snix_eval/value/
attrs.rs

1//! This module implements Nix attribute sets. They have flexible
2//! backing implementations, as they are used in very versatile
3//! use-cases that are all exposed the same way in the language
4//! surface.
5//!
6//! Due to this, construction and management of attribute sets has
7//! some peculiarities that are encapsulated within this module.
8use std::borrow::Borrow;
9use std::collections::{BTreeMap, hash_map};
10use std::iter::FromIterator;
11use std::rc::Rc;
12use std::sync::LazyLock;
13
14use bstr::BStr;
15use itertools::Itertools as _;
16use rustc_hash::FxHashMap;
17use serde::Deserialize;
18use serde::de::{Deserializer, Error, Visitor};
19
20use super::TotalDisplay;
21use super::Value;
22use super::string::NixString;
23use super::thunk::ThunkSet;
24use crate::CatchableErrorKind;
25use crate::errors::ErrorKind;
26
27static NAME: LazyLock<NixString> = LazyLock::new(|| "name".into());
28static VALUE: LazyLock<NixString> = LazyLock::new(|| "value".into());
29
30#[cfg(test)]
31mod tests;
32
33#[derive(Clone, Debug, Deserialize, Default)]
34pub(super) enum AttrsRep {
35    #[default]
36    Empty,
37
38    Map(FxHashMap<NixString, Value>),
39
40    /// Warning: this represents a **two**-attribute attrset, with
41    /// attribute names "name" and "value", like `{name="foo";
42    /// value="bar";}`, *not* `{foo="bar";}`!
43    KV {
44        name: Value,
45        value: Value,
46    },
47}
48
49impl AttrsRep {
50    fn select(&self, key: &BStr) -> Option<&Value> {
51        match self {
52            AttrsRep::Empty => None,
53
54            AttrsRep::KV { name, value } => match &**key {
55                b"name" => Some(name),
56                b"value" => Some(value),
57                _ => None,
58            },
59
60            AttrsRep::Map(map) => map.get(key),
61        }
62    }
63
64    fn contains(&self, key: &BStr) -> bool {
65        match self {
66            AttrsRep::Empty => false,
67            AttrsRep::KV { .. } => key == "name" || key == "value",
68            AttrsRep::Map(map) => map.contains_key(key),
69        }
70    }
71}
72
73#[repr(transparent)]
74#[derive(Clone, Debug, Default)]
75pub struct NixAttrs(pub(super) Rc<AttrsRep>);
76
77impl From<AttrsRep> for NixAttrs {
78    fn from(rep: AttrsRep) -> Self {
79        NixAttrs(Rc::new(rep))
80    }
81}
82
83impl<K, V> FromIterator<(K, V)> for NixAttrs
84where
85    NixString: From<K>,
86    Value: From<V>,
87{
88    fn from_iter<T>(iter: T) -> NixAttrs
89    where
90        T: IntoIterator<Item = (K, V)>,
91    {
92        AttrsRep::Map(
93            iter.into_iter()
94                .map(|(k, v)| (k.into(), v.into()))
95                .collect(),
96        )
97        .into()
98    }
99}
100
101impl From<BTreeMap<NixString, Value>> for NixAttrs {
102    fn from(map: BTreeMap<NixString, Value>) -> Self {
103        AttrsRep::Map(map.into_iter().collect()).into()
104    }
105}
106
107impl From<FxHashMap<NixString, Value>> for NixAttrs {
108    fn from(map: FxHashMap<NixString, Value>) -> Self {
109        AttrsRep::Map(map).into()
110    }
111}
112
113impl TotalDisplay for NixAttrs {
114    fn total_fmt(&self, f: &mut std::fmt::Formatter<'_>, set: &mut ThunkSet) -> std::fmt::Result {
115        if let Some(Value::String(s)) = self.select("type") {
116            if *s == "derivation" {
117                write!(f, "«derivation ")?;
118                if let Some(p) = self.select("drvPath") {
119                    p.total_fmt(f, set)?;
120                } else {
121                    write!(f, "???")?;
122                }
123                return write!(f, "»");
124            }
125        }
126
127        f.write_str("{ ")?;
128
129        for (name, value) in self.iter_sorted() {
130            write!(f, "{} = ", name.ident_str())?;
131            value.total_fmt(f, set)?;
132            f.write_str("; ")?;
133        }
134
135        f.write_str("}")
136    }
137}
138
139impl<'de> Deserialize<'de> for NixAttrs {
140    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
141    where
142        D: Deserializer<'de>,
143    {
144        struct MapVisitor;
145
146        impl<'de> Visitor<'de> for MapVisitor {
147            type Value = NixAttrs;
148
149            fn expecting(&self, formatter: &mut std::fmt::Formatter) -> std::fmt::Result {
150                formatter.write_str("a valid Nix attribute set")
151            }
152
153            fn visit_map<A>(self, mut map: A) -> Result<Self::Value, A::Error>
154            where
155                A: serde::de::MapAccess<'de>,
156            {
157                let mut stack_array = Vec::with_capacity(map.size_hint().unwrap_or(0) * 2);
158
159                while let Some((key, value)) = map.next_entry()? {
160                    stack_array.push(key);
161                    stack_array.push(value);
162                }
163
164                Ok(NixAttrs::construct(stack_array.len() / 2, stack_array)
165                    .map_err(A::Error::custom)?
