1 //! Support code for encoding and decoding types.
4 Core encoding and decoding interfaces.
8 use std::cell::{Cell, RefCell};
9 use std::marker::PhantomData;
18 fn emit_unit(&mut self) -> Result<(), Self::Error>;
19 fn emit_usize(&mut self, v: usize) -> Result<(), Self::Error>;
20 fn emit_u128(&mut self, v: u128) -> Result<(), Self::Error>;
21 fn emit_u64(&mut self, v: u64) -> Result<(), Self::Error>;
22 fn emit_u32(&mut self, v: u32) -> Result<(), Self::Error>;
23 fn emit_u16(&mut self, v: u16) -> Result<(), Self::Error>;
24 fn emit_u8(&mut self, v: u8) -> Result<(), Self::Error>;
25 fn emit_isize(&mut self, v: isize) -> Result<(), Self::Error>;
26 fn emit_i128(&mut self, v: i128) -> Result<(), Self::Error>;
27 fn emit_i64(&mut self, v: i64) -> Result<(), Self::Error>;
28 fn emit_i32(&mut self, v: i32) -> Result<(), Self::Error>;
29 fn emit_i16(&mut self, v: i16) -> Result<(), Self::Error>;
30 fn emit_i8(&mut self, v: i8) -> Result<(), Self::Error>;
31 fn emit_bool(&mut self, v: bool) -> Result<(), Self::Error>;
32 fn emit_f64(&mut self, v: f64) -> Result<(), Self::Error>;
33 fn emit_f32(&mut self, v: f32) -> Result<(), Self::Error>;
34 fn emit_char(&mut self, v: char) -> Result<(), Self::Error>;
35 fn emit_str(&mut self, v: &str) -> Result<(), Self::Error>;
36 fn emit_raw_bytes(&mut self, s: &[u8]) -> Result<(), Self::Error>;
40 fn emit_enum<F>(&mut self, f: F) -> Result<(), Self::Error>
42 F: FnOnce(&mut Self) -> Result<(), Self::Error>,
47 fn emit_enum_variant<F>(
53 ) -> Result<(), Self::Error>
55 F: FnOnce(&mut Self) -> Result<(), Self::Error>,
57 self.emit_usize(v_id)?;
61 // We put the field index in a const generic to allow the emit_usize to be
62 // compiled into a more efficient form. In practice, the variant index is
63 // known at compile-time, and that knowledge allows much more efficient
64 // codegen than we'd otherwise get. LLVM isn't always able to make the
65 // optimization that would otherwise be necessary here, likely due to the
66 // multiple levels of inlining and const-prop that are needed.
68 fn emit_fieldless_enum_variant<const ID: usize>(
71 ) -> Result<(), Self::Error> {
76 fn emit_enum_variant_arg<F>(&mut self, _first: bool, f: F) -> Result<(), Self::Error>
78 F: FnOnce(&mut Self) -> Result<(), Self::Error>,
84 fn emit_struct<F>(&mut self, _no_fields: bool, f: F) -> Result<(), Self::Error>
86 F: FnOnce(&mut Self) -> Result<(), Self::Error>,
92 fn emit_struct_field<F>(&mut self, _f_name: &str, _first: bool, f: F) -> Result<(), Self::Error>
94 F: FnOnce(&mut Self) -> Result<(), Self::Error>,
100 fn emit_tuple<F>(&mut self, _len: usize, f: F) -> Result<(), Self::Error>
102 F: FnOnce(&mut Self) -> Result<(), Self::Error>,
108 fn emit_tuple_arg<F>(&mut self, _idx: usize, f: F) -> Result<(), Self::Error>
110 F: FnOnce(&mut Self) -> Result<(), Self::Error>,
115 // Specialized types:
116 fn emit_option<F>(&mut self, f: F) -> Result<(), Self::Error>
118 F: FnOnce(&mut Self) -> Result<(), Self::Error>,
124 fn emit_option_none(&mut self) -> Result<(), Self::Error> {
125 self.emit_enum_variant("None", 0, 0, |_| Ok(()))
128 fn emit_option_some<F>(&mut self, f: F) -> Result<(), Self::Error>
130 F: FnOnce(&mut Self) -> Result<(), Self::Error>,
132 self.emit_enum_variant("Some", 1, 1, f)
135 fn emit_seq<F>(&mut self, len: usize, f: F) -> Result<(), Self::Error>
137 F: FnOnce(&mut Self) -> Result<(), Self::Error>,
139 self.emit_usize(len)?;
144 fn emit_seq_elt<F>(&mut self, _idx: usize, f: F) -> Result<(), Self::Error>
146 F: FnOnce(&mut Self) -> Result<(), Self::Error>,
151 fn emit_map<F>(&mut self, len: usize, f: F) -> Result<(), Self::Error>
