adhoc_derive  

Experimental: Derive FromStr impl based on regex provided via attribute

Usage

Add the following in your Cargo.toml:

[dependencies]
adhoc_derive = "0.1.1"
lazy_static = "1.2.0"
regex = "1.1.0"

Then, you can derive a std::str::FromStr impl as follows:

use adhoc_derive::FromStr;

#[derive(FromStr)]
#[adhoc(regex = r"^#(?P<id>\d+) @ (?P<x>\d+),(?P<y>\d+): (?P<width>\d+)x(?P<height>\d+)$")]
struct Rectangle {
    id: usize,
    x: usize,
    y: usize,
    width: usize,
    height: usize,
}

let rect: Rectangle = "#123 @ 3,2: 5x4".parse().unwrap();
assert_eq!(123, rect.id);
assert_eq!(3, rect.x);
assert_eq!(2, rect.y);
assert_eq!(5, rect.width);
assert_eq!(4, rect.height);

In general, each field of the struct needs to implement std::str::FromStr and each field identifier needs to correspond to a named capture group in the regex.

For a more comprehensive guide, refer to GUIDE.md

Limitations

This crate is experimental and has a lot of rough edges. In no particular order:

• Only works on structs with named fields (i.e no enums, tuple structs, etc.)
• Doesn't work with generic structs out of the box (it should work if you add the required trait bounds yourself)
• Not yet implemented: optional patterns, i.e. (...)? => Option<...>
• Not yet implemented: repeating patterns, i.e. (...)* => Vec<...>
• Error handling and especially reporting is basically non-existent
• Provided regex is not validated at compile-time