rustc_data_structures/
unord.rs

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1//! This module contains collection types that don't expose their internal
2//! ordering. This is a useful property for deterministic computations, such
3//! as required by the query system.
4
5use std::borrow::{Borrow, BorrowMut};
6use std::collections::hash_map::{Entry, OccupiedError};
7use std::hash::Hash;
8use std::iter::{Product, Sum};
9use std::ops::Index;
10
11use rustc_hash::{FxHashMap, FxHashSet};
12use rustc_macros::{Decodable_Generic, Encodable_Generic};
13
14use crate::fingerprint::Fingerprint;
15use crate::stable_hasher::{HashStable, StableCompare, StableHasher, ToStableHashKey};
16
17/// `UnordItems` is the order-less version of `Iterator`. It only contains methods
18/// that don't (easily) expose an ordering of the underlying items.
19///
20/// Most methods take an `Fn` where the `Iterator`-version takes an `FnMut`. This
21/// is to reduce the risk of accidentally leaking the internal order via the closure
22/// environment. Otherwise one could easily do something like
23///
24/// ```rust,ignore (pseudo code)
25/// let mut ordered = vec![];
26/// unordered_items.all(|x| ordered.push(x));
27/// ```
28///
29/// It's still possible to do the same thing with an `Fn` by using interior mutability,
30/// but the chance of doing it accidentally is reduced.
31#[derive(Clone)]
32pub struct UnordItems<T, I: Iterator<Item = T>>(I);
33
34impl<T, I: Iterator<Item = T>> UnordItems<T, I> {
35    #[inline]
36    pub fn map<U, F: Fn(T) -> U>(self, f: F) -> UnordItems<U, impl Iterator<Item = U>> {
37        UnordItems(self.0.map(f))
38    }
39
40    #[inline]
41    pub fn all<F: Fn(T) -> bool>(mut self, f: F) -> bool {
42        self.0.all(f)
43    }
44
45    #[inline]
46    pub fn any<F: Fn(T) -> bool>(mut self, f: F) -> bool {
47        self.0.any(f)
48    }
49
50    #[inline]
51    pub fn filter<F: Fn(&T) -> bool>(self, f: F) -> UnordItems<T, impl Iterator<Item = T>> {
52        UnordItems(self.0.filter(f))
53    }
54
55    #[inline]
56    pub fn filter_map<U, F: Fn(T) -> Option<U>>(
57        self,
58        f: F,
59    ) -> UnordItems<U, impl Iterator<Item = U>> {
60        UnordItems(self.0.filter_map(f))
61    }
62
63    #[inline]
64    pub fn max(self) -> Option<T>
65    where
66        T: Ord,
67    {
68        self.0.max()
69    }
70
71    #[inline]
72    pub fn min(self) -> Option<T>
73    where
74        T: Ord,
75    {
76        self.0.min()
77    }
78
79    #[inline]
80    pub fn sum<S>(self) -> S
81    where
82        S: Sum<T>,
83    {
84        self.0.sum()
85    }
86
87    #[inline]
88    pub fn product<S>(self) -> S
89    where
90        S: Product<T>,
91    {
92        self.0.product()
93    }
94
95    #[inline]
96    pub fn count(self) -> usize {
97        self.0.count()
98    }
99
100    #[inline]
101    pub fn flat_map<U, F, O>(self, f: F) -> UnordItems<O, impl Iterator<Item = O>>
102    where
103        U: IntoIterator<Item = O>,
104        F: Fn(T) -> U,
105    {
106        UnordItems(self.0.flat_map(f))
107    }
108
109    pub fn collect<C: From<UnordItems<T, I>>>(self) -> C {
110        self.into()
111    }
112}
113
114impl<T> UnordItems<T, std::iter::Empty<T>> {
115    pub fn empty() -> Self {
116        UnordItems(std::iter::empty())
117    }
118}
119
120impl<'a, T: Clone + 'a, I: Iterator<Item = &'a T>> UnordItems<&'a T, I> {
121    #[inline]