153 F: FnOnce(&mut Self) -> Result<(), Self::Error>,
155 self.emit_usize(len)?;
160 fn emit_map_elt_key<F>(&mut self, _idx: usize, f: F) -> Result<(), Self::Error>
162 F: FnOnce(&mut Self) -> Result<(), Self::Error>,
168 fn emit_map_elt_val<F>(&mut self, f: F) -> Result<(), Self::Error>
170 F: FnOnce(&mut Self) -> Result<(), Self::Error>,
180 fn read_nil(&mut self) -> Result<(), Self::Error>;
181 fn read_usize(&mut self) -> Result<usize, Self::Error>;
182 fn read_u128(&mut self) -> Result<u128, Self::Error>;
183 fn read_u64(&mut self) -> Result<u64, Self::Error>;
184 fn read_u32(&mut self) -> Result<u32, Self::Error>;
185 fn read_u16(&mut self) -> Result<u16, Self::Error>;
186 fn read_u8(&mut self) -> Result<u8, Self::Error>;
187 fn read_isize(&mut self) -> Result<isize, Self::Error>;
188 fn read_i128(&mut self) -> Result<i128, Self::Error>;
189 fn read_i64(&mut self) -> Result<i64, Self::Error>;
190 fn read_i32(&mut self) -> Result<i32, Self::Error>;
191 fn read_i16(&mut self) -> Result<i16, Self::Error>;
192 fn read_i8(&mut self) -> Result<i8, Self::Error>;
193 fn read_bool(&mut self) -> Result<bool, Self::Error>;
194 fn read_f64(&mut self) -> Result<f64, Self::Error>;
195 fn read_f32(&mut self) -> Result<f32, Self::Error>;
196 fn read_char(&mut self) -> Result<char, Self::Error>;
197 fn read_str(&mut self) -> Result<Cow<'_, str>, Self::Error>;
198 fn read_raw_bytes_into(&mut self, s: &mut [u8]) -> Result<(), Self::Error>;
202 fn read_enum<T, F>(&mut self, f: F) -> Result<T, Self::Error>
204 F: FnOnce(&mut Self) -> Result<T, Self::Error>,
210 fn read_enum_variant<T, F>(&mut self, _names: &[&str], mut f: F) -> Result<T, Self::Error>
212 F: FnMut(&mut Self, usize) -> Result<T, Self::Error>,
214 let disr = self.read_usize()?;
219 fn read_enum_variant_arg<T, F>(&mut self, f: F) -> Result<T, Self::Error>
221 F: FnOnce(&mut Self) -> Result<T, Self::Error>,
227 fn read_struct<T, F>(&mut self, f: F) -> Result<T, Self::Error>
229 F: FnOnce(&mut Self) -> Result<T, Self::Error>,
235 fn read_struct_field<T, F>(&mut self, _f_name: &str, f: F) -> Result<T, Self::Error>
237 F: FnOnce(&mut Self) -> Result<T, Self::Error>,
243 fn read_tuple<T, F>(&mut self, _len: usize, f: F) -> Result<T, Self::Error>
245 F: FnOnce(&mut Self) -> Result<T, Self::Error>,
251 fn read_tuple_arg<T, F>(&mut self, f: F) -> Result<T, Self::Error>
253 F: FnOnce(&mut Self) -> Result<T, Self::Error>,
258 // Specialized types:
259 fn read_option<T, F>(&mut self, mut f: F) -> Result<T, Self::Error>
261 F: FnMut(&mut Self, bool) -> Result<T, Self::Error>,
263 self.read_enum(move |this| {
264 this.read_enum_variant(&["None", "Some"], move |this, idx| match idx {
267 _ => Err(this.error("read_option: expected 0 for None or 1 for Some")),
272 fn read_seq<T, F>(&mut self, f: F) -> Result<T, Self::Error>
274 F: FnOnce(&mut Self, usize) -> Result<T, Self::Error>,
276 let len = self.read_usize()?;
281 fn read_seq_elt<T, F>(&mut self, f: F) -> Result<T, Self::Error>
283 F: FnOnce(&mut Self) -> Result<T, Self::Error>,
288 fn read_map<T, F>(&mut self, f: F) -> Result<T, Self::Error>
290 F: FnOnce(&mut Self, usize) -> Result<T, Self::Error>,
292 let len = self.read_usize()?;
297 fn read_map_elt_key<T, F>(&mut self, f: F) -> Result<T, Self::Error>
299 F: FnOnce(&mut Self) -> Result<T, Self::Error>,
305 fn read_map_elt_val<T, F>(&mut self, f: F) -> Result<T, Self::Error>
307 F: FnOnce(&mut Self) -> Result<T, Self::Error>,
313 fn error(&mut self, err: &str) -> Self::Error;
316 /// Trait for types that can be serialized
318 /// This can be implemented using the `Encodable`, `TyEncodable` and
319 /// `MetadataEncodable` macros.
