Vendor things

third-party/vendor/phf_shared/src/lib.rs

@@ -0,0 +1,421 @@
+#![doc(html_root_url = "https://docs.rs/phf_shared/0.9")]
+#![cfg_attr(not(feature = "std"), no_std)]
+
+#[cfg(feature = "std")]
+extern crate std as core;
+
+use core::fmt;
+use core::hash::{Hash, Hasher};
+use core::num::Wrapping;
+use siphasher::sip128::{Hash128, Hasher128, SipHasher13};
+
+#[non_exhaustive]
+pub struct Hashes {
+    pub g: u32,
+    pub f1: u32,
+    pub f2: u32,
+}
+
+/// A central typedef for hash keys
+///
+/// Makes experimentation easier by only needing to be updated here.
+pub type HashKey = u64;
+
+#[inline]
+pub fn displace(f1: u32, f2: u32, d1: u32, d2: u32) -> u32 {
+    (Wrapping(d2) + Wrapping(f1) * Wrapping(d1) + Wrapping(f2)).0
+}
+
+/// `key` is from `phf_generator::HashState`.
+#[inline]
+pub fn hash<T: ?Sized + PhfHash>(x: &T, key: &HashKey) -> Hashes {
+    let mut hasher = SipHasher13::new_with_keys(0, *key);
+    x.phf_hash(&mut hasher);
+
+    let Hash128 {
+        h1: lower,
+        h2: upper,
+    } = hasher.finish128();
+
+    Hashes {
+        g: (lower >> 32) as u32,
+        f1: lower as u32,
+        f2: upper as u32,
+    }
+}
+
+/// Return an index into `phf_generator::HashState::map`.
+///
+/// * `hash` is from `hash()` in this crate.
+/// * `disps` is from `phf_generator::HashState::disps`.
+/// * `len` is the length of `phf_generator::HashState::map`.
+#[inline]
+pub fn get_index(hashes: &Hashes, disps: &[(u32, u32)], len: usize) -> u32 {
+    let (d1, d2) = disps[(hashes.g % (disps.len() as u32)) as usize];
+    displace(hashes.f1, hashes.f2, d1, d2) % (len as u32)
+}
+
+/// A trait implemented by types which can be used in PHF data structures.
+///
+/// This differs from the standard library's `Hash` trait in that `PhfHash`'s
+/// results must be architecture independent so that hashes will be consistent
+/// between the host and target when cross compiling.
+pub trait PhfHash {
+    /// Feeds the value into the state given, updating the hasher as necessary.
+    fn phf_hash<H: Hasher>(&self, state: &mut H);
+
+    /// Feeds a slice of this type into the state provided.
+    fn phf_hash_slice<H: Hasher>(data: &[Self], state: &mut H)
+    where
+        Self: Sized,
+    {
+        for piece in data {
+            piece.phf_hash(state);
+        }
+    }
+}
+
+/// Trait for printing types with `const` constructors, used by `phf_codegen` and `phf_macros`.
+pub trait FmtConst {
+    /// Print a `const` expression representing this value.
+    fn fmt_const(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result;
+}
+
+/// Identical to `std::borrow::Borrow` except omitting blanket impls to facilitate other
+/// borrowing patterns.
+///
+/// The same semantic requirements apply:
+///
+/// > In particular `Eq`, `Ord` and `Hash` must be equivalent for borrowed and owned values:
+/// `x.borrow() == y.borrow()` should give the same result as `x == y`.
+///
+/// (This crate's API only requires `Eq` and `PhfHash`, however.)
+///
+/// ### Motivation
+/// The conventional signature for lookup methods on collections looks something like this:
+///
+/// ```rust,ignore
+/// impl<K, V> Map<K, V> where K: PhfHash + Eq {
+///     fn get<T: ?Sized>(&self, key: &T) -> Option<&V> where T: PhfHash + Eq, K: Borrow<T> {
+///         ...
+///     }
+/// }
+/// ```
+///
+/// This allows the key type used for lookup to be different than the key stored in the map so for
+/// example you can use `&str` to look up a value in a `Map<String, _>`. However, this runs into
+/// a problem in the case where `T` and `K` are both a `Foo<_>` type constructor but
+/// the contained type is different (even being the same type with different lifetimes).
+///
+/// The main issue for this crate's API is that, with this method signature, you cannot perform a
+/// lookup on a `Map<UniCase<&'static str>, _>` with a `UniCase<&'a str>` where `'a` is not
+/// `'static`; there is no impl of `Borrow` that resolves to
+/// `impl Borrow<UniCase<'a>> for UniCase<&'static str>` and one cannot be added either because of
+/// all the blanket impls.
