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, _name: &str, 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)?;
62 fn emit_enum_variant_arg<F>(&mut self, _a_idx: usize, f: F) -> Result<(), Self::Error>
64 F: FnOnce(&mut Self) -> Result<(), Self::Error>,
69 fn emit_enum_struct_variant<F>(
75 ) -> Result<(), Self::Error>
77 F: FnOnce(&mut Self) -> Result<(), Self::Error>,
79 self.emit_enum_variant(v_name, v_id, len, f)
82 fn emit_enum_struct_variant_field<F>(
87 ) -> Result<(), Self::Error>
89 F: FnOnce(&mut Self) -> Result<(), Self::Error>,
91 self.emit_enum_variant_arg(f_idx, f)
95 fn emit_struct<F>(&mut self, _name: &str, _len: usize, f: F) -> Result<(), Self::Error>
97 F: FnOnce(&mut Self) -> Result<(), Self::Error>,
103 fn emit_struct_field<F>(
108 ) -> Result<(), Self::Error>
110 F: FnOnce(&mut Self) -> Result<(), Self::Error>,
116 fn emit_tuple<F>(&mut self, _len: usize, f: F) -> Result<(), Self::Error>
118 F: FnOnce(&mut Self) -> Result<(), Self::Error>,
124 fn emit_tuple_arg<F>(&mut self, _idx: usize, f: F) -> Result<(), Self::Error>
126 F: FnOnce(&mut Self) -> Result<(), Self::Error>,
131 fn emit_tuple_struct<F>(&mut self, _name: &str, len: usize, f: F) -> Result<(), Self::Error>
133 F: FnOnce(&mut Self) -> Result<(), Self::Error>,
135 self.emit_tuple(len, f)
138 fn emit_tuple_struct_arg<F>(&mut self, f_idx: usize, f: F) -> Result<(), Self::Error>
140 F: FnOnce(&mut Self) -> Result<(), Self::Error>,
142 self.emit_tuple_arg(f_idx, f)
145 // Specialized types:
146 fn emit_option<F>(&mut self, f: F) -> Result<(), Self::Error>
148 F: FnOnce(&mut Self) -> Result<(), Self::Error>,
150 self.emit_enum("Option", f)
154 fn emit_option_none(&mut self) -> Result<(), Self::Error> {
155 self.emit_enum_variant("None", 0, 0, |_| Ok(()))
158 fn emit_option_some<F>(&mut self, f: F) -> Result<(), Self::Error>
160 F: FnOnce(&mut Self) -> Result<(), Self::Error>,
162 self.emit_enum_variant("Some", 1, 1, f)
165 fn emit_seq<F>(&mut self, len: usize, f: F) -> Result<(), Self::Error>
167 F: FnOnce(&mut Self) -> Result<(), Self::Error>,
169 self.emit_usize(len)?;
174 fn emit_seq_elt<F>(&mut self, _idx: usize, f: F) -> Result<(), Self::Error>
176 F: FnOnce(&mut Self) -> Result<(), Self::Error>,
181 fn emit_map<F>(&mut self, len: usize, f: F) -> Result<(), Self::Error>
183 F: FnOnce(&mut Self) -> Result<(), Self::Error>,
185 self.emit_usize(len)?;
190 fn emit_map_elt_key<F>(&mut self, _idx: usize, f: F) -> Result<(), Self::Error>
192 F: FnOnce(&mut Self) -> Result<(), Self::Error>,
198 fn emit_map_elt_val<F>(&mut self, _idx: usize, f: F) -> Result<(), Self::Error>
200 F: FnOnce(&mut Self) -> Result<(), Self::Error>,
210 fn read_nil(&mut self) -> Result<(), Self::Error>;
211 fn read_usize(&mut self) -> Result<usize, Self::Error>;
212 fn read_u128(&mut self) -> Result<u128, Self::Error>;
213 fn read_u64(&mut self) -> Result<u64, Self::Error>;
214 fn read_u32(&mut self) -> Result<u32, Self::Error>;
215 fn read_u16(&mut self) -> Result<u16, Self::Error>;
216 fn read_u8(&mut self) -> Result<u8, Self::Error>;
217 fn read_isize(&mut self) -> Result<isize, Self::Error>;
218 fn read_i128(&mut self) -> Result<i128, Self::Error>;
219 fn read_i64(&mut self) -> Result<i64, Self::Error>;
220 fn read_i32(&mut self) -> Result<i32, Self::Error>;
221 fn read_i16(&mut self) -> Result<i16, Self::Error>;
222 fn read_i8(&mut self) -> Result<i8, Self::Error>;
