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feat(tvix/eval): rm NixContext::join, add take_context & IntoIterator

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In places where we want to extend context with that from another
NixString, use take_context() to split it off, then call .extend(),
making use of IntoIterator to avoid a bunch of clones.

Change-Id: I2460141a3ed776c64c36132b2203b6a1d710b922
Reviewed-on: https://cl.tvl.fyi/c/depot/+/11705
Tested-by: BuildkiteCI
Autosubmit: flokli <flokli@flokli.de>
Reviewed-by: edef <edef@edef.eu>
This commit is contained in:
Florian Klink 2024-05-23 15:10:32 +02:00 • committed by clbot
parent ec8d79f3db
commit 649a862ae1
6 changed files with 57 additions and 60 deletions
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39
tvix/eval/src/value/string.rs
View file

@ -78,15 +78,6 @@ impl NixContext {
self
}
/// Consumes both ends of the join into a new NixContent
/// containing the union of elements of both ends.
pub fn join(mut self, other: &mut NixContext) -> Self {
let other_set = std::mem::take(&mut other.0);
let mut set: HashSet<NixContextElement> = std::mem::take(&mut self.0);
set.extend(other_set);
Self(set)
}
/// Extends the existing context with more context elements.
pub fn extend<T>(&mut self, iter: T)
where
@ -162,6 +153,16 @@ impl NixContext {
}
}
impl IntoIterator for NixContext {
type Item = NixContextElement;
type IntoIter = std::collections::hash_set::IntoIter<NixContextElement>;
fn into_iter(self) -> Self::IntoIter {
self.0.into_iter()
}
}
/// This type is never instantiated, but serves to document the memory layout of the actual heap
/// allocation for Nix strings.
#[allow(dead_code)]
@ -715,8 +716,10 @@ impl NixString {
let context = [self.context(), other.context()]
.into_iter()
.flatten()
.fold(NixContext::new(), |acc_ctx, new_ctx| {
acc_ctx.join(&mut new_ctx.clone())
.fold(NixContext::new(), |mut acc_ctx, new_ctx| {
// TODO: consume new_ctx?
acc_ctx.extend(new_ctx.iter().cloned());
acc_ctx
});
Self::new_context_from(context, s)
}
@ -730,13 +733,13 @@ impl NixString {
unsafe { NixStringInner::context_ref(self.0).as_deref() }
}
pub(crate) fn context_mut(&mut self) -> Option<&mut NixContext> {
pub(crate) fn context_mut(&mut self) -> &mut Option<Box<NixContext>> {
// SAFETY: There's no way to construct an uninitialized or invalid NixString (see the SAFETY
// comment in `new`).
//
// Also, we're using the same lifetime and mutability as self, to fit the
// pointer-to-reference conversion rules
unsafe { NixStringInner::context_mut(self.0).as_deref_mut() }
unsafe { NixStringInner::context_mut(self.0) }
}
pub fn iter_context(&self) -> impl Iterator<Item = &NixContext> {
@ -764,12 +767,16 @@ impl NixString {
self.context().is_some()
}
/// This clears the context of the string, returning
/// the removed dependency tracking information.
pub fn take_context(&mut self) -> Option<Box<NixContext>> {
self.context_mut().take()
}
/// This clears the context of that string, losing
/// all dependency tracking information.
pub fn clear_context(&mut self) {
// SAFETY: There's no way to construct an uninitialized or invalid NixString (see the SAFETY
// comment in `new`).
*unsafe { NixStringInner::context_mut(self.0) } = None;
let _ = self.take_context();
}
pub fn chars(&self) -> Chars<'_> {