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Add an Atom::try_static method #238

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Merged
bors-servo merged 1 commit into from
Apr 20, 2021
Merged

Add an Atom::try_static method #238

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6 changes: 6 additions & 0 deletions integration-tests/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -290,6 +290,12 @@ fn test_from_string() {
assert!(Atom::from("camembert".to_owned()) == Atom::from("camembert"));
}

#[test]
fn test_try_static() {
assert!(Atom::try_static("head").is_some());
assert!(Atom::try_static("not in the static table").is_none());
}

#[cfg(all(test, feature = "unstable"))]
#[path = "bench.rs"]
mod bench;
26 changes: 18 additions & 8 deletions src/atom.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -149,6 +149,22 @@ impl<Static: StaticAtomSet> Atom<Static> {
_ => unsafe { debug_unreachable!() },
}
}

pub fn try_static(string_to_add: &str) -> Option<Self> {
Self::try_static_internal(string_to_add).ok()
}

fn try_static_internal(string_to_add: &str) -> Result<Self, phf_shared::Hashes> {
let static_set = Static::get();
let hash = phf_shared::hash(&*string_to_add, &static_set.key);
let index = phf_shared::get_index(&hash, static_set.disps, static_set.atoms.len());

if static_set.atoms[index as usize] == string_to_add {
Ok(Self::pack_static(index))
} else {
Err(hash)
}
}
}

impl<Static: StaticAtomSet> Default for Atom<Static> {
Expand All @@ -170,13 +186,7 @@ impl<Static: StaticAtomSet> Hash for Atom<Static> {

impl<'a, Static: StaticAtomSet> From<Cow<'a, str>> for Atom<Static> {
fn from(string_to_add: Cow<'a, str>) -> Self {
let static_set = Static::get();
let hash = phf_shared::hash(&*string_to_add, &static_set.key);
let index = phf_shared::get_index(&hash, static_set.disps, static_set.atoms.len());

if static_set.atoms[index as usize] == string_to_add {
Self::pack_static(index)
} else {
Self::try_static_internal(&*string_to_add).unwrap_or_else(|hash| {
let len = string_to_add.len();
if len <= MAX_INLINE_LEN {
let mut data: u64 = (INLINE_TAG as u64) | ((len as u64) << LEN_OFFSET);
Expand All @@ -200,7 +210,7 @@ impl<'a, Static: StaticAtomSet> From<Cow<'a, str>> for Atom<Static> {
phantom: PhantomData,
}
}
}
})
}
}

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