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use proc_macro2::Ident;
use std::cmp::Ordering;
#[derive(PartialEq, Eq)]
pub struct Path {
pub segments: Vec<Ident>,
}
impl PartialOrd for Path {
fn partial_cmp(&self, other: &Path) -> Option<Ordering> {
Some(self.cmp(other))
}
}
impl Ord for Path {
fn cmp(&self, other: &Path) -> Ordering {
// Lexicographic ordering across path segments.
for (lhs, rhs) in self.segments.iter().zip(&other.segments) {
match cmp(&lhs.to_string(), &rhs.to_string()) {
Ordering::Equal => {}
non_eq => return non_eq,
}
}
self.segments.len().cmp(&other.segments.len())
}
}
// TODO: more intelligent comparison
// for example to handle numeric cases like E9 < E10.
fn cmp(lhs: &str, rhs: &str) -> Ordering {
// Sort `_` last.
match (lhs == "_", rhs == "_") {
(true, true) => return Ordering::Equal,
(true, false) => return Ordering::Greater,
(false, true) => return Ordering::Less,
(false, false) => {}
}
let lhs = lhs.to_ascii_lowercase();
let rhs = rhs.to_ascii_lowercase();
// For now: asciibetical ordering.
lhs.cmp(&rhs)
}
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