qemit

qemit is a minimalist quasi-quoting library for Rust. It provides a lightweight, declarative macro-based alternative to the quote crate, designed specifically for procedural macros or code generation tasks where a small dependency footprint is preferred.

qemit! {
    fn hello() { ~world }
}

Features

Small Footprint: Minimal dependencies (only proc_macro2).
Standard Syntax: Uses the familiar ~variable syntax for interpolation.
Recursive Groups: Automatically handles nested braces {}, parentheses (), and brackets [].
Declarative: Built entirely with macro_rules!, avoiding the need for a procedural macro to power the quoting itself.

Installation

Add qemit to your Cargo.toml:

[dependencies]
qemit = "0.1.0"

Usage

The primary entry point is the qemit! macro. It returns a proc_macro2::TokenStream.

Basic Quoting

use qemit::qemit;

let tokens = qemit! {
    fn hello_world() {
        println!("Hello from qemit!");
    }
};

Interpolation

Use the ~ operator to inject variables that implement the ToTokens trait.

use qemit::qemit;
use proc_macro2::{Ident, Span};

let fn_name = Ident::new("dynamic_function", Span::call_site());
let body = qemit! { println!("Inside the function"); };

let tokens = qemit! {
    fn ~fn_name() {
        ~body
    }
};

Nested Interpolation

qemit correctly recurses into groups, allowing you to interpolate values deep within blocks or expressions:

let value = proc_macro2::Literal::i32_unsuffixed(42);

let tokens = qemit! {
    {
        {
            let x = ~value;
        }
    }
};

How it Works

Unlike traditional quasi-quoting libraries that use procedural macros to parse their own input, qemit uses a sliding window technique in declarative macros. It processes tokens by looking at a context of surrounding tokens to identify the ~ operator and its target.

This makes it extremely fast to compile and suitable for projects where adding a heavy build-dependency tree is undesirable.

Trait: `ToTokens`

To make a custom type compatible with qemit!, implement the ToTokens trait:

impl qemit::ToTokens for MyType {
    fn to_tokens(&self, tokens: &mut qemit::proc_macro2::TokenStream) {
        // Append your tokens here
    }
}

License

This project is dually licensed under:

Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
MIT License (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Cheers, RazkarStudio.

qemit 0.1.0