223 fn read_bool(&mut self) -> Result<bool, Self::Error>;
224 fn read_f64(&mut self) -> Result<f64, Self::Error>;
225 fn read_f32(&mut self) -> Result<f32, Self::Error>;
226 fn read_char(&mut self) -> Result<char, Self::Error>;
227 fn read_str(&mut self) -> Result<Cow<'_, str>, Self::Error>;
228 fn read_raw_bytes_into(&mut self, s: &mut [u8]) -> Result<(), Self::Error>;
232 fn read_enum<T, F>(&mut self, _name: &str, f: F) -> Result<T, Self::Error>
234 F: FnOnce(&mut Self) -> Result<T, Self::Error>,
240 fn read_enum_variant<T, F>(&mut self, _names: &[&str], mut f: F) -> Result<T, Self::Error>
242 F: FnMut(&mut Self, usize) -> Result<T, Self::Error>,
244 let disr = self.read_usize()?;
249 fn read_enum_variant_arg<T, F>(&mut self, _a_idx: usize, f: F) -> Result<T, Self::Error>
251 F: FnOnce(&mut Self) -> Result<T, Self::Error>,
256 fn read_enum_struct_variant<T, F>(&mut self, names: &[&str], f: F) -> Result<T, Self::Error>
258 F: FnMut(&mut Self, usize) -> Result<T, Self::Error>,
260 self.read_enum_variant(names, f)
263 fn read_enum_struct_variant_field<T, F>(
268 ) -> Result<T, Self::Error>
270 F: FnOnce(&mut Self) -> Result<T, Self::Error>,
272 self.read_enum_variant_arg(f_idx, f)
276 fn read_struct<T, F>(&mut self, _s_name: &str, _len: usize, f: F) -> Result<T, Self::Error>
278 F: FnOnce(&mut Self) -> Result<T, Self::Error>,
284 fn read_struct_field<T, F>(
289 ) -> Result<T, Self::Error>
291 F: FnOnce(&mut Self) -> Result<T, Self::Error>,
297 fn read_tuple<T, F>(&mut self, _len: usize, f: F) -> Result<T, Self::Error>
299 F: FnOnce(&mut Self) -> Result<T, Self::Error>,
305 fn read_tuple_arg<T, F>(&mut self, _a_idx: usize, f: F) -> Result<T, Self::Error>
307 F: FnOnce(&mut Self) -> Result<T, Self::Error>,
312 fn read_tuple_struct<T, F>(&mut self, _s_name: &str, len: usize, f: F) -> Result<T, Self::Error>
314 F: FnOnce(&mut Self) -> Result<T, Self::Error>,
316 self.read_tuple(len, f)
319 fn read_tuple_struct_arg<T, F>(&mut self, a_idx: usize, f: F) -> Result<T, Self::Error>
321 F: FnOnce(&mut Self) -> Result<T, Self::Error>,
323 self.read_tuple_arg(a_idx, f)
326 // Specialized types:
327 fn read_option<T, F>(&mut self, mut f: F) -> Result<T, Self::Error>
329 F: FnMut(&mut Self, bool) -> Result<T, Self::Error>,
331 self.read_enum("Option", move |this| {
332 this.read_enum_variant(&["None", "Some"], move |this, idx| match idx {
335 _ => Err(this.error("read_option: expected 0 for None or 1 for Some")),
340 fn read_seq<T, F>(&mut self, f: F) -> Result<T, Self::Error>
342 F: FnOnce(&mut Self, usize) -> Result<T, Self::Error>,
344 let len = self.read_usize()?;
349 fn read_seq_elt<T, F>(&mut self, _idx: usize, f: F) -> Result<T, Self::Error>
351 F: FnOnce(&mut Self) -> Result<T, Self::Error>,
356 fn read_map<T, F>(&mut self, f: F) -> Result<T, Self::Error>
358 F: FnOnce(&mut Self, usize) -> Result<T, Self::Error>,
360 let len = self.read_usize()?;
365 fn read_map_elt_key<T, F>(&mut self, _idx: usize, f: F) -> Result<T, Self::Error>
367 F: FnOnce(&mut Self) -> Result<T, Self::Error>,
373 fn read_map_elt_val<T, F>(&mut self, _idx: usize, f: F) -> Result<T, Self::Error>
375 F: FnOnce(&mut Self) -> Result<T, Self::Error>,
381 fn error(&mut self, err: &str) -> Self::Error;
384 /// Trait for types that can be serialized
386 /// This can be implemented using the `Encodable`, `TyEncodable` and
387 /// `MetadataEncodable` macros.
