Rust makes it especially hard to use custom allocators, see bumpalo for example [0]. To be fair, progress is being made in this area [1].
Theoretically one can use a "handle table" as a replacement for pools, you can find relevant discussion at [2].
[0] https://github.com/fitzgen/bumpalo
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Rust Memory Management
There are ways to accomplish this as well. Different allocator libraries exist for this kind of scenario, namely bumpallo which allocates a larger block of memory from the kernel, and allocates quickly thereafter. That would amortize the cost of memory allocations in the way I think you're after?
- Custom allocators in Rust
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A C Programmers take on Rust.
Meaning, storing a lot of things in the same block of allocated memory? Vec is a thing, you know. There's also a bump allocator library.
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Hypothetical scenario - What would be better - C, C++ or Rust? (Read desc.)
There are data structures like slotmap, and relatively low-level crates like bumpalo. This is not to say that either fits your use case, just that you definitely have access to the necessary parts to fit what you describe.
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Implementing "Drop" manually to show progress
Sometimes you can put everything in a bump allocator, then when you're done, free the entire bump allocator in one go. https://docs.rs/bumpalo/
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Any languages doing anything interesting with allocators?
This is useful with crates like bumpalo which give you bump-allocation arenas whose lifetimes are tied to the objects they allocate.
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I’m Porting the TypeScript Type Checker Tsc to Go
TSC doesn't need to "stick around", right? Just a run-once and the program is over?
In those cases, https://github.com/fitzgen/bumpalo works amazingly as an arena. You can pretty much forget about reference counting and have direct references everywhere in your graph. The disadvantage is that it's hard to modify your tree without leaving memory around.
We use it extensively in http://github.com/dioxusLabs/dioxus and don't need to worry about Rc anywhere in the graph/diffing code.
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Allocating many Boxes at once
Probably bumpalo, but then its Box will have a lifetime parameter - bumpalo::boxed::Box<'a, dyn MyTrait>
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Graydon Hoare: What's next for language design? (2017)
Strictly speaking, Rust doesn't need this as a built-in language feature, because its design allows it to be implemented as a third-party library: https://docs.rs/bumpalo
The biggest problem is that there's some awkwardness around RAII; I'm not sure whether that could have been avoided with a different approach.
Of course, ideally you'd want it to be compatible with the standard-library APIs that allocate. This is implemented, but is not yet at the point where they're sure they won't want to make backwards-incompatible changes to it, so you can only use it on nightly. https://doc.rust-lang.org/stable/std/alloc/trait.Allocator.h...
Or are you suggesting that the choice of allocator should be dynamically scoped, so that allocations that occur while the bump allocator is alive automatically use it even if they're in code that doesn't know about it? I think it's not possible for that to be memory-safe; all allocations using the bump allocator need to know about its lifetime, so that they can be sure not to outlive it, which would cause use-after-free bugs. I'm assuming that Odin just makes the programmer responsible for this, and if they get it wrong then memory corruption might occur; for a memory-safe language like Rust, that's not acceptable.
regex
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Zed is now open source
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?
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CryptoFlow: Building a secure and scalable system with Axum and SvelteKit - Part 3
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 ("-").
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Command Line Rust is a great book
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.
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Common Rust Lifetime Misconceptions
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.
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Advent of Code 2023 is nigh
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...
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Text Showdown: Gap Buffers vs. Ropes
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-...
- Please ask questions (rust-lang/regex)
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ScripterC - Rust-lang set
Dependencies used: - regex - unicode_reader - rust decimal - tokio
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Regex Engine Internals as a Library
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!
What are some alternatives?
rust-phf - Compile time static maps for Rust
re2 - modern regular expression syntax everywhere with a painless upgrade path [Moved to: https://github.com/SonOfLilit/kleenexp]
generational-arena - A safe arena allocator that allows deletion without suffering from the ABA problem by using generational indices.
node-re2 - node.js bindings for RE2: fast, safe alternative to backtracking regular expression engines.
hashbrown - Rust port of Google's SwissTable hash map
zig - General-purpose programming language and toolchain for maintaining robust, optimal, and reusable software.
moonfire-nvr - Moonfire NVR, a security camera network video recorder
ngrams - (Read-only) Generate n-grams
feel
regex-benchmark - It's just a simple regex benchmark of different programming languages.
grenad - Tools to sort, merge, write, and read immutable key-value pairs :tomato:
whatlang-rs - Natural language detection library for Rust. Try demo online: https://whatlang.org/