321 /// * `Encodable` should be used in crates that don't depend on
323 /// * `MetadataEncodable` is used in `rustc_metadata` for types that contain
324 /// `rustc_metadata::rmeta::Lazy`.
325 /// * `TyEncodable` should be used for types that are only serialized in crate
326 /// metadata or the incremental cache. This is most types in `rustc_middle`.
327 pub trait Encodable<S: Encoder> {
328 fn encode(&self, s: &mut S) -> Result<(), S::Error>;
331 /// Trait for types that can be deserialized
333 /// This can be implemented using the `Decodable`, `TyDecodable` and
334 /// `MetadataDecodable` macros.
336 /// * `Decodable` should be used in crates that don't depend on
338 /// * `MetadataDecodable` is used in `rustc_metadata` for types that contain
339 /// `rustc_metadata::rmeta::Lazy`.
340 /// * `TyDecodable` should be used for types that are only serialized in crate
341 /// metadata or the incremental cache. This is most types in `rustc_middle`.
342 pub trait Decodable<D: Decoder>: Sized {
343 fn decode(d: &mut D) -> Result<Self, D::Error>;
346 macro_rules! direct_serialize_impls {
347 ($($ty:ident $emit_method:ident $read_method:ident),*) => {
349 impl<S: Encoder> Encodable<S> for $ty {
350 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
351 s.$emit_method(*self)
355 impl<D: Decoder> Decodable<D> for $ty {
356 fn decode(d: &mut D) -> Result<$ty, D::Error> {
364 direct_serialize_impls! {
365 usize emit_usize read_usize,
367 u16 emit_u16 read_u16,
368 u32 emit_u32 read_u32,
369 u64 emit_u64 read_u64,
370 u128 emit_u128 read_u128,
371 isize emit_isize read_isize,
373 i16 emit_i16 read_i16,
374 i32 emit_i32 read_i32,
375 i64 emit_i64 read_i64,
376 i128 emit_i128 read_i128,
377 f32 emit_f32 read_f32,
378 f64 emit_f64 read_f64,
379 bool emit_bool read_bool,
380 char emit_char read_char
383 impl<S: Encoder> Encodable<S> for ! {
384 fn encode(&self, _s: &mut S) -> Result<(), S::Error> {
389 impl<D: Decoder> Decodable<D> for ! {
390 fn decode(_d: &mut D) -> Result<!, D::Error> {
395 impl<S: Encoder> Encodable<S> for ::std::num::NonZeroU32 {
396 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
397 s.emit_u32(self.get())
401 impl<D: Decoder> Decodable<D> for ::std::num::NonZeroU32 {
402 fn decode(d: &mut D) -> Result<Self, D::Error> {
403 d.read_u32().map(|d| ::std::num::NonZeroU32::new(d).unwrap())
407 impl<S: Encoder> Encodable<S> for str {
408 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
413 impl<S: Encoder> Encodable<S> for &str {
414 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
419 impl<S: Encoder> Encodable<S> for String {
420 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
421 s.emit_str(&self[..])
