}
}
+// Note: all the methods in this trait are infallible, which may be surprising.
+// They used to be fallible (i.e. return a `Result`) but many of the impls just
+// panicked when something went wrong, and for the cases that didn't the
+// top-level invocation would also just panic on failure. Switching to
+// infallibility made things faster and lots of code a little simpler and more
+// concise.
pub trait Decoder {
- type Error;
-
// Primitive types:
- fn read_nil(&mut self) -> Result<(), Self::Error>;
- fn read_usize(&mut self) -> Result<usize, Self::Error>;
- fn read_u128(&mut self) -> Result<u128, Self::Error>;
- fn read_u64(&mut self) -> Result<u64, Self::Error>;
- fn read_u32(&mut self) -> Result<u32, Self::Error>;
- fn read_u16(&mut self) -> Result<u16, Self::Error>;
- fn read_u8(&mut self) -> Result<u8, Self::Error>;
- fn read_isize(&mut self) -> Result<isize, Self::Error>;
- fn read_i128(&mut self) -> Result<i128, Self::Error>;
- fn read_i64(&mut self) -> Result<i64, Self::Error>;
- fn read_i32(&mut self) -> Result<i32, Self::Error>;
- fn read_i16(&mut self) -> Result<i16, Self::Error>;
- fn read_i8(&mut self) -> Result<i8, Self::Error>;
- fn read_bool(&mut self) -> Result<bool, Self::Error>;
- fn read_f64(&mut self) -> Result<f64, Self::Error>;
- fn read_f32(&mut self) -> Result<f32, Self::Error>;
- fn read_char(&mut self) -> Result<char, Self::Error>;
- fn read_str(&mut self) -> Result<Cow<'_, str>, Self::Error>;
- fn read_raw_bytes_into(&mut self, s: &mut [u8]) -> Result<(), Self::Error>;
+ fn read_unit(&mut self) -> ();
+ fn read_usize(&mut self) -> usize;
+ fn read_u128(&mut self) -> u128;
+ fn read_u64(&mut self) -> u64;
+ fn read_u32(&mut self) -> u32;
+ fn read_u16(&mut self) -> u16;
+ fn read_u8(&mut self) -> u8;
+ fn read_isize(&mut self) -> isize;
+ fn read_i128(&mut self) -> i128;
+ fn read_i64(&mut self) -> i64;
+ fn read_i32(&mut self) -> i32;
+ fn read_i16(&mut self) -> i16;
+ fn read_i8(&mut self) -> i8;
+ fn read_bool(&mut self) -> bool;
+ fn read_f64(&mut self) -> f64;
+ fn read_f32(&mut self) -> f32;
+ fn read_char(&mut self) -> char;
+ fn read_str(&mut self) -> Cow<'_, str>;
+ fn read_raw_bytes_into(&mut self, s: &mut [u8]);
- // Compound types:
#[inline]
- fn read_enum<T, F>(&mut self, f: F) -> Result<T, Self::Error>
+ fn read_enum_variant<T, F>(&mut self, mut f: F) -> T
where
- F: FnOnce(&mut Self) -> Result<T, Self::Error>,
+ F: FnMut(&mut Self, usize) -> T,
{
- f(self)
- }
-
- #[inline]
- fn read_enum_variant<T, F>(&mut self, _names: &[&str], mut f: F) -> Result<T, Self::Error>
- where
- F: FnMut(&mut Self, usize) -> Result<T, Self::Error>,
- {
- let disr = self.read_usize()?;
+ let disr = self.read_usize();
f(self, disr)
}
#[inline]
- fn read_enum_variant_arg<T, F>(&mut self, f: F) -> Result<T, Self::Error>
- where
- F: FnOnce(&mut Self) -> Result<T, Self::Error>,
- {
- f(self)
- }