389 /// * `Encodable` should be used in crates that don't depend on
391 /// * `MetadataEncodable` is used in `rustc_metadata` for types that contain
392 /// `rustc_metadata::rmeta::Lazy`.
393 /// * `TyEncodable` should be used for types that are only serialized in crate
394 /// metadata or the incremental cache. This is most types in `rustc_middle`.
395 pub trait Encodable<S: Encoder> {
396 fn encode(&self, s: &mut S) -> Result<(), S::Error>;
399 /// Trait for types that can be deserialized
401 /// This can be implemented using the `Decodable`, `TyDecodable` and
402 /// `MetadataDecodable` macros.
404 /// * `Decodable` should be used in crates that don't depend on
406 /// * `MetadataDecodable` is used in `rustc_metadata` for types that contain
407 /// `rustc_metadata::rmeta::Lazy`.
408 /// * `TyDecodable` should be used for types that are only serialized in crate
409 /// metadata or the incremental cache. This is most types in `rustc_middle`.
410 pub trait Decodable<D: Decoder>: Sized {
411 fn decode(d: &mut D) -> Result<Self, D::Error>;
414 macro_rules! direct_serialize_impls {
415 ($($ty:ident $emit_method:ident $read_method:ident),*) => {
417 impl<S: Encoder> Encodable<S> for $ty {
418 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
419 s.$emit_method(*self)
423 impl<D: Decoder> Decodable<D> for $ty {
424 fn decode(d: &mut D) -> Result<$ty, D::Error> {
432 direct_serialize_impls! {
433 usize emit_usize read_usize,
435 u16 emit_u16 read_u16,
436 u32 emit_u32 read_u32,
437 u64 emit_u64 read_u64,
438 u128 emit_u128 read_u128,
439 isize emit_isize read_isize,
441 i16 emit_i16 read_i16,
442 i32 emit_i32 read_i32,
443 i64 emit_i64 read_i64,
444 i128 emit_i128 read_i128,
445 f32 emit_f32 read_f32,
446 f64 emit_f64 read_f64,
447 bool emit_bool read_bool,
448 char emit_char read_char
451 impl<S: Encoder> Encodable<S> for ::std::num::NonZeroU32 {
452 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
453 s.emit_u32(self.get())
457 impl<D: Decoder> Decodable<D> for ::std::num::NonZeroU32 {
458 fn decode(d: &mut D) -> Result<Self, D::Error> {
459 d.read_u32().map(|d| ::std::num::NonZeroU32::new(d).unwrap())
463 impl<S: Encoder> Encodable<S> for str {
464 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
469 impl<S: Encoder> Encodable<S> for &str {
470 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
475 impl<S: Encoder> Encodable<S> for String {
476 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
477 s.emit_str(&self[..])