166                    .expect("Catchable values are unreachable here"))
167            }
168        }
169
170        deserializer.deserialize_map(MapVisitor)
171    }
172}
173
174impl NixAttrs {
175    pub fn empty() -> Self {
176        AttrsRep::Empty.into()
177    }
178
179    /// Compare two attribute sets by pointer equality. Only makes
180    /// sense for some attribute set representations, i.e. returning
181    /// `false` does not mean that the two attribute sets do not have
182    /// equal *content*.
183    pub fn ptr_eq(&self, other: &Self) -> bool {
184        Rc::ptr_eq(&self.0, &other.0)
185    }
186
187    /// Return an attribute set containing the merge of the two
188    /// provided sets. Keys from the `other` set have precedence.
189    pub fn update(self, other: Self) -> Self {
190        // Short-circuit on some optimal cases:
191        match (self.0.as_ref(), other.0.as_ref()) {
192            (AttrsRep::Empty, AttrsRep::Empty) => return self,
193            (AttrsRep::Empty, _) => return other,
194            (_, AttrsRep::Empty) => return self,
195            (AttrsRep::KV { .. }, AttrsRep::KV { .. }) => return other,
196
197            // Explicitly handle all branches instead of falling
198            // through, to ensure that we get at least some compiler
199            // errors if variants are modified.
200            (AttrsRep::Map(_), AttrsRep::Map(_))
201            | (AttrsRep::Map(_), AttrsRep::KV { .. })
202            | (AttrsRep::KV { .. }, AttrsRep::Map(_)) => {}
203        };
204
205        // Slightly more advanced, but still optimised updates
206        match (Rc::unwrap_or_clone(self.0), Rc::unwrap_or_clone(other.0)) {
207            (AttrsRep::Map(mut m), AttrsRep::KV { name, value }) => {
208                m.insert(NAME.clone(), name);
209                m.insert(VALUE.clone(), value);
210                AttrsRep::Map(m).into()
211            }
212
213            (AttrsRep::KV { name, value }, AttrsRep::Map(mut m)) => {
214                match m.entry(NAME.clone()) {
215                    hash_map::Entry::Vacant(e) => {
216                        e.insert(name);
217                    }
218
219                    hash_map::Entry::Occupied(_) => { /* name from `m` has precedence */ }
220                };
221
222                match m.entry(VALUE.clone()) {
223                    hash_map::Entry::Vacant(e) => {
224                        e.insert(value);
225                    }
226
227                    hash_map::Entry::Occupied(_) => { /* value from `m` has precedence */ }
228                };
229
230                AttrsRep::Map(m).into()
231            }
232
233            // Plain merge of maps.
234            (AttrsRep::Map(mut m1), AttrsRep::Map(mut m2)) => {
235                let map = if m1.len() >= m2.len() {
236                    m1.extend(m2);
237                    m1
238                } else {
239                    for (key, val) in m1.into_iter() {
240                        m2.entry(key).or_insert(val);
241                    }
242                    m2
243                };
244                AttrsRep::Map(map).into()
245            }
246
247            // Cases handled above by the borrowing match:
248            _ => unreachable!(),
249        }
250    }
251
252    /// Return the number of key-value entries in an attrset.