+///
+/// Instead, this trait is implemented conservatively, without blanket impls, so that impls like
+/// this may be added. This is feasible since the set of types that implement `PhfHash` is
+/// intentionally small.
+///
+/// This likely won't be fixable with specialization alone but will require full support for lattice
+/// impls since we technically want to add overlapping blanket impls.
+pub trait PhfBorrow<B: ?Sized> {
+    /// Convert a reference to `self` to a reference to the borrowed type.
+    fn borrow(&self) -> &B;
+}
+
+/// Create an impl of `FmtConst` delegating to `fmt::Debug` for types that can deal with it.
+///
+/// Ideally with specialization this could be just one default impl and then specialized where
+/// it doesn't apply.
+macro_rules! delegate_debug (
+    ($ty:ty) => {
+        impl FmtConst for $ty {
+            fn fmt_const(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+                write!(f, "{:?}", self)
+            }
+        }
+    }
+);
+
+delegate_debug!(str);
+delegate_debug!(char);
+delegate_debug!(u8);
+delegate_debug!(i8);
+delegate_debug!(u16);
+delegate_debug!(i16);
+delegate_debug!(u32);
+delegate_debug!(i32);
+delegate_debug!(u64);
+delegate_debug!(i64);
+delegate_debug!(u128);
+delegate_debug!(i128);
+delegate_debug!(bool);
+
+/// `impl PhfBorrow<T> for T`
+macro_rules! impl_reflexive(
+    ($($t:ty),*) => (
+        $(impl PhfBorrow<$t> for $t {
+            fn borrow(&self) -> &$t {
+                self
+            }
+        })*
+    )
+);
+
+impl_reflexive!(
+    str,
+    char,
+    u8,
+    i8,
+    u16,
+    i16,
+    u32,
+    i32,
+    u64,
+    i64,
+    u128,
+    i128,
+    bool,
+    [u8]
+);
+
+#[cfg(feature = "std")]
+impl PhfBorrow<str> for String {
+    fn borrow(&self) -> &str {
+        self
+    }
+}
+
+#[cfg(feature = "std")]
+impl PhfBorrow<[u8]> for Vec<u8> {
+    fn borrow(&self) -> &[u8] {
+        self
+    }
+}
+
+#[cfg(feature = "std")]
+delegate_debug!(String);
+
+#[cfg(feature = "std")]
+impl PhfHash for String {
+    #[inline]
+    fn phf_hash<H: Hasher>(&self, state: &mut H) {
+        (**self).phf_hash(state)
+    }
+}
+
+#[cfg(feature = "std")]
+impl PhfHash for Vec<u8> {
+    #[inline]
+    fn phf_hash<H: Hasher>(&self, state: &mut H) {
+        (**self).phf_hash(state)
+    }
+}
+
+impl<'a, T: 'a + PhfHash + ?Sized> PhfHash for &'a T {
+    fn phf_hash<H: Hasher>(&self, state: &mut H) {
+        (*self).phf_hash(state)
+    }
+}
+
+impl<'a, T: 'a + FmtConst + ?Sized> FmtConst for &'a T {
+    fn fmt_const(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        (*self).fmt_const(f)
+    }
+}
+
+impl<'a> PhfBorrow<str> for &'a str {
+    fn borrow(&self) -> &str {
+        self
+    }
+}
+
+impl<'a> PhfBorrow<[u8]> for &'a [u8] {
+    fn borrow(&self) -> &[u8] {
+        self
+    }
+}
+
+impl PhfHash for str {
+    #[inline]
+    fn phf_hash<H: Hasher>(&self, state: &mut H) {
+        self.as_bytes().phf_hash(state)
+    }
+}
+
+impl PhfHash for [u8] {
+    #[inline]
+    fn phf_hash<H: Hasher>(&self, state: &mut H) {
+        state.write(self);
+    }
+}
+
+impl FmtConst for [u8] {
+    #[inline]
+    fn fmt_const(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        // slices need a leading reference
+        write!(f, "&{:?}", self)
+    }
+}
+
+#[cfg(feature = "unicase")]
+impl<S> PhfHash for unicase::UniCase<S>
+where
+    unicase::UniCase<S>: Hash,
+{
+    #[inline]
+    fn phf_hash<H: Hasher>(&self, state: &mut H) {
+        self.hash(state)
+    }
+}
+
+#[cfg(feature = "unicase")]
+impl<S> FmtConst for unicase::UniCase<S>
+where
+    S: AsRef<str>,
+{
+    fn fmt_const(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        if self.is_ascii() {
+            f.write_str("UniCase::ascii(")?;
+        } else {
+            f.write_str("UniCase::unicode(")?;
+        }
+
+        self.as_ref().fmt_const(f)?;
+        f.write_str(")")
+    }
+}
+
+#[cfg(feature = "unicase")]
+impl<'b, 'a: 'b, S: ?Sized + 'a> PhfBorrow<unicase::UniCase<&'b S>> for unicase::UniCase<&'a S> {
+    fn borrow(&self) -> &unicase::UniCase<&'b S> {
+        self
+    }
+}
+
+#[cfg(feature = "uncased")]
+impl PhfHash for uncased::UncasedStr {
+    #[inline]
+    fn phf_hash<H: Hasher>(&self, state: &mut H) {
+        self.hash(state)
+    }
+}
+
+#[cfg(feature = "uncased")]
+impl FmtConst for uncased::UncasedStr {
+    fn fmt_const(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        // transmute is not stable in const fns (rust-lang/rust#53605), so
+        // `UncasedStr::new` can't be a const fn itself, but we can inline the
+        // call to transmute here in the meantime.