481 impl<D: Decoder> Decodable<D> for String {
482 fn decode(d: &mut D) -> Result<String, D::Error> {
483 Ok(d.read_str()?.into_owned())
487 impl<S: Encoder> Encodable<S> for () {
488 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
493 impl<D: Decoder> Decodable<D> for () {
494 fn decode(d: &mut D) -> Result<(), D::Error> {
499 impl<S: Encoder, T> Encodable<S> for PhantomData<T> {
500 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
505 impl<D: Decoder, T> Decodable<D> for PhantomData<T> {
506 fn decode(d: &mut D) -> Result<PhantomData<T>, D::Error> {
512 impl<D: Decoder, T: Decodable<D>> Decodable<D> for Box<[T]> {
513 fn decode(d: &mut D) -> Result<Box<[T]>, D::Error> {
514 let v: Vec<T> = Decodable::decode(d)?;
515 Ok(v.into_boxed_slice())
519 impl<S: Encoder, T: Encodable<S>> Encodable<S> for Rc<T> {
520 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
525 impl<D: Decoder, T: Decodable<D>> Decodable<D> for Rc<T> {
526 fn decode(d: &mut D) -> Result<Rc<T>, D::Error> {
527 Ok(Rc::new(Decodable::decode(d)?))
531 impl<S: Encoder, T: Encodable<S>> Encodable<S> for [T] {
532 default fn encode(&self, s: &mut S) -> Result<(), S::Error> {
533 s.emit_seq(self.len(), |s| {
534 for (i, e) in self.iter().enumerate() {
535 s.emit_seq_elt(i, |s| e.encode(s))?
542 impl<S: Encoder, T: Encodable<S>> Encodable<S> for Vec<T> {
543 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
544 let slice: &[T] = self;
549 impl<D: Decoder, T: Decodable<D>> Decodable<D> for Vec<T> {
550 default fn decode(d: &mut D) -> Result<Vec<T>, D::Error> {
551 d.read_seq(|d, len| {
552 let mut v = Vec::with_capacity(len);
554 v.push(d.read_seq_elt(i, |d| Decodable::decode(d))?);
561 impl<S: Encoder, T: Encodable<S>, const N: usize> Encodable<S> for [T; N] {
562 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
563 let slice: &[T] = self;
568 impl<D: Decoder, const N: usize> Decodable<D> for [u8; N] {
569 fn decode(d: &mut D) -> Result<[u8; N], D::Error> {
570 d.read_seq(|d, len| {
572 let mut v = [0u8; N];
574 v[i] = d.read_seq_elt(i, |d| Decodable::decode(d))?;
581 impl<'a, S: Encoder, T: Encodable<S>> Encodable<S> for Cow<'a, [T]>
583 [T]: ToOwned<Owned = Vec<T>>,
585 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
586 let slice: &[T] = self;
591 impl<D: Decoder, T: Decodable<D> + ToOwned> Decodable<D> for Cow<'static, [T]>
593 [T]: ToOwned<Owned = Vec<T>>,
595 fn decode(d: &mut D) -> Result<Cow<'static, [T]>, D::Error> {
596 let v: Vec<T> = Decodable::decode(d)?;
601 impl<S: Encoder, T: Encodable<S>> Encodable<S> for Option<T> {
602 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
603 s.emit_option(|s| match *self {
604 None => s.emit_option_none(),
605 Some(ref v) => s.emit_option_some(|s| v.encode(s)),
610 impl<D: Decoder, T: Decodable<D>> Decodable<D> for Option<T> {
611 fn decode(d: &mut D) -> Result<Option<T>, D::Error> {
612 d.read_option(|d, b| if b { Ok(Some(Decodable::decode(d)?)) } else { Ok(None) })
616 impl<S: Encoder, T1: Encodable<S>, T2: Encodable<S>> Encodable<S> for Result<T1, T2> {
617 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
618 s.emit_enum("Result", |s| match *self {
620 s.emit_enum_variant("Ok", 0, 1, |s| s.emit_enum_variant_arg(0, |s| v.encode(s)))
623 s.emit_enum_variant("Err", 1, 1, |s| s.emit_enum_variant_arg(0, |s| v.encode(s)))
629 impl<D: Decoder, T1: Decodable<D>, T2: Decodable<D>> Decodable<D> for Result<T1, T2> {
630 fn decode(d: &mut D) -> Result<Result<T1, T2>, D::Error> {
631 d.read_enum("Result", |d| {
632 d.read_enum_variant(&["Ok", "Err"], |d, disr| match disr {
633 0 => Ok(Ok(d.read_enum_variant_arg(0, |d| T1::decode(d))?)),
634 1 => Ok(Err(d.read_enum_variant_arg(0, |d| T2::decode(d))?)),
637 "Encountered invalid discriminant while \
647 ($name:ident, $($other:ident,)*) => (tuple! { $($other,)* })
650 /// Evaluates to the number of tokens passed to it.