-
- #[inline]
- fn read_struct<T, F>(&mut self, f: F) -> Result<T, Self::Error>
- where
- F: FnOnce(&mut Self) -> Result<T, Self::Error>,
- {
- f(self)
- }
-
- #[inline]
- fn read_struct_field<T, F>(&mut self, _f_name: &str, f: F) -> Result<T, Self::Error>
+ fn read_tuple_arg<T, F>(&mut self, f: F) -> T
where
- F: FnOnce(&mut Self) -> Result<T, Self::Error>,
- {
- f(self)
- }
-
- #[inline]
- fn read_tuple<T, F>(&mut self, _len: usize, f: F) -> Result<T, Self::Error>
- where
- F: FnOnce(&mut Self) -> Result<T, Self::Error>,
- {
- f(self)
- }
-
- #[inline]
- fn read_tuple_arg<T, F>(&mut self, f: F) -> Result<T, Self::Error>
- where
- F: FnOnce(&mut Self) -> Result<T, Self::Error>,
+ F: FnOnce(&mut Self) -> T,
{
f(self)
}
// Specialized types:
- fn read_option<T, F>(&mut self, mut f: F) -> Result<T, Self::Error>
+ fn read_option<T, F>(&mut self, mut f: F) -> T
where
- F: FnMut(&mut Self, bool) -> Result<T, Self::Error>,
+ F: FnMut(&mut Self, bool) -> T,
{
- self.read_enum(move |this| {
- this.read_enum_variant(&["None", "Some"], move |this, idx| match idx {
- 0 => f(this, false),
- 1 => f(this, true),
- _ => Err(this.error("read_option: expected 0 for None or 1 for Some")),
- })
+ self.read_enum_variant(move |this, idx| match idx {
+ 0 => f(this, false),
+ 1 => f(this, true),
+ _ => panic!("read_option: expected 0 for None or 1 for Some"),
})
}
- fn read_seq<T, F>(&mut self, f: F) -> Result<T, Self::Error>
+ fn read_seq<T, F>(&mut self, f: F) -> T
where
- F: FnOnce(&mut Self, usize) -> Result<T, Self::Error>,
+ F: FnOnce(&mut Self, usize) -> T,
{
- let len = self.read_usize()?;
+ let len = self.read_usize();
f(self, len)
}
#[inline]
- fn read_seq_elt<T, F>(&mut self, f: F) -> Result<T, Self::Error>
+ fn read_seq_elt<T, F>(&mut self, f: F) -> T
where
- F: FnOnce(&mut Self) -> Result<T, Self::Error>,
+ F: FnOnce(&mut Self) -> T,
{
f(self)
}
- fn read_map<T, F>(&mut self, f: F) -> Result<T, Self::Error>
+ fn read_map<T, F>(&mut self, f: F) -> T
where
- F: FnOnce(&mut Self, usize) -> Result<T, Self::Error>,
+ F: FnOnce(&mut Self, usize) -> T,
{
- let len = self.read_usize()?;
+ let len = self.read_usize();
f(self, len)
}
#[inline]
- fn read_map_elt_key<T, F>(&mut self, f: F) -> Result<T, Self::Error>
+ fn read_map_elt_key<T, F>(&mut self, f: F) -> T
where
- F: FnOnce(&mut Self) -> Result<T, Self::Error>,
+ F: FnOnce(&mut Self) -> T,
{
f(self)
}
#[inline]
- fn read_map_elt_val<T, F>(&mut self, f: F) -> Result<T, Self::Error>
+ fn read_map_elt_val<T, F>(&mut self, f: F) -> T
where
- F: FnOnce(&mut Self) -> Result<T, Self::Error>,
+ F: FnOnce(&mut Self) -> T,
{
f(self)
}
-
- // Failure
- fn error(&mut self, err: &str) -> Self::Error;
}
/// Trait for types that can be serialized
/// * `TyDecodable` should be used for types that are only serialized in crate
/// metadata or the incremental cache. This is most types in `rustc_middle`.