+        f.write_str("unsafe { ::std::mem::transmute::<&'static str, &'static UncasedStr>(")?;
+        self.as_str().fmt_const(f)?;
+        f.write_str(") }")
+    }
+}
+
+#[cfg(feature = "uncased")]
+impl PhfBorrow<uncased::UncasedStr> for &uncased::UncasedStr {
+    fn borrow(&self) -> &uncased::UncasedStr {
+        self
+    }
+}
+
+macro_rules! sip_impl (
+    (le $t:ty) => (
+        impl PhfHash for $t {
+            #[inline]
+            fn phf_hash<H: Hasher>(&self, state: &mut H) {
+                self.to_le().hash(state);
+            }
+        }
+    );
+    ($t:ty) => (
+        impl PhfHash for $t {
+            #[inline]
+            fn phf_hash<H: Hasher>(&self, state: &mut H) {
+                self.hash(state);
+            }
+        }
+    )
+);
+
+sip_impl!(u8);
+sip_impl!(i8);
+sip_impl!(le u16);
+sip_impl!(le i16);
+sip_impl!(le u32);
+sip_impl!(le i32);
+sip_impl!(le u64);
+sip_impl!(le i64);
+sip_impl!(le u128);
+sip_impl!(le i128);
+sip_impl!(bool);
+
+impl PhfHash for char {
+    #[inline]
+    fn phf_hash<H: Hasher>(&self, state: &mut H) {
+        (*self as u32).phf_hash(state)
+    }
+}
+
+// minimize duplicated code since formatting drags in quite a bit
+fn fmt_array(array: &[u8], f: &mut fmt::Formatter<'_>) -> fmt::Result {
+    write!(f, "{:?}", array)
+}
+
+macro_rules! array_impl (
+    ($t:ty, $n:expr) => (
+        impl PhfHash for [$t; $n] {
+            #[inline]
+            fn phf_hash<H: Hasher>(&self, state: &mut H) {
+                state.write(self);
+            }
+        }
+
+        impl FmtConst for [$t; $n] {
+            fn fmt_const(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt_array(self, f)
+            }
+        }
+
+        impl PhfBorrow<[$t]> for [$t; $n] {
+            fn borrow(&self) -> &[$t] {
+                self
+            }
+        }
+    )
+);
+
+array_impl!(u8, 1);
+array_impl!(u8, 2);
+array_impl!(u8, 3);
+array_impl!(u8, 4);
+array_impl!(u8, 5);
+array_impl!(u8, 6);
+array_impl!(u8, 7);
+array_impl!(u8, 8);
+array_impl!(u8, 9);
+array_impl!(u8, 10);
+array_impl!(u8, 11);
+array_impl!(u8, 12);
+array_impl!(u8, 13);
+array_impl!(u8, 14);
+array_impl!(u8, 15);
+array_impl!(u8, 16);
+array_impl!(u8, 17);
+array_impl!(u8, 18);
+array_impl!(u8, 19);
+array_impl!(u8, 20);
+array_impl!(u8, 21);
+array_impl!(u8, 22);
+array_impl!(u8, 23);
+array_impl!(u8, 24);
+array_impl!(u8, 25);
+array_impl!(u8, 26);
+array_impl!(u8, 27);
+array_impl!(u8, 28);
+array_impl!(u8, 29);
+array_impl!(u8, 30);
+array_impl!(u8, 31);
+array_impl!(u8, 32);