122    pub fn cloned(self) -> UnordItems<T, impl Iterator<Item = T>> {
123        UnordItems(self.0.cloned())
124    }
125}
126
127impl<'a, T: Copy + 'a, I: Iterator<Item = &'a T>> UnordItems<&'a T, I> {
128    #[inline]
129    pub fn copied(self) -> UnordItems<T, impl Iterator<Item = T>> {
130        UnordItems(self.0.copied())
131    }
132}
133
134impl<T, I: Iterator<Item = T>> UnordItems<T, I> {
135    #[inline]
136    pub fn into_sorted<HCX>(self, hcx: &HCX) -> Vec<T>
137    where
138        T: ToStableHashKey<HCX>,
139    {
140        self.collect_sorted(hcx, true)
141    }
142
143    #[inline]
144    pub fn into_sorted_stable_ord(self) -> Vec<T>
145    where
146        T: StableCompare,
147    {
148        self.collect_stable_ord_by_key(|x| x)
149    }
150
151    #[inline]
152    pub fn into_sorted_stable_ord_by_key<K, C>(self, project_to_key: C) -> Vec<T>
153    where
154        K: StableCompare,
155        C: for<'a> Fn(&'a T) -> &'a K,
156    {
157        self.collect_stable_ord_by_key(project_to_key)
158    }
159
160    #[inline]
161    pub fn collect_sorted<HCX, C>(self, hcx: &HCX, cache_sort_key: bool) -> C
162    where
163        T: ToStableHashKey<HCX>,
164        C: FromIterator<T> + BorrowMut<[T]>,
165    {
166        let mut items: C = self.0.collect();
167
168        let slice = items.borrow_mut();
169        if slice.len() > 1 {
170            if cache_sort_key {
171                slice.sort_by_cached_key(|x| x.to_stable_hash_key(hcx));
172            } else {
173                slice.sort_by_key(|x| x.to_stable_hash_key(hcx));
174            }
175        }
176
177        items
178    }
179
180    #[inline]
181    pub fn collect_stable_ord_by_key<K, C, P>(self, project_to_key: P) -> C
182    where
183        K: StableCompare,
184        P: for<'a> Fn(&'a T) -> &'a K,
185        C: FromIterator<T> + BorrowMut<[T]>,
186    {
187        let mut items: C = self.0.collect();
188
189        let slice = items.borrow_mut();
190        if slice.len() > 1 {
191            if !K::CAN_USE_UNSTABLE_SORT {
192                slice.sort_by(|a, b| {
193                    let a_key = project_to_key(a);
194                    let b_key = project_to_key(b);
195                    a_key.stable_cmp(b_key)
196                });
197            } else {
198                slice.sort_unstable_by(|a, b| {
199                    let a_key = project_to_key(a);
200                    let b_key = project_to_key(b);
201                    a_key.stable_cmp(b_key)
202                });
203            }
204        }
205
206        items
207    }
208}
209
210/// A marker trait specifying that `Self` can consume `UnordItems<_>` without
211/// exposing any internal ordering.
212///
213/// Note: right now this is just a marker trait. It could be extended to contain
214/// some useful, common methods though, like `len`, `clear`, or the various
215/// kinds of `to_sorted`.
216trait UnordCollection {}
217
218/// This is a set collection type that tries very hard to not expose
219/// any internal iteration. This is a useful property when trying to
220/// uphold the determinism invariants imposed by the query system.
221///
222/// This collection type is a good choice for set-like collections the
223/// keys of which don't have a semantic ordering.
224///
225/// See [MCP 533](https://github.com/rust-lang/compiler-team/issues/533)
226/// for more information.