652 /// Logarithmic counting: every one or two recursive expansions, the number of
653 /// tokens to count is divided by two, instead of being reduced by one.
654 /// Therefore, the recursion depth is the binary logarithm of the number of
655 /// tokens to count, and the expanded tree is likewise very small.
658 ($one:tt) => (1usize);
659 ($($pairs:tt $_p:tt)*) => (count!($($pairs)*) << 1usize);
660 ($odd:tt $($rest:tt)*) => (count!($($rest)*) | 1usize);
665 ( $($name:ident,)+ ) => (
666 impl<D: Decoder, $($name: Decodable<D>),+> Decodable<D> for ($($name,)+) {
667 #[allow(non_snake_case)]
668 fn decode(d: &mut D) -> Result<($($name,)+), D::Error> {
669 let len: usize = count!($($name)+);
670 d.read_tuple(len, |d| {
672 let ret = ($(d.read_tuple_arg({ i+=1; i-1 }, |d| -> Result<$name, D::Error> {
679 impl<S: Encoder, $($name: Encodable<S>),+> Encodable<S> for ($($name,)+) {
680 #[allow(non_snake_case)]
681 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
682 let ($(ref $name,)+) = *self;
684 $(let $name = $name; n += 1;)+
685 s.emit_tuple(n, |s| {
687 $(s.emit_tuple_arg({ i+=1; i-1 }, |s| $name.encode(s))?;)+
696 tuple! { T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, }
698 impl<S: Encoder> Encodable<S> for path::Path {
699 fn encode(&self, e: &mut S) -> Result<(), S::Error> {
700 self.to_str().unwrap().encode(e)
704 impl<S: Encoder> Encodable<S> for path::PathBuf {
705 fn encode(&self, e: &mut S) -> Result<(), S::Error> {
706 path::Path::encode(self, e)
710 impl<D: Decoder> Decodable<D> for path::PathBuf {
711 fn decode(d: &mut D) -> Result<path::PathBuf, D::Error> {
712 let bytes: String = Decodable::decode(d)?;
713 Ok(path::PathBuf::from(bytes))
717 impl<S: Encoder, T: Encodable<S> + Copy> Encodable<S> for Cell<T> {
718 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
723 impl<D: Decoder, T: Decodable<D> + Copy> Decodable<D> for Cell<T> {
724 fn decode(d: &mut D) -> Result<Cell<T>, D::Error> {
725 Ok(Cell::new(Decodable::decode(d)?))
730 // Should use `try_borrow`, returning a
731 // `encoder.error("attempting to Encode borrowed RefCell")`
732 // from `encode` when `try_borrow` returns `None`.
734 impl<S: Encoder, T: Encodable<S>> Encodable<S> for RefCell<T> {
735 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
736 self.borrow().encode(s)
740 impl<D: Decoder, T: Decodable<D>> Decodable<D> for RefCell<T> {
741 fn decode(d: &mut D) -> Result<RefCell<T>, D::Error> {
742 Ok(RefCell::new(Decodable::decode(d)?))
746 impl<S: Encoder, T: Encodable<S>> Encodable<S> for Arc<T> {
747 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
752 impl<D: Decoder, T: Decodable<D>> Decodable<D> for Arc<T> {
753 fn decode(d: &mut D) -> Result<Arc<T>, D::Error> {
754 Ok(Arc::new(Decodable::decode(d)?))
758 impl<S: Encoder, T: ?Sized + Encodable<S>> Encodable<S> for Box<T> {
759 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
763 impl<D: Decoder, T: Decodable<D>> Decodable<D> for Box<T> {
764 fn decode(d: &mut D) -> Result<Box<T>, D::Error> {
765 Ok(box Decodable::decode(d)?)