253    pub fn len(&self) -> usize {
254        match self.0.as_ref() {
255            AttrsRep::Map(map) => map.len(),
256            AttrsRep::Empty => 0,
257            AttrsRep::KV { .. } => 2,
258        }
259    }
260
261    pub fn is_empty(&self) -> bool {
262        match self.0.as_ref() {
263            AttrsRep::Map(map) => map.is_empty(),
264            AttrsRep::Empty => true,
265            AttrsRep::KV { .. } => false,
266        }
267    }
268
269    /// Select a value from an attribute set by key.
270    pub fn select<K>(&self, key: &K) -> Option<&Value>
271    where
272        K: Borrow<BStr> + ?Sized,
273    {
274        self.0.select(key.borrow())
275    }
276
277    /// Select a required value from an attribute set by key, return
278    /// an `AttributeNotFound` error if it is missing.
279    pub fn select_required<K>(&self, key: &K) -> Result<&Value, ErrorKind>
280    where
281        K: Borrow<BStr> + ?Sized,
282    {
283        self.select(key)
284            .ok_or_else(|| ErrorKind::AttributeNotFound {
285                name: key.borrow().to_string(),
286            })
287    }
288
289    pub fn contains<'a, K: 'a>(&self, key: K) -> bool
290    where
291        &'a BStr: From<K>,
292    {
293        self.0.contains(key.into())
294    }
295
296    /// Construct an iterator over all the key-value pairs in the attribute set.
297    #[allow(clippy::needless_lifetimes)]
298    pub fn iter<'a>(&'a self) -> Iter<KeyValue<'a>> {
299        Iter(match &self.0.as_ref() {
300            AttrsRep::Map(map) => KeyValue::Map(map.iter()),
301            AttrsRep::Empty => KeyValue::Empty,
302
303            AttrsRep::KV { name, value } => KeyValue::KV {
304                name,
305                value,
306                at: IterKV::default(),
307            },
308        })
309    }
310
311    /// Same as iter(), but marks call sites which rely on the
312    /// iteration being lexicographic.
313    pub fn iter_sorted(&self) -> Iter<KeyValue<'_>> {
314        Iter(match self.0.as_ref() {
315            AttrsRep::Empty => KeyValue::Empty,
316            AttrsRep::Map(map) => {
317                let sorted = map.iter().sorted_by_key(|x| x.0);
318                KeyValue::Sorted(sorted)
319            }
320            AttrsRep::KV { name, value } => KeyValue::KV {
321                name,
322                value,
323                at: IterKV::default(),
324            },
325        })
326    }
327
328    /// Same as [IntoIterator::into_iter], but marks call sites which rely on the
329    /// iteration being lexicographic.
330    pub fn into_iter_sorted(self) -> OwnedAttrsIterator {
331        let iter = match Rc::<AttrsRep>::try_unwrap(self.0) {
332            Ok(attrs) => match attrs {
333                AttrsRep::Empty => IntoIterRepr::Empty,
334                AttrsRep::Map(map) => {
335                    IntoIterRepr::Finite(map.into_iter().sorted_by(|(a, _), (b, _)| a.cmp(b)))
336                }
337                AttrsRep::KV { name, value } => IntoIterRepr::Finite(
338                    vec![(NAME.clone(), name), (VALUE.clone(), value)].into_iter(),
339                ),
340            },
341            Err(rc) => match rc.as_ref() {
342                AttrsRep::Empty => IntoIterRepr::Empty,
343                AttrsRep::Map(map) => IntoIterRepr::Finite(
344                    map.iter()
345                        .map(|(k, v)| (k.clone(), v.clone()))
346                        .sorted_by(|(a, _), (b, _)| a.cmp(b)),
347                ),
348                AttrsRep::KV { name, value } => IntoIterRepr::Finite(
349                    vec![(NAME.clone(), name.clone()), (VALUE.clone(), value.clone())].into_iter(),
350                ),
351            },
352        };
353        OwnedAttrsIterator(iter)
354    }
355
356    /// Construct an iterator over all the keys of the attribute set
357    pub fn keys(&self) -> Keys {
358        Keys(match self.0.as_ref() {
359            AttrsRep::Empty => KeysInner::Empty,
360            AttrsRep::KV { .. } => KeysInner::KV(IterKV::default()),
361
362            // TODO(tazjin): only sort when required, not always.
