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use crate::def::{CtorOf, DefKind, Res};
use crate::def_id::DefId;
use crate::hir::{self, BindingAnnotation, ByRef, HirId, PatKind};
use rustc_data_structures::fx::FxHashSet;
use rustc_span::hygiene::DesugaringKind;
use rustc_span::symbol::Ident;
use rustc_span::Span;
use std::iter::{Enumerate, ExactSizeIterator};
pub struct EnumerateAndAdjust<I> {
enumerate: Enumerate<I>,
gap_pos: usize,
gap_len: usize,
}
impl<I> Iterator for EnumerateAndAdjust<I>
where
I: Iterator,
{
type Item = (usize, <I as Iterator>::Item);
fn next(&mut self) -> Option<(usize, <I as Iterator>::Item)> {
self.enumerate
.next()
.map(|(i, elem)| (if i < self.gap_pos { i } else { i + self.gap_len }, elem))
}
fn size_hint(&self) -> (usize, Option<usize>) {
self.enumerate.size_hint()
}
}
pub trait EnumerateAndAdjustIterator {
fn enumerate_and_adjust(
self,
expected_len: usize,
gap_pos: hir::DotDotPos,
) -> EnumerateAndAdjust<Self>
where
Self: Sized;
}
impl<T: ExactSizeIterator> EnumerateAndAdjustIterator for T {
fn enumerate_and_adjust(
self,
expected_len: usize,
gap_pos: hir::DotDotPos,
) -> EnumerateAndAdjust<Self>
where
Self: Sized,
{
let actual_len = self.len();
EnumerateAndAdjust {
enumerate: self.enumerate(),
gap_pos: gap_pos.as_opt_usize().unwrap_or(expected_len),
gap_len: expected_len - actual_len,
}
}
}
impl hir::Pat<'_> {
pub fn each_binding(&self, mut f: impl FnMut(hir::BindingAnnotation, HirId, Span, Ident)) {
self.walk_always(|p| {
if let PatKind::Binding(binding_mode, _, ident, _) = p.kind {
f(binding_mode, p.hir_id, p.span, ident);
}
});
}
pub fn each_binding_or_first(
&self,
f: &mut impl FnMut(hir::BindingAnnotation, HirId, Span, Ident),
) {
self.walk(|p| match &p.kind {
PatKind::Or(ps) => {
ps[0].each_binding_or_first(f);
false
}
PatKind::Binding(bm, _, ident, _) => {
f(*bm, p.hir_id, p.span, *ident);
true
}
_ => true,
})
}
pub fn simple_ident(&self) -> Option<Ident> {
match self.kind {
PatKind::Binding(BindingAnnotation(ByRef::No, _), _, ident, None) => Some(ident),
_ => None,
}
}
pub fn necessary_variants(&self) -> Vec<DefId> {
let mut variants = vec![];
self.walk(|p| match &p.kind {
PatKind::Or(_) => false,
PatKind::Path(hir::QPath::Resolved(_, path))
| PatKind::TupleStruct(hir::QPath::Resolved(_, path), ..)
| PatKind::Struct(hir::QPath::Resolved(_, path), ..) => {
if let Res::Def(DefKind::Variant | DefKind::Ctor(CtorOf::Variant, ..), id) =
path.res
{
variants.push(id);
}
true
}
_ => true,
});
let mut duplicates = FxHashSet::default();
variants.retain(|def_id| duplicates.insert(*def_id));
variants
}
pub fn contains_explicit_ref_binding(&self) -> Option<hir::Mutability> {
let mut result = None;
self.each_binding(|annotation, _, _, _| match annotation {
hir::BindingAnnotation::REF => match result {
None | Some(hir::Mutability::Not) => result = Some(hir::Mutability::Not),
_ => {}
},
hir::BindingAnnotation::REF_MUT => result = Some(hir::Mutability::Mut),
_ => {}
});
result
}
pub fn for_loop_some(&self) -> Option<&Self> {
if self.span.desugaring_kind() == Some(DesugaringKind::ForLoop) {
if let hir::PatKind::Struct(_, [pat_field], _) = self.kind {
return Some(pat_field.pat);
}
}
None
}
}