pub trait Decodable<D: Decoder>: Sized {
- fn decode(d: &mut D) -> Result<Self, D::Error>;
+ fn decode(d: &mut D) -> Self;
}
macro_rules! direct_serialize_impls {
}
impl<D: Decoder> Decodable<D> for $ty {
- fn decode(d: &mut D) -> Result<$ty, D::Error> {
+ fn decode(d: &mut D) -> $ty {
d.$read_method()
}
}
}
impl<D: Decoder> Decodable<D> for ! {
- fn decode(_d: &mut D) -> Result<!, D::Error> {
+ fn decode(_d: &mut D) -> ! {
unreachable!()
}
}
}
impl<D: Decoder> Decodable<D> for ::std::num::NonZeroU32 {
- fn decode(d: &mut D) -> Result<Self, D::Error> {
- d.read_u32().map(|d| ::std::num::NonZeroU32::new(d).unwrap())
+ fn decode(d: &mut D) -> Self {
+ ::std::num::NonZeroU32::new(d.read_u32()).unwrap()
}
}
}
impl<D: Decoder> Decodable<D> for String {
- fn decode(d: &mut D) -> Result<String, D::Error> {
- Ok(d.read_str()?.into_owned())
+ fn decode(d: &mut D) -> String {
+ d.read_str().into_owned()
}
}
}
impl<D: Decoder> Decodable<D> for () {
- fn decode(d: &mut D) -> Result<(), D::Error> {
- d.read_nil()
+ fn decode(d: &mut D) -> () {
+ d.read_unit()
}
}
}
impl<D: Decoder, T> Decodable<D> for PhantomData<T> {
- fn decode(d: &mut D) -> Result<PhantomData<T>, D::Error> {
- d.read_nil()?;
- Ok(PhantomData)
+ fn decode(d: &mut D) -> PhantomData<T> {
+ d.read_unit();
+ PhantomData
}
}
impl<D: Decoder, T: Decodable<D>> Decodable<D> for Box<[T]> {
- fn decode(d: &mut D) -> Result<Box<[T]>, D::Error> {
- let v: Vec<T> = Decodable::decode(d)?;
- Ok(v.into_boxed_slice())
+ fn decode(d: &mut D) -> Box<[T]> {
+ let v: Vec<T> = Decodable::decode(d);
+ v.into_boxed_slice()
}
}
}
impl<D: Decoder, T: Decodable<D>> Decodable<D> for Rc<T> {
- fn decode(d: &mut D) -> Result<Rc<T>, D::Error> {
- Ok(Rc::new(Decodable::decode(d)?))
+ fn decode(d: &mut D) -> Rc<T> {
+ Rc::new(Decodable::decode(d))
}
}
}
impl<D: Decoder, T: Decodable<D>> Decodable<D> for Vec<T> {
- default fn decode(d: &mut D) -> Result<Vec<T>, D::Error> {
+ default fn decode(d: &mut D) -> Vec<T> {
d.read_seq(|d, len| {
- let mut v = Vec::with_capacity(len);
- for _ in 0..len {
- v.push(d.read_seq_elt(|d| Decodable::decode(d))?);
+ // SAFETY: we set the capacity in advance, only write elements, and
+ // only set the length at the end once the writing has succeeded.
+ let mut vec = Vec::with_capacity(len);
+ unsafe {
+ let ptr: *mut T = vec.as_mut_ptr();
+ for i in 0..len {
+ std::ptr::write(
+ ptr.offset(i as isize),
+ d.read_seq_elt(|d| Decodable::decode(d)),
+ );
+ }
+ vec.set_len(len);
}
- Ok(v)
+ vec
})
}
}
}
impl<D: Decoder, const N: usize> Decodable<D> for [u8; N] {
- fn decode(d: &mut D) -> Result<[u8; N], D::Error> {
+ fn decode(d: &mut D) -> [u8; N] {
d.read_seq(|d, len| {
assert!(len == N);
let mut v = [0u8; N];
for i in 0..len {
- v[i] = d.read_seq_elt(|d| Decodable::decode(d))?;
+ v[i] = d.read_seq_elt(|d| Decodable::decode(d));
}
- Ok(v)
+ v
})
}
}
where
[T]: ToOwned<Owned = Vec<T>>,
{
- fn decode(d: &mut D) -> Result<Cow<'static, [T]>, D::Error> {
- let v: Vec<T> = Decodable::decode(d)?;
- Ok(Cow::Owned(v))
+ fn decode(d: &mut D) -> Cow<'static, [T]> {
+ let v: Vec<T> = Decodable::decode(d);
+ Cow::Owned(v)
}
}
}
impl<D: Decoder, T: Decodable<D>> Decodable<D> for Option<T> {
- fn decode(d: &mut D) -> Result<Option<T>, D::Error> {
- d.read_option(|d, b| if b { Ok(Some(Decodable::decode(d)?)) } else { Ok(None) })
+ fn decode(d: &mut D) -> Option<T> {
+ d.read_option(|d, b| if b { Some(Decodable::decode(d)) } else { None })
}
}
}
impl<D: Decoder, T1: Decodable<D>, T2: Decodable<D>> Decodable<D> for Result<T1, T2> {
- fn decode(d: &mut D) -> Result<Result<T1, T2>, D::Error> {
- d.read_enum(|d| {
- d.read_enum_variant(&["Ok", "Err"], |d, disr| match disr {
- 0 => Ok(Ok(d.read_enum_variant_arg(|d| T1::decode(d))?)),
- 1 => Ok(Err(d.read_enum_variant_arg(|d| T2::decode(d))?)),
- _ => {
- panic!(
- "Encountered invalid discriminant while \
- decoding `Result`."