227#[derive(Debug, Eq, PartialEq, Clone, Encodable_Generic, Decodable_Generic)]
228pub struct UnordSet<V: Eq + Hash> {
229    inner: FxHashSet<V>,
230}
231
232impl<V: Eq + Hash> UnordCollection for UnordSet<V> {}
233
234impl<V: Eq + Hash> Default for UnordSet<V> {
235    #[inline]
236    fn default() -> Self {
237        Self { inner: FxHashSet::default() }
238    }
239}
240
241impl<V: Eq + Hash> UnordSet<V> {
242    #[inline]
243    pub fn new() -> Self {
244        Self { inner: Default::default() }
245    }
246
247    #[inline]
248    pub fn with_capacity(capacity: usize) -> Self {
249        Self { inner: FxHashSet::with_capacity_and_hasher(capacity, Default::default()) }
250    }
251
252    #[inline]
253    pub fn len(&self) -> usize {
254        self.inner.len()
255    }
256
257    #[inline]
258    pub fn is_empty(&self) -> bool {
259        self.inner.is_empty()
260    }
261
262    #[inline]
263    pub fn insert(&mut self, v: V) -> bool {
264        self.inner.insert(v)
265    }
266
267    #[inline]
268    pub fn contains<Q: ?Sized>(&self, v: &Q) -> bool
269    where
270        V: Borrow<Q>,
271        Q: Hash + Eq,
272    {
273        self.inner.contains(v)
274    }
275
276    #[inline]
277    pub fn remove<Q: ?Sized>(&mut self, k: &Q) -> bool
278    where
279        V: Borrow<Q>,
280        Q: Hash + Eq,
281    {
282        self.inner.remove(k)
283    }
284
285    #[inline]
286    pub fn items(&self) -> UnordItems<&V, impl Iterator<Item = &V>> {
287        UnordItems(self.inner.iter())
288    }
289
290    #[inline]
291    pub fn into_items(self) -> UnordItems<V, impl Iterator<Item = V>> {
292        UnordItems(self.inner.into_iter())
293    }
294
295    /// Returns the items of this set in stable sort order (as defined by `ToStableHashKey`).
296    ///
297    /// The `cache_sort_key` parameter controls if [slice::sort_by_cached_key] or
298    /// [slice::sort_unstable_by_key] will be used for sorting the vec. Use
299    /// `cache_sort_key` when the [ToStableHashKey::to_stable_hash_key] implementation
300    /// for `V` is expensive (e.g. a `DefId -> DefPathHash` lookup).
301    #[inline]
302    pub fn to_sorted<HCX>(&self, hcx: &HCX, cache_sort_key: bool) -> Vec<&V>
303    where
304        V: ToStableHashKey<HCX>,
305    {
306        to_sorted_vec(hcx, self.inner.iter(), cache_sort_key, |&x| x)
307    }
308
309    /// Returns the items of this set in stable sort order (as defined by
310    /// `StableCompare`). This method is much more efficient than
311    /// `into_sorted` because it does not need to transform keys to their
312    /// `ToStableHashKey` equivalent.
313    #[inline]
314    pub fn to_sorted_stable_ord(&self) -> Vec<&V>
315    where
316        V: StableCompare,
317    {
318        let mut items: Vec<&V> = self.inner.iter().collect();
319        items.sort_unstable_by(|a, b| a.stable_cmp(*b));
320        items
321    }
322
323    /// Returns the items of this set in stable sort order (as defined by
324    /// `StableCompare`). This method is much more efficient than
325    /// `into_sorted` because it does not need to transform keys to their
326    /// `ToStableHashKey` equivalent.
327    #[inline]
328    pub fn into_sorted_stable_ord(self) -> Vec<V>
329    where
330        V: StableCompare,
331    {
332        let mut items: Vec<V> = self.inner.into_iter().collect();
333        items.sort_unstable_by(V::stable_cmp);
334        items
335    }
336
337    /// Returns the items of this set in stable sort order (as defined by `ToStableHashKey`).
338    ///
339    /// The `cache_sort_key` parameter controls if [slice::sort_by_cached_key] or
340    /// [slice::sort_unstable_by_key] will be used for sorting the vec. Use
341    /// `cache_sort_key` when the [ToStableHashKey::to_stable_hash_key] implementation
342    /// for `V` is expensive (e.g. a `DefId -> DefPathHash` lookup).
