Derive Macro AtomSet 

#[derive(AtomSet)]
{
    // Attributes available to this derive:
    #[default]
    #[atom]
}

Derives an efficient AtomSet implementation for interned CSS identifiers.

This proc macro automatically generates optimized string-to-enum matching code.

Variant Attributes

• #[default]: Marks this variant as the empty/fallback value (returns empty string)
• #[atom("custom")]: Overrides the default string representation

Naming Convention

If #[atom("")] is not provided a string is derived from the variant name:

• Px → "px"
• FontSize → "font-size"
• WebkitTransform → "webkit-transform"

Example

// Provide this trait definition:
trait AtomSet {
    fn from_str(keyword: &str) -> Self;
    fn to_str(self) -> &'static str;
    fn len(&self) -> u32;
    fn from_bits(bits: u32) -> Self;
    fn as_bits(&self) -> u32;
}
use derive_atom_set::AtomSet;

#[derive(Debug, Default, Copy, Clone, PartialEq, AtomSet)]
pub enum MyAtomSet {
    #[default]
    Unknown, // Must provide an empty default!

    // Absolute units
    Px, Pt, Pc, In, Cm, Mm, Q,

    // Relative units
    Em, Ex, Ch, Rem, Lh,

    // Viewport units
    Vw, Vh, Vi, Vb, Vmin, Vmax,

    // Container query units
    Cqw, Cqh, Cqi, Cqb, Cqmin, Cqmax,

    // Special case
    #[atom("%")]
    Percent,
}

// Usage:
assert_eq!(MyAtomSet::from_str("px"), MyAtomSet::Px);
assert_eq!(MyAtomSet::from_str("PX"), MyAtomSet::Px);  // Case insensitive matches
assert_eq!(MyAtomSet::Px.to_str(), "px");
assert_eq!(MyAtomSet::Percent.to_str(), "%");
assert_eq!(MyAtomSet::from_str("unknown"), MyAtomSet::Unknown);