- );
- }
- })
+ fn decode(d: &mut D) -> Result<T1, T2> {
+ d.read_enum_variant(|d, disr| match disr {
+ 0 => Ok(T1::decode(d)),
+ 1 => Err(T2::decode(d)),
+ _ => panic!("Encountered invalid discriminant while decoding `Result`."),
})
}
}
( $($name:ident,)+ ) => (
impl<D: Decoder, $($name: Decodable<D>),+> Decodable<D> for ($($name,)+) {
#[allow(non_snake_case)]
- fn decode(d: &mut D) -> Result<($($name,)+), D::Error> {
- let len: usize = count!($($name)+);
- d.read_tuple(len, |d| {
- let ret = ($(d.read_tuple_arg(|d| -> Result<$name, D::Error> {
- Decodable::decode(d)
- })?,)+);
- Ok(ret)
- })
+ fn decode(d: &mut D) -> ($($name,)+) {
+ ($(d.read_tuple_arg(|d| -> $name {
+ Decodable::decode(d)
+ }),)+)
}
}
impl<S: Encoder, $($name: Encodable<S>),+> Encodable<S> for ($($name,)+) {
#[allow(non_snake_case)]
fn encode(&self, s: &mut S) -> Result<(), S::Error> {
let ($(ref $name,)+) = *self;
- let mut n = 0;
- $(let $name = $name; n += 1;)+
- s.emit_tuple(n, |s| {
+ let len: usize = count!($($name)+);
+ s.emit_tuple(len, |s| {
let mut i = 0;
$(s.emit_tuple_arg({ i+=1; i-1 }, |s| $name.encode(s))?;)+
Ok(())
}
impl<D: Decoder> Decodable<D> for path::PathBuf {
- fn decode(d: &mut D) -> Result<path::PathBuf, D::Error> {
- let bytes: String = Decodable::decode(d)?;
- Ok(path::PathBuf::from(bytes))
+ fn decode(d: &mut D) -> path::PathBuf {
+ let bytes: String = Decodable::decode(d);
+ path::PathBuf::from(bytes)
}
}
}
impl<D: Decoder, T: Decodable<D> + Copy> Decodable<D> for Cell<T> {
- fn decode(d: &mut D) -> Result<Cell<T>, D::Error> {
- Ok(Cell::new(Decodable::decode(d)?))
+ fn decode(d: &mut D) -> Cell<T> {
+ Cell::new(Decodable::decode(d))
}
}
}
impl<D: Decoder, T: Decodable<D>> Decodable<D> for RefCell<T> {
- fn decode(d: &mut D) -> Result<RefCell<T>, D::Error> {
- Ok(RefCell::new(Decodable::decode(d)?))
+ fn decode(d: &mut D) -> RefCell<T> {
+ RefCell::new(Decodable::decode(d))
}
}
}
impl<D: Decoder, T: Decodable<D>> Decodable<D> for Arc<T> {
- fn decode(d: &mut D) -> Result<Arc<T>, D::Error> {
- Ok(Arc::new(Decodable::decode(d)?))
+ fn decode(d: &mut D) -> Arc<T> {
+ Arc::new(Decodable::decode(d))
}
}
}
}
impl<D: Decoder, T: Decodable<D>> Decodable<D> for Box<T> {
- fn decode(d: &mut D) -> Result<Box<T>, D::Error> {
- Ok(Box::new(Decodable::decode(d)?))
+ fn decode(d: &mut D) -> Box<T> {
+ Box::new(Decodable::decode(d))
}
}
projects / rust.git / blobdiff