425 impl<D: Decoder> Decodable<D> for String {
426 fn decode(d: &mut D) -> Result<String, D::Error> {
427 Ok(d.read_str()?.into_owned())
431 impl<S: Encoder> Encodable<S> for () {
432 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
437 impl<D: Decoder> Decodable<D> for () {
438 fn decode(d: &mut D) -> Result<(), D::Error> {
443 impl<S: Encoder, T> Encodable<S> for PhantomData<T> {
444 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
449 impl<D: Decoder, T> Decodable<D> for PhantomData<T> {
450 fn decode(d: &mut D) -> Result<PhantomData<T>, D::Error> {
456 impl<D: Decoder, T: Decodable<D>> Decodable<D> for Box<[T]> {
457 fn decode(d: &mut D) -> Result<Box<[T]>, D::Error> {
458 let v: Vec<T> = Decodable::decode(d)?;
459 Ok(v.into_boxed_slice())
463 impl<S: Encoder, T: Encodable<S>> Encodable<S> for Rc<T> {
464 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
469 impl<D: Decoder, T: Decodable<D>> Decodable<D> for Rc<T> {
470 fn decode(d: &mut D) -> Result<Rc<T>, D::Error> {
471 Ok(Rc::new(Decodable::decode(d)?))
475 impl<S: Encoder, T: Encodable<S>> Encodable<S> for [T] {
476 default fn encode(&self, s: &mut S) -> Result<(), S::Error> {
477 s.emit_seq(self.len(), |s| {
478 for (i, e) in self.iter().enumerate() {
479 s.emit_seq_elt(i, |s| e.encode(s))?
486 impl<S: Encoder, T: Encodable<S>> Encodable<S> for Vec<T> {
487 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
488 let slice: &[T] = self;
493 impl<D: Decoder, T: Decodable<D>> Decodable<D> for Vec<T> {
494 default fn decode(d: &mut D) -> Result<Vec<T>, D::Error> {
495 d.read_seq(|d, len| {
496 let mut v = Vec::with_capacity(len);
498 v.push(d.read_seq_elt(|d| Decodable::decode(d))?);
505 impl<S: Encoder, T: Encodable<S>, const N: usize> Encodable<S> for [T; N] {
506 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
507 let slice: &[T] = self;
512 impl<D: Decoder, const N: usize> Decodable<D> for [u8; N] {
513 fn decode(d: &mut D) -> Result<[u8; N], D::Error> {
514 d.read_seq(|d, len| {
516 let mut v = [0u8; N];
518 v[i] = d.read_seq_elt(|d| Decodable::decode(d))?;
525 impl<'a, S: Encoder, T: Encodable<S>> Encodable<S> for Cow<'a, [T]>
527 [T]: ToOwned<Owned = Vec<T>>,
529 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
530 let slice: &[T] = self;
535 impl<D: Decoder, T: Decodable<D> + ToOwned> Decodable<D> for Cow<'static, [T]>
537 [T]: ToOwned<Owned = Vec<T>>,
539 fn decode(d: &mut D) -> Result<Cow<'static, [T]>, D::Error> {
540 let v: Vec<T> = Decodable::decode(d)?;
545 impl<S: Encoder, T: Encodable<S>> Encodable<S> for Option<T> {
546 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
547 s.emit_option(|s| match *self {
548 None => s.emit_option_none(),
549 Some(ref v) => s.emit_option_some(|s| v.encode(s)),
554 impl<D: Decoder, T: Decodable<D>> Decodable<D> for Option<T> {
555 fn decode(d: &mut D) -> Result<Option<T>, D::Error> {
556 d.read_option(|d, b| if b { Ok(Some(Decodable::decode(d)?)) } else { Ok(None) })
560 impl<S: Encoder, T1: Encodable<S>, T2: Encodable<S>> Encodable<S> for Result<T1, T2> {
561 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
562 s.emit_enum(|s| match *self {
564 s.emit_enum_variant("Ok", 0, 1, |s| s.emit_enum_variant_arg(true, |s| v.encode(s)))
567 s.emit_enum_variant("Err", 1, 1, |s| s.emit_enum_variant_arg(true, |s| v.encode(s)))
573 impl<D: Decoder, T1: Decodable<D>, T2: Decodable<D>> Decodable<D> for Result<T1, T2> {
574 fn decode(d: &mut D) -> Result<Result<T1, T2>, D::Error> {
576 d.read_enum_variant(&["Ok", "Err"], |d, disr| match disr {
577 0 => Ok(Ok(d.read_enum_variant_arg(|d| T1::decode(d))?)),
578 1 => Ok(Err(d.read_enum_variant_arg(|d| T2::decode(d))?)),
581 "Encountered invalid discriminant while \
591 ($name:ident, $($other:ident,)*) => (tuple! { $($other,)* })
594 /// Evaluates to the number of tokens passed to it.
