primes-cpp VS astexplorer

Everybody mentions this, and what's great is that it is a pretty natural solution to a lot of problems. I remember coming up with a version of it while writing an optimized prime-sieve[1], and was surprised when I later learned that it was some named technique.

In addition to just the basic loop-unrolling (which I'm pretty sure you usually don't need to do by hand with modern compilers), it works really well when you need to jump into the middle of a pattern. Like if you're sieving primes in a wheel-factorized array.

[1] https://github.com/patricksjackson/primes-cpp/blob/master/pr...

  // Here we're only checking possible primes after wheel-factorization

You can play with your code here, and visualise ASTs for the same.

Website

To understand this syntax, I recommend exploring AST Explorer. You will have a better view of how the AST of JavaScript works and how to correlate it with the Eslint syntaxy:

You can never mistake type_declaration with an identifier, otherwise the program will not work. Aside from that constraint, you are free to name them whatever you like, there is no one standard, and each parser has it own naming conventions, unless you are planning to use something like LLVM. If you are interested, you can see examples of naming in different language parsers in the AST Explorer.

The rule that I want to write will be called not-allows-underscore: the idea is to abolish the use of underscores when declaring variables or functions. It's a real dummy rule, but it should be enough to see in action the concepts that we have discussed earlier. The first thing that I would do is to go to AST Explorer, write down a code that declares variables and functions (both standard and arrows one) and take a look at what type of node is the one that encodes the identifier. Doing that, I found out that the node type of my interest is Identifier, what a surprise! 🤣. In particular, the structure of the node holds the string used as identifier in the name property.

All the information about the API, AST node names, AST Explorer, etc. you can read in the official documentation. I’m just going to show examples of how to automate the check-up of our created conventions.

AST Viewer

If you want to see how the AST of popular languages looks, I recommend the AST Explorer. It supports various languages, and you can view the complete AST and navigate through the nodes. If you want to go further, you can try to copy some logic from an existing parser and implement it in your own, such as calculating an expression according to precedence order, for example: 1 + 2 * 3 (which is 7, not 9).

https://astexplorer.net/ is a good resource/playground for understanding ASTs and transpilers.