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// Copyright 2024 Gabriel Bjørnager Jensen.
//
// This file is part of bZipper.
//
// bZipper is free software: you can redistribute
// it and/or modify it under the terms of the GNU
// Lesser General Public License as published by
// the Free Software Foundation, either version 3
// of the License, or (at your option) any later
// version.
//
// bZipper is distributed in the hope that it will
// be useful, but WITHOUT ANY WARRANTY; without
// even the implied warranty of MERCHANTABILITY or
// FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Less-
// er General Public License along with bZipper. If
// not, see <https://www.gnu.org/licenses/>.
use crate::Discriminant;
use std::borrow::Borrow;
use syn::Variant;
pub struct DiscriminantIter<I: IntoIterator<Item: Borrow<Variant>>> {
variants: I::IntoIter,
prev: Option<Discriminant>,
}
impl<I: IntoIterator<Item: Borrow<Variant>>> DiscriminantIter<I> {
#[inline(always)]
#[must_use]
pub fn new(variants: I) -> Self {
Self {
variants: variants.into_iter(),
prev: None,
}
}
}
impl<I: IntoIterator<Item: Borrow<Variant>>> Iterator for DiscriminantIter<I> {
type Item = (Discriminant, I::Item);
#[inline]
fn next(&mut self) -> Option<Self::Item> {
let variant = self.variants.next()?;
let discriminant = if let Some((_, ref discriminant)) = variant.borrow().discriminant {
Discriminant::parse(discriminant)
} else if let Some(discriminant) = self.prev {
let value = discriminant.0
.checked_add(0x1)
.unwrap_or_else(|| panic!("overflow following discriminant `{discriminant:?}`"));
Discriminant(value)
} else {
Default::default()
};
self.prev = Some(discriminant);
Some((discriminant, variant))
}
#[inline(always)]
fn size_hint(&self) -> (usize, Option<usize>) {
self.variants.size_hint()
}
}
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