596 /// Logarithmic counting: every one or two recursive expansions, the number of
597 /// tokens to count is divided by two, instead of being reduced by one.
598 /// Therefore, the recursion depth is the binary logarithm of the number of
599 /// tokens to count, and the expanded tree is likewise very small.
602 ($one:tt) => (1usize);
603 ($($pairs:tt $_p:tt)*) => (count!($($pairs)*) << 1usize);
604 ($odd:tt $($rest:tt)*) => (count!($($rest)*) | 1usize);
609 ( $($name:ident,)+ ) => (
610 impl<D: Decoder, $($name: Decodable<D>),+> Decodable<D> for ($($name,)+) {
611 #[allow(non_snake_case)]
612 fn decode(d: &mut D) -> Result<($($name,)+), D::Error> {
613 let len: usize = count!($($name)+);
614 d.read_tuple(len, |d| {
615 let ret = ($(d.read_tuple_arg(|d| -> Result<$name, D::Error> {
622 impl<S: Encoder, $($name: Encodable<S>),+> Encodable<S> for ($($name,)+) {
623 #[allow(non_snake_case)]
624 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
625 let ($(ref $name,)+) = *self;
627 $(let $name = $name; n += 1;)+
628 s.emit_tuple(n, |s| {
630 $(s.emit_tuple_arg({ i+=1; i-1 }, |s| $name.encode(s))?;)+
639 tuple! { T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, }
641 impl<S: Encoder> Encodable<S> for path::Path {
642 fn encode(&self, e: &mut S) -> Result<(), S::Error> {
643 self.to_str().unwrap().encode(e)
647 impl<S: Encoder> Encodable<S> for path::PathBuf {
648 fn encode(&self, e: &mut S) -> Result<(), S::Error> {
649 path::Path::encode(self, e)
653 impl<D: Decoder> Decodable<D> for path::PathBuf {
654 fn decode(d: &mut D) -> Result<path::PathBuf, D::Error> {
655 let bytes: String = Decodable::decode(d)?;
656 Ok(path::PathBuf::from(bytes))
660 impl<S: Encoder, T: Encodable<S> + Copy> Encodable<S> for Cell<T> {
661 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
666 impl<D: Decoder, T: Decodable<D> + Copy> Decodable<D> for Cell<T> {
667 fn decode(d: &mut D) -> Result<Cell<T>, D::Error> {
668 Ok(Cell::new(Decodable::decode(d)?))
673 // Should use `try_borrow`, returning an
674 // `encoder.error("attempting to Encode borrowed RefCell")`
675 // from `encode` when `try_borrow` returns `None`.
677 impl<S: Encoder, T: Encodable<S>> Encodable<S> for RefCell<T> {
678 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
679 self.borrow().encode(s)
683 impl<D: Decoder, T: Decodable<D>> Decodable<D> for RefCell<T> {
684 fn decode(d: &mut D) -> Result<RefCell<T>, D::Error> {
685 Ok(RefCell::new(Decodable::decode(d)?))
689 impl<S: Encoder, T: Encodable<S>> Encodable<S> for Arc<T> {
690 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
695 impl<D: Decoder, T: Decodable<D>> Decodable<D> for Arc<T> {
696 fn decode(d: &mut D) -> Result<Arc<T>, D::Error> {
697 Ok(Arc::new(Decodable::decode(d)?))
701 impl<S: Encoder, T: ?Sized + Encodable<S>> Encodable<S> for Box<T> {
702 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
706 impl<D: Decoder, T: Decodable<D>> Decodable<D> for Box<T> {
707 fn decode(d: &mut D) -> Result<Box<T>, D::Error> {
708 Ok(Box::new(Decodable::decode(d)?))