343    #[inline]
344    pub fn into_sorted<HCX>(self, hcx: &HCX, cache_sort_key: bool) -> Vec<V>
345    where
346        V: ToStableHashKey<HCX>,
347    {
348        to_sorted_vec(hcx, self.inner.into_iter(), cache_sort_key, |x| x)
349    }
350
351    #[inline]
352    pub fn clear(&mut self) {
353        self.inner.clear();
354    }
355}
356
357pub trait ExtendUnord<T> {
358    /// Extend this unord collection with the given `UnordItems`.
359    /// This method is called `extend_unord` instead of just `extend` so it
360    /// does not conflict with `Extend::extend`. Otherwise there would be many
361    /// places where the two methods would have to be explicitly disambiguated
362    /// via UFCS.
363    fn extend_unord<I: Iterator<Item = T>>(&mut self, items: UnordItems<T, I>);
364}
365
366// Note: it is important that `C` implements `UnordCollection` in addition to
367// `Extend`, otherwise this impl would leak the internal iteration order of
368// `items`, e.g. when calling `some_vec.extend_unord(some_unord_items)`.
369impl<C: Extend<T> + UnordCollection, T> ExtendUnord<T> for C {
370    #[inline]
371    fn extend_unord<I: Iterator<Item = T>>(&mut self, items: UnordItems<T, I>) {
372        self.extend(items.0)
373    }
374}
375
376impl<V: Hash + Eq> Extend<V> for UnordSet<V> {
377    #[inline]
378    fn extend<T: IntoIterator<Item = V>>(&mut self, iter: T) {
379        self.inner.extend(iter)
380    }
381}
382
383impl<V: Hash + Eq> FromIterator<V> for UnordSet<V> {
384    #[inline]
385    fn from_iter<T: IntoIterator<Item = V>>(iter: T) -> Self {
386        UnordSet { inner: FxHashSet::from_iter(iter) }
387    }
388}
389
390impl<V: Hash + Eq> From<FxHashSet<V>> for UnordSet<V> {
391    fn from(value: FxHashSet<V>) -> Self {
392        UnordSet { inner: value }
393    }
394}
395
396impl<V: Hash + Eq, I: Iterator<Item = V>> From<UnordItems<V, I>> for UnordSet<V> {
397    fn from(value: UnordItems<V, I>) -> Self {
398        UnordSet { inner: FxHashSet::from_iter(value.0) }
399    }
400}
401
402impl<HCX, V: Hash + Eq + HashStable<HCX>> HashStable<HCX> for UnordSet<V> {
403    #[inline]
404    fn hash_stable(&self, hcx: &mut HCX, hasher: &mut StableHasher) {
405        hash_iter_order_independent(self.inner.iter(), hcx, hasher);
406    }
407}
408
409/// This is a map collection type that tries very hard to not expose
410/// any internal iteration. This is a useful property when trying to
411/// uphold the determinism invariants imposed by the query system.
412///
413/// This collection type is a good choice for map-like collections the
414/// keys of which don't have a semantic ordering.
415///
416/// See [MCP 533](https://github.com/rust-lang/compiler-team/issues/533)
417/// for more information.
