re2c VS ninja

(1) Zulip Chat - https://zulip.com/ - seems to be reasonably popular, but more people should know about it

I’ve been using it for over 5 years now [1], and it’s as good as ever. It’s way faster than any other chat app I’ve used. It has a good UI and conversation model. It has a simple and functional API that lets me curl threads and write blog posts based on them.

(only problem is that I Ctrl-+ in my browser to make the font bigger – I think it’s too dense for most people)

(2) re2c regex to state machine compiler - https://re2c.org

A gem from the 90’s, which people have done a great job maintaining and improving (getting Go and Rust target support in the last few years). I started using it in 2016, and used for a new program a few months ago. I came to the conclusion that it should have been built into C, because C has shitty string processing – and Ken Thompson both invented C AND brought regular languages to computing !!

In comparison, treesitter lexers are very low level, fiddly, and error prone. I recently saw dozens of ad hoc fixes to the tree-sitter-bash lexer, which is unsurprising if you look at the structure of the code (manually crawling through backslashes and braces in C).

https://github.com/tree-sitter/tree-sitter-bash/blob/master/...

These fixes are definitely appreciated, but I think it indicates a problem with the model itself.

(based on https://lobste.rs/s/endspx/software_you_are_thankful_for#c_y...)

[1] https://www.oilshell.org/blog/2018/04/26.html

The "Papers" section on re2c's web site continues Laurikari's work: http://re2c.org/

... but I haven't found them particularly accessible. And it's not clear it's a viable strategy in a general purpose regex engine. Namely, I'm not sure how much bigger it makes the DFA.

Also, AFAIK, these are DFAs. They are different theoretical structures with explicitly more power.

> and then an NDFA is used to match a third time, to extract the capture groups.

That's the PikeVM. It's an NFA simulation. Although it uses additional storage and is otherwise more computationally powerful than just a plain NFA.

> What do you gain by using it?

Performance, although this possibly depends on your compiler, whether you use PGO, and similar finicky issues.

Example: https://eli.thegreenplace.net/2012/07/12/computed-goto-for-e...

Some prior HN discussion: https://news.ycombinator.com/item?id=18678920

Another example where goto is relevant is implementing finite automata. A (very short) paper from 1988 that discusses three different ways of implementing a finite state machine is "How (Not) to Code a Finite State Machine". The documentation of RE2C may be even more interesting: https://re2c.org

RE2C is a program that compiles finite automata into C, Go, or Rust code. It provides many implementation strategies: it can make use of computed or labelled gotos when the language provides them.

Implementing pushdown automata comes with similar issues.

wget https://github.com/skvadrik/re2c/releases/download/1.0.3/re2c-1.0.3.tar.gz tar -zxvf re2c-1.0.3.tar.gz cd re2c-1.0.3/ ./configure make make install

In Rust I use https://docs.rs/logos/latest/logos/. I think another similar is http://re2c.org

re2c is an open-source lexer generator. It uses regular expressions to recognize tokens.

Those suggested crates are still more or less the popular options. There was also recently added support for Rust in re2c.

First, the implementation of strtotime is a textbook study in why other people's C code is not where you want to spend time. You can see the guts of the implementation logic here. This isn't stock C code -- it's code for a system called re2c. This system allows you to write regular expressions in a custom DSL (domain specific language), and then transform/compile those regular expressions down to C programs (also C++ and Go) that will execute those regular expressions. Something in PHP's make file uses this parse_date.re file to generate parse_date.c. If you don't realize parse_date.c is a generated file, this can be extremely rough going. If you've not familiar with re2c is can be regular rough going. We leave further exploration as an exercise for the reader -- an exercise we haven't taken ourself.

Under the hood, Rescript uses a build system called Ninja. Ninja is similar to Make, but cross-platform and more minimal/performant.

Really? I thought most new projects were switching to ninja[^1] and have never used it.

[^1]: https://ninja-build.org/

warning: Starting with the September 2023 release, the default triplet for vcpkg libraries will change from x86-windows to the detected host triplet (x64-windows). To resolve this message, add --triplet x86-windows to keep the same behavior. Computing installation plan... The following packages will be built and installed: * egl-registry:x86-windows -> 2022-09-20 glew:x86-windows -> 2.2.0#3 * opengl:x86-windows -> 2022-12-04#3 * opengl-registry:x86-windows -> 2022-09-29#1 * vcpkg-cmake:x64-windows -> 2023-05-04 * vcpkg-cmake-config:x64-windows -> 2022-02-06#1 Additional packages (*) will be modified to complete this operation. Detecting compiler hash for triplet x86-windows... A suitable version of powershell-core was not found (required v7.2.11) Downloading portable powershell-core 7.2.11... Downloading powershell-core... https://github.com/PowerShell/PowerShell/releases/download/v7.2.11/PowerShell-7.2.11-win-x86.zip->C:\vcpkg\downloads\PowerShell-7.2.11-win-x86.zip Downloading https://github.com/PowerShell/PowerShell/releases/download/v7.2.11/PowerShell-7.2.11-win-x86.zip Extracting powershell-core... error: while detecting compiler information: The log file content at "C:\vcpkg\buildtrees\detect_compiler\stdout-x86-windows.log" is: -- Downloading https://github.com/ninja-build/ninja/releases/download/v1.10.2/ninja-win.zip -> ninja-win-1.10.2.zip... -- Configuring x86-windows CMake Error at scripts/cmake/vcpkg_execute_required_process.cmake:112 (message): Command failed: C:/vcpkg/downloads/tools/ninja/1.10.2-windows/ninja.exe -v Working Directory: C:/vcpkg/buildtrees/detect_compiler/x86-windows-rel/vcpkg-parallel-configure Error code: 1 See logs for more information: C:\vcpkg\buildtrees\detect_compiler\config-x86-windows-rel-CMakeCache.txt.log C:\vcpkg\buildtrees\detect_compiler\config-x86-windows-out.log

I thought I would share my custom installer script for the latest GitHub versions of CMake, Ninja, and Meson.

Now that you have your build system all generated you can go ahead and build everything. By default Meson will use Ninja as the build tool. Ninja is similar to Make but much much faster. You can also generate additional build systems but that's outside of the scope of this post.

There are also some other tools like https://ninja-build.org/ that you might prefer using instead

I got Ninja from https://github.com/ninja-build/ninja, latest release. I'm assuming this is a false positive?

Oh excellent, then better (and more portable!) tools are available:

http://pants.build

https://ninja-build.org

https://buck.build

and, if you hate yourself: https://bazel.build