363            AttrsRep::Map(m) => KeysInner::Map(m.keys()),
364        })
365    }
366
367    /// Same as [Self::keys], but marks call sites which rely on the
368    /// iteration being lexicographic.
369    pub fn keys_sorted(&self) -> Keys {
370        Keys(match self.0.as_ref() {
371            AttrsRep::Map(map) => KeysInner::Sorted(map.keys().sorted()),
372            AttrsRep::Empty => KeysInner::Empty,
373            AttrsRep::KV { .. } => KeysInner::KV(IterKV::default()),
374        })
375    }
376
377    /// Implement construction logic of an attribute set, to encapsulate
378    /// logic about attribute set optimisations inside of this module.
379    pub fn construct(
380        count: usize,
381        mut stack_slice: Vec<Value>,
382    ) -> Result<Result<Self, CatchableErrorKind>, ErrorKind> {
383        debug_assert!(
384            stack_slice.len() == count * 2,
385            "construct_attrs called with count == {}, but slice.len() == {}",
386            count,
387            stack_slice.len(),
388        );
389
390        // Optimisation: Empty attribute set
391        if count == 0 {
392            return Ok(Ok(AttrsRep::Empty.into()));
393        }
394
395        // Optimisation: KV pattern
396        if count == 2 {
397            if let Some(kv) = attempt_optimise_kv(&mut stack_slice) {
398                return Ok(Ok(kv));
399            }
400        }
401
402        let mut attrs_map = FxHashMap::with_capacity_and_hasher(count, rustc_hash::FxBuildHasher);
403
404        for _ in 0..count {
405            let value = stack_slice.pop().unwrap();
406            let key = stack_slice.pop().unwrap();
407
408            match key {
409                Value::String(ks) => set_attr(&mut attrs_map, ks, value)?,
410
411                Value::Null => {
412                    // This is in fact valid, but leads to the value
413                    // being ignored and nothing being set, i.e. `{
414                    // ${null} = 1; } => { }`.
415                    continue;
416                }
417
418                Value::Catchable(err) => return Ok(Err(*err)),
419
420                other => return Err(ErrorKind::InvalidAttributeName(other)),
421            }
422        }
423
424        Ok(Ok(AttrsRep::Map(attrs_map).into()))
425    }
426
427    /// Construct an optimized "KV"-style attribute set given the value for the
428    /// `"name"` key, and the value for the `"value"` key
429    pub(crate) fn from_kv(name: Value, value: Value) -> Self {
430        AttrsRep::KV { name, value }.into()
431    }
432
433    /// Calculate the intersection of the attribute sets.
434    /// The right side value is used when the keys match.
435    pub(crate) fn intersect(&self, other: &Self) -> NixAttrs {
436        match (self.0.as_ref(), other.0.as_ref()) {
437            (AttrsRep::Empty, _) | (_, AttrsRep::Empty) => AttrsRep::Empty.into(),
438            (AttrsRep::Map(lhs), AttrsRep::Map(rhs)) => {
439                let mut out = FxHashMap::with_capacity_and_hasher(
440                    std::cmp::min(lhs.len(), rhs.len()),
441                    rustc_hash::FxBuildHasher,
442                );
443                if lhs.len() < rhs.len() {
444                    for key in lhs.keys() {
445                        if let Some(val) = rhs.get(key) {
446                            out.insert(key.clone(), val.clone());
447                        }
448                    }
449                } else {
450                    for (key, val) in rhs.iter() {
451                        if lhs.contains_key(key) {
452                            out.insert(key.clone(), val.clone());
453                        }
454                    }
455                };
456                out.into()
457            }
458            (AttrsRep::Map(map), AttrsRep::KV { name, value }) => {
459                let mut out = FxHashMap::with_capacity_and_hasher(2, rustc_hash::FxBuildHasher);
460                if map.contains_key(NAME.as_bstr()) {
461                    out.insert(NAME.clone(), name.clone());
462                }
463                if map.contains_key(VALUE.as_bstr()) {
464                    out.insert(VALUE.clone(), value.clone());
465                }
466