418#[derive(Debug, Eq, PartialEq, Clone, Encodable_Generic, Decodable_Generic)]
419pub struct UnordMap<K: Eq + Hash, V> {
420    inner: FxHashMap<K, V>,
421}
422
423impl<K: Eq + Hash, V> UnordCollection for UnordMap<K, V> {}
424
425impl<K: Eq + Hash, V> Default for UnordMap<K, V> {
426    #[inline]
427    fn default() -> Self {
428        Self { inner: FxHashMap::default() }
429    }
430}
431
432impl<K: Hash + Eq, V> Extend<(K, V)> for UnordMap<K, V> {
433    #[inline]
434    fn extend<T: IntoIterator<Item = (K, V)>>(&mut self, iter: T) {
435        self.inner.extend(iter)
436    }
437}
438
439impl<K: Hash + Eq, V> FromIterator<(K, V)> for UnordMap<K, V> {
440    #[inline]
441    fn from_iter<T: IntoIterator<Item = (K, V)>>(iter: T) -> Self {
442        UnordMap { inner: FxHashMap::from_iter(iter) }
443    }
444}
445
446impl<K: Hash + Eq, V, I: Iterator<Item = (K, V)>> From<UnordItems<(K, V), I>> for UnordMap<K, V> {
447    #[inline]
448    fn from(items: UnordItems<(K, V), I>) -> Self {
449        UnordMap { inner: FxHashMap::from_iter(items.0) }
450    }
451}
452
453impl<K: Eq + Hash, V> UnordMap<K, V> {
454    #[inline]
455    pub fn with_capacity(capacity: usize) -> Self {
456        Self { inner: FxHashMap::with_capacity_and_hasher(capacity, Default::default()) }
457    }
458
459    #[inline]
460    pub fn len(&self) -> usize {
461        self.inner.len()
462    }
463
464    #[inline]
465    pub fn insert(&mut self, k: K, v: V) -> Option<V> {
466        self.inner.insert(k, v)
467    }
468
469    #[inline]
470    pub fn try_insert(&mut self, k: K, v: V) -> Result<&mut V, OccupiedError<'_, K, V>> {
471        self.inner.try_insert(k, v)
472    }
473
474    #[inline]
475    pub fn contains_key<Q: ?Sized>(&self, k: &Q) -> bool
476    where
477        K: Borrow<Q>,
478        Q: Hash + Eq,
479    {
480        self.inner.contains_key(k)
481    }
482
483    #[inline]
484    pub fn is_empty(&self) -> bool {
485        self.inner.is_empty()
486    }
487
488    #[inline]
489    pub fn entry(&mut self, key: K) -> Entry<'_, K, V> {
490        self.inner.entry(key)
491    }
492
493    #[inline]
494    pub fn get<Q: ?Sized>(&self, k: &Q) -> Option<&V>
495    where
496        K: Borrow<Q>,
497        Q: Hash + Eq,
498    {
499        self.inner.get(k)
500    }
501
502    #[inline]
503    pub fn get_mut<Q: ?Sized>(&mut self, k: &Q) -> Option<&mut V>
504    where
505        K: Borrow<Q>,
506        Q: Hash + Eq,
507    {
508        self.inner.get_mut(k)
509    }
510
511    #[inline]
512    pub fn remove<Q: ?Sized>(&mut self, k: &Q) -> Option<V>
513    where
514        K: Borrow<Q>,
515        Q: Hash + Eq,
516    {
517        self.inner.remove(k)
518    }
519
520    #[inline]
521    pub fn items(&self) -> UnordItems<(&K, &V), impl Iterator<Item = (&K, &V)>> {
522        UnordItems(self.inner.iter())
523    }
524
525    #[inline]
526    pub fn into_items(self) -> UnordItems<(K, V), impl Iterator<Item = (K, V)>> {
527        UnordItems(self.inner.into_iter())
528    }
529
530    #[inline]
531    pub fn keys(&self) -> UnordItems<&K, impl Iterator<Item = &K>> {
532        UnordItems(self.inner.keys())
533    }
534
535    /// Returns the entries of this map in stable sort order (as defined by `ToStableHashKey`).
536    ///
537    /// The `cache_sort_key` parameter controls if [slice::sort_by_cached_key] or
538    /// [slice::sort_unstable_by_key] will be used for sorting the vec. Use
539    /// `cache_sort_key` when the [ToStableHashKey::to_stable_hash_key] implementation
540    /// for `K` is expensive (e.g. a `DefId -> DefPathHash` lookup).
541    #[inline]
542    pub fn to_sorted<HCX>(&self, hcx: &HCX, cache_sort_key: bool) -> Vec<(&K, &V)>
543    where
544        K: ToStableHashKey<HCX>,
545    {
546        to_sorted_vec(hcx, self.inner.iter(), cache_sort_key, |&(k, _)| k)
547    }
548
549    /// Returns the entries of this map in stable sort order (as defined by `StableCompare`).
