partial-cmp-derive 0.3.1

Derive PartialEq, Eq, PartialOrd, Ord, and Hash with fine-grained control over field comparison
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29

use darling::FromVariant;
use darling::ast::Fields;
use darling::util::SpannedValue;
use syn::Ident;

use crate::types::OrdField;

/// Variant-level attributes for enums.
#[derive(Debug, Clone, FromVariant)]
#[darling(attributes(ord))]
pub struct OrdVariant {
    /// The variant identifier.
    pub ident: Ident,

    /// The variant's fields.
    pub fields: Fields<OrdField>,

    /// Explicit rank for this variant (lower = less than).
    #[darling(default)]
    pub rank: Option<SpannedValue<i32>>,
}

impl OrdVariant {
    /// Returns the effective rank for sorting variants.
    /// If an explicit rank is set, use it; otherwise use the declaration index.
    pub fn effective_rank(&self, declaration_index: usize) -> i32 {
        self.rank.as_ref().map_or(declaration_index as i32, |r| **r)
    }
}