467                if out.is_empty() {
468                    NixAttrs::empty()
469                } else {
470                    out.into()
471                }
472            }
473            (AttrsRep::KV { .. }, AttrsRep::Map(map)) => {
474                let mut out = FxHashMap::with_capacity_and_hasher(2, rustc_hash::FxBuildHasher);
475                if let Some(name) = map.get(NAME.as_bstr()) {
476                    out.insert(NAME.clone(), name.clone());
477                }
478                if let Some(value) = map.get(VALUE.as_bstr()) {
479                    out.insert(VALUE.clone(), value.clone());
480                }
481
482                if out.is_empty() {
483                    NixAttrs::empty()
484                } else {
485                    out.into()
486                }
487            }
488            (AttrsRep::KV { .. }, AttrsRep::KV { .. }) => other.clone(),
489        }
490    }
491}
492
493impl IntoIterator for NixAttrs {
494    type Item = (NixString, Value);
495    type IntoIter = OwnedAttrsIterator;
496
497    fn into_iter(self) -> Self::IntoIter {
498        match Rc::unwrap_or_clone(self.0) {
499            AttrsRep::Empty => OwnedAttrsIterator(IntoIterRepr::Empty),
500            AttrsRep::KV { name, value } => OwnedAttrsIterator(IntoIterRepr::Finite(
501                vec![(NAME.clone(), name), (VALUE.clone(), value)].into_iter(),
502            )),
503            AttrsRep::Map(map) => OwnedAttrsIterator(IntoIterRepr::Map(map.into_iter())),
504        }
505    }
506}
507
508/// In Nix, name/value attribute pairs are frequently constructed from
509/// literals. This particular case should avoid allocation of a map,
510/// additional heap values etc. and use the optimised `KV` variant
511/// instead.
512///
513/// ```norust
514/// `slice` is the top of the stack from which the attrset is being
515/// constructed, e.g.
516///
517///   slice: [ "value" 5 "name" "foo" ]
518///   index:   0       1 2      3
519///   stack:   3       2 1      0
520/// ```
521fn attempt_optimise_kv(slice: &mut [Value]) -> Option<NixAttrs> {
522    let (name_idx, value_idx) = {
523        match (&slice[2], &slice[0]) {
524            (Value::String(s1), Value::String(s2)) if (*s1 == *NAME && *s2 == *VALUE) => (3, 1),
525            (Value::String(s1), Value::String(s2)) if (*s1 == *VALUE && *s2 == *NAME) => (1, 3),
526
527            // Technically this branch lets type errors pass,
528            // but they will be caught during normal attribute
529            // set construction instead.
530            _ => return None,
531        }
532    };
533
534    Some(NixAttrs::from_kv(
535        slice[name_idx].clone(),
536        slice[value_idx].clone(),
537    ))
538}
539
540/// Set an attribute on an in-construction attribute set, while
541/// checking against duplicate keys.
542fn set_attr(
543    map: &mut FxHashMap<NixString, Value>,
544    key: NixString,
545    value: Value,
546) -> Result<(), ErrorKind> {
547    match map.entry(key) {
548        hash_map::Entry::Occupied(entry) => Err(ErrorKind::DuplicateAttrsKey {
549            key: entry.key().to_string(),
550        }),
551
552        hash_map::Entry::Vacant(entry) => {
553            entry.insert(value);
554            Ok(())
555        }
556    }
557}
558
559/// Internal helper type to track the iteration status of an iterator
560/// over the name/value representation.
561#[derive(Debug, Default)]
562pub enum IterKV {
563    #[default]
564    Name,
565    Value,
566    Done,
567}
568
569impl IterKV {
570    fn next(&mut self) {
571        match *self {
572            Self::Name => *self = Self::Value,
573            Self::Value => *self = Self::Done,
574            Self::Done => {}
575        }
576    }
577}
578
579/// Iterator representation over the keys *and* values of an attribute
580/// set.
581pub enum KeyValue<'a> {
582    Empty,
583
584    KV {
585        name: &'a Value,
586        value: &'a Value,
587        at: IterKV,
588    },
589
590    Map(hash_map::Iter<'a, NixString, Value>),
591
592    Sorted(std::vec::IntoIter<(&'a NixString, &'a Value)>),
593}
594
595/// Iterator over a Nix attribute set.
596// This wrapper type exists to make the inner "raw" iterator
597// inaccessible.