550    /// This method can be much more efficient than `into_sorted` because it does not need
551    /// to transform keys to their `ToStableHashKey` equivalent.
552    #[inline]
553    pub fn to_sorted_stable_ord(&self) -> Vec<(&K, &V)>
554    where
555        K: StableCompare,
556    {
557        let mut items: Vec<_> = self.inner.iter().collect();
558        items.sort_unstable_by(|(a, _), (b, _)| a.stable_cmp(*b));
559        items
560    }
561
562    /// Returns the entries of this map in stable sort order (as defined by `ToStableHashKey`).
563    ///
564    /// The `cache_sort_key` parameter controls if [slice::sort_by_cached_key] or
565    /// [slice::sort_unstable_by_key] will be used for sorting the vec. Use
566    /// `cache_sort_key` when the [ToStableHashKey::to_stable_hash_key] implementation
567    /// for `K` is expensive (e.g. a `DefId -> DefPathHash` lookup).
568    #[inline]
569    pub fn into_sorted<HCX>(self, hcx: &HCX, cache_sort_key: bool) -> Vec<(K, V)>
570    where
571        K: ToStableHashKey<HCX>,
572    {
573        to_sorted_vec(hcx, self.inner.into_iter(), cache_sort_key, |(k, _)| k)
574    }
575
576    /// Returns the entries of this map in stable sort order (as defined by `StableCompare`).
577    /// This method can be much more efficient than `into_sorted` because it does not need
578    /// to transform keys to their `ToStableHashKey` equivalent.
579    #[inline]
580    pub fn into_sorted_stable_ord(self) -> Vec<(K, V)>
581    where
582        K: StableCompare,
583    {
584        let mut items: Vec<(K, V)> = self.inner.into_iter().collect();
585        items.sort_unstable_by(|a, b| a.0.stable_cmp(&b.0));
586        items
587    }
588
589    /// Returns the values of this map in stable sort order (as defined by K's
590    /// `ToStableHashKey` implementation).
591    ///
592    /// The `cache_sort_key` parameter controls if [slice::sort_by_cached_key] or
593    /// [slice::sort_unstable_by_key] will be used for sorting the vec. Use
594    /// `cache_sort_key` when the [ToStableHashKey::to_stable_hash_key] implementation
595    /// for `K` is expensive (e.g. a `DefId -> DefPathHash` lookup).
596    #[inline]
597    pub fn values_sorted<HCX>(&self, hcx: &HCX, cache_sort_key: bool) -> impl Iterator<Item = &V>
598    where
599        K: ToStableHashKey<HCX>,
600    {
601        to_sorted_vec(hcx, self.inner.iter(), cache_sort_key, |&(k, _)| k)
602            .into_iter()
603            .map(|(_, v)| v)
604    }
605
606    #[inline]
607    pub fn clear(&mut self) {
608        self.inner.clear()
609    }
610}
611
612impl<K, Q: ?Sized, V> Index<&Q> for UnordMap<K, V>
613where
614    K: Eq + Hash + Borrow<Q>,
615    Q: Eq + Hash,
616{
617    type Output = V;
618
619    #[inline]
620    fn index(&self, key: &Q) -> &V {
621        &self.inner[key]
622    }
623}
624
625impl<HCX, K: Hash + Eq + HashStable<HCX>, V: HashStable<HCX>> HashStable<HCX> for UnordMap<K, V> {
626    #[inline]
627    fn hash_stable(&self, hcx: &mut HCX, hasher: &mut StableHasher) {
628        hash_iter_order_independent(self.inner.iter(), hcx, hasher);
629    }
630}
631
632/// This is a collection type that tries very hard to not expose
633/// any internal iteration. This is a useful property when trying to
634/// uphold the determinism invariants imposed by the query system.
635///
636/// This collection type is a good choice for collections the
637/// keys of which don't have a semantic ordering and don't implement
638/// `Hash` or `Eq`.
639///
640/// See [MCP 533](https://github.com/rust-lang/compiler-team/issues/533)
641/// for more information.
642#[derive(Default, Debug, Eq, PartialEq, Clone, Encodable_Generic, Decodable_Generic)]
643pub struct UnordBag<V> {
644    inner: Vec<V>,
645}
646
647impl<V> UnordBag<V> {
648    #[inline]
649    pub fn new() -> Self {
650        Self { inner: Default::default() }
651    }
652
653    #[inline]
654    pub fn len(&self) -> usize {
655        self.inner.len()
656    }
657
658    #[inline]
659    pub fn push(&mut self, v: V) {
660        self.inner.push(v);
661    }
662
663    #[inline]
664    pub fn items(&self) -> UnordItems<&V, impl Iterator<Item = &V>> {
665        UnordItems(self.inner.iter())
666    }
667
668    #[inline]
669    pub fn into_items(self) -> UnordItems<V, impl Iterator<Item = V>> {
670        UnordItems(self.inner.into_iter())
671    }
672}
673
674impl<T> UnordCollection for UnordBag<T> {}
675
676impl<T> Extend<T> for UnordBag<T> {
677    fn extend<I: IntoIterator<Item = T>>(&mut self, iter: I) {
678        self.inner.extend(iter)
679    }
680}
681
682impl<T, I: Iterator<Item = T>> From<UnordItems<T, I>> for UnordBag<T> {
683    fn from(value: UnordItems<T, I>) -> Self {
684        UnordBag { inner: Vec::from_iter(value.0) }
685    }
686}
687
688impl<HCX, V: Hash + Eq + HashStable<HCX>> HashStable<HCX> for UnordBag<V> {
689    #[inline]
690    fn hash_stable(&self, hcx: &mut HCX, hasher: &mut StableHasher) {
691        hash_iter_order_independent(self.inner.iter(), hcx, hasher);
692    }
693}
694
695#[inline]
696fn to_sorted_vec<HCX, T, K, I>(
697    hcx: &HCX,
698    iter: I,
699    cache_sort_key: bool,
700    extract_key: fn(&T) -> &K,
701) -> Vec<T>
702where
703    I: Iterator<Item = T>,
704    K: ToStableHashKey<HCX>,
705{
706    let mut items: Vec<T> = iter.collect();
707    if cache_sort_key {
708        items.sort_by_cached_key(|x| extract_key(x).to_stable_hash_key(hcx));
709    } else {
710        items.sort_unstable_by_key(|x| extract_key(x).to_stable_hash_key(hcx));
711    }
712
713    items
714}
715
716fn hash_iter_order_independent<
717    HCX,
718    T: HashStable<HCX>,
719    I: Iterator<Item = T> + ExactSizeIterator,
720>(
721    mut it: I,
722    hcx: &mut HCX,
723    hasher: &mut StableHasher,
724) {
725    let len = it.len();
726    len.hash_stable(hcx, hasher);
727
728    match len {
729        0 => {
730            // We're done
731        }
732        1 => {
733            // No need to instantiate a hasher
734            it.next().unwrap().hash_stable(hcx, hasher);
735        }
736        _ => {
737            let mut accumulator = Fingerprint::ZERO;
738            for item in it {
739                let mut item_hasher = StableHasher::new();
740                item.hash_stable(hcx, &mut item_hasher);
741                let item_fingerprint: Fingerprint = item_hasher.finish();
742                accumulator = accumulator.combine_commutative(item_fingerprint);
743            }
744            accumulator.hash_stable(hcx, hasher);
745        }
746    }
747}
748
749// Do not implement IntoIterator for the collections in this module.
750// They only exist to hide iteration order in the first place.
751impl<T> !IntoIterator for UnordBag<T> {}
752impl<V> !IntoIterator for UnordSet<V> {}
753impl<K, V> !IntoIterator for UnordMap<K, V> {}
754impl<T, I> !IntoIterator for UnordItems<T, I> {}
rustc_data_structures/unord.rs

rustc_data_structures/
unord.rs
