Proc_macro NPM

proc_macro.js

proc_macro.js is a JavaScript/TypeScript implementation of Rust procedural macros 🔥. The goal of this project is to combine the ideas from syn, quote, proc_macro, and proc_macro2 in one comprehensive parsing package.

Unlike sweet.js, the goal is to write hygenic/unhygenic macros that require only vanilla JavaScript. This comes with the caveat of JIT and tagged templates.

You can find more information on the package website.

Please note that this project is still in development. Feel free to report any bugs on GitHub!

Installing

npm install --save proc_macro

Sample using ES6

Parsing bee number system 🐝 where the number of e in bee... gives the number value. For example be b bee beeee = 1024.

import { Expression, TokenStream, End, Ident, proc_macro, quote } from "proc_macro";

// Defining Bee parsing object by extending Expression.
class Bee extends Expression {
    count: string;

    constructor(count: string) {
        super();
        this.count = count;
    }

    // Must define the parse static method!
    public static parse(ts: TokenStream): Bee {
        let count = "";

        // Check if we reached end.
        while(!ts.peek`${End}`) {
            // If not, get next Ident.
            let [bee] = ts.parse`${Ident}`;

            // Check if the ident is bee.
            if(!/^[Bb]e*$/.test(bee.value)) 
                throw ts.error("Passed text is not bee.");

            // Check if bee fits in the number system.
            if(bee.value.length > 10) 
                throw ts.error("Bee should be smaller than 11 letters.");

            count += bee.value.length - 1;
        }

        return new Bee(count);
    }

    public toJavaScript(): string {
        // Quote tagged template makes tokenizing easier!
        return quote`${this.count.toString()}`;
    }
}

// Tempalte function to pass to proc_macro.
const beeParser = (tokenStream: TokenStream): string => {
    let bee = Bee.parse(tokenStream);
    return bee.toJavaScript();
}

// Converts the parser to tagged template.
const bee = proc_macro(beeParser);

// Parse and eval...
let b = eval(bee`be b bee beeee`);

// Should give `1024`!
console.log(b);