598#[repr(transparent)]
599pub struct Iter<T>(T);
600
601impl<'a> Iterator for Iter<KeyValue<'a>> {
602    type Item = (&'a NixString, &'a Value);
603
604    fn next(&mut self) -> Option<Self::Item> {
605        match &mut self.0 {
606            KeyValue::Map(inner) => inner.next(),
607            KeyValue::Empty => None,
608            KeyValue::KV { name, value, at } => match at {
609                IterKV::Name => {
610                    at.next();
611                    Some((&NAME, name))
612                }
613
614                IterKV::Value => {
615                    at.next();
616                    Some((&VALUE, value))
617                }
618
619                IterKV::Done => None,
620            },
621            KeyValue::Sorted(inner) => inner.next(),
622        }
623    }
624}
625
626impl ExactSizeIterator for Iter<KeyValue<'_>> {
627    fn len(&self) -> usize {
628        match &self.0 {
629            KeyValue::Empty => 0,
630            KeyValue::KV { .. } => 2,
631            KeyValue::Map(inner) => inner.len(),
632            KeyValue::Sorted(inner) => inner.len(),
633        }
634    }
635}
636
637enum KeysInner<'a> {
638    Empty,
639    KV(IterKV),
640    Map(hash_map::Keys<'a, NixString, Value>),
641    Sorted(std::vec::IntoIter<&'a NixString>),
642}
643
644pub struct Keys<'a>(KeysInner<'a>);
645
646impl<'a> Iterator for Keys<'a> {
647    type Item = &'a NixString;
648
649    fn next(&mut self) -> Option<Self::Item> {
650        match &mut self.0 {
651            KeysInner::Empty => None,
652            KeysInner::KV(at @ IterKV::Name) => {
653                at.next();
654                Some(&NAME)
655            }
656            KeysInner::KV(at @ IterKV::Value) => {
657                at.next();
658                Some(&VALUE)
659            }
660            KeysInner::KV(IterKV::Done) => None,
661            KeysInner::Map(m) => m.next(),
662            KeysInner::Sorted(v) => v.next(),
663        }
664    }
665}
666
667impl<'a> IntoIterator for &'a NixAttrs {
668    type Item = (&'a NixString, &'a Value);
669
670    type IntoIter = Iter<KeyValue<'a>>;
671
672    fn into_iter(self) -> Self::IntoIter {
673        self.iter()
674    }
675}
676
677impl ExactSizeIterator for Keys<'_> {
678    fn len(&self) -> usize {
679        match &self.0 {
680            KeysInner::Empty => 0,
681            KeysInner::KV(_) => 2,
682            KeysInner::Map(m) => m.len(),
683            KeysInner::Sorted(v) => v.len(),
684        }
685    }
686}
687
688/// Internal representation of an owning attrset iterator
689pub enum IntoIterRepr {
690    Empty,
691    Finite(std::vec::IntoIter<(NixString, Value)>),
692    Map(hash_map::IntoIter<NixString, Value>),
693}
694
695/// Wrapper type which hides the internal implementation details from
696/// users.
697#[repr(transparent)]
698pub struct OwnedAttrsIterator(IntoIterRepr);
699
700impl Iterator for OwnedAttrsIterator {
701    type Item = (NixString, Value);
702
703    fn next(&mut self) -> Option<Self::Item> {
704        match &mut self.0 {
705            IntoIterRepr::Empty => None,
706            IntoIterRepr::Finite(inner) => inner.next(),
707            IntoIterRepr::Map(m) => m.next(),
708        }
709    }
710}
711
712impl ExactSizeIterator for OwnedAttrsIterator {
713    fn len(&self) -> usize {
714        match &self.0 {
715            IntoIterRepr::Empty => 0,
716            IntoIterRepr::Finite(inner) => inner.len(),
717            IntoIterRepr::Map(inner) => inner.len(),
718        }
719    }
720}
721
722impl DoubleEndedIterator for OwnedAttrsIterator {
723    fn next_back(&mut self) -> Option<Self::Item> {
724        match &mut self.0 {
725            IntoIterRepr::Empty => None,
726            IntoIterRepr::Finite(inner) => inner.next_back(),
727            // hashmaps have arbitary iteration order, so reversing it would not make a difference
728            IntoIterRepr::Map(inner) => inner.next(),
729        }
730    }
731}
snix_eval/value/attrs.rs

snix_eval/value/
attrs.rs
