ctjs

Execute JavaScript at compile time to generate Rust code. Both evaluating expressions and custom derives are supported.

eval

```rust use ctjs::eval;

const X: f64 = eval! { // This is JavaScript const x = 5; String(x * Math.PI) };

assert!(X > 15.0); assert!(X < 16.0); ```

Custom Derive

```rust use ctjs::JsMacro;

[derive(Debug, JsMacro)]

[jsmacro = "fruitderive"]

enum Fruit { #[js(name = "granny smith")] Apple, Orange, Pear, }

fruitderive! { js!( let output = "const _: () = {\n"; output += "use std::fmt::{self, Write};\n"; // name is "Fruit" output += "impl fmt::Display for " + name + "{\n"; output += "fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {\n"; output += "write!(f, \"{}\", match self {\n"; // ident is "Apple" or "Orange" or "Pear" for (const { ident, attrs } of item.variants) { let string = '"' + ident.toLowerCase() + '"'; const kv = ctjs.parseattrs(attrs); if (kv.name) { string = kv.name; }

        output += "Self::" + ident + " => " + string + ",\n";
    }
    output += "})\n";
    output += "}\n}\n};\n";
    output
)

}

let fruits = vec![Fruit::Apple, Fruit::Orange, Fruit::Pear]; for fruit in &fruits { println!("Debug: {:?}, Display: {}", fruit, fruit); }

asserteq!(&fruits[0].tostring(), "granny smith"); asserteq!(&fruits[1].tostring(), "orange"); asserteq!(&fruits[2].tostring(), "pear"); ```

Current version: 0.0.1

Prior Work

• https://github.com/fusion-engineering/inline-python
  • https://docs.rs/ct-python/0.5.1/ct_python/
• https://docs.rs/embedjs/0.1.4/embedjs/

All code licensed as MIT