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// Some parts copyright Serde developers under the MIT / Apache-2.0 licenses at your option.
// See `serde` version `v1.0.169` for the parts where MIT / Apache-2.0 applies.
mod impls;
#[cfg(feature = "serde")]
pub mod serde;
#[doc(hidden)]
pub use impls::{visit_named_product, visit_seq_product};
use smallvec::SmallVec;
use std::borrow::Borrow;
use std::collections::BTreeMap;
use std::fmt;
use std::marker::PhantomData;
/// A **data format** that can deserialize any data structure supported by SATS.
///
/// The `Deserializer` trait in SATS performs the same function as [`serde::Deserializer`] in [`serde`].
/// See the documentation of [`serde::Deserializer`] for more information of the data model.
///
/// Implementations of `Deserialize` map themselves into this data model
/// by passing to the `Deserializer` a visitor that can receive the necessary types.
/// The kind of visitor depends on the `deserialize_*` method.
/// Unlike in Serde, there isn't a single monolithic `Visitor` trait,
/// but rather, this functionality is split up into more targeted traits such as `SumVisitor<'de>`.
///
/// The lifetime `'de` allows us to deserialize lifetime-generic types in a zero-copy fashion.
///
/// [`serde::Deserializer`]: ::serde::Deserializer
/// [`serde`]: https://crates.io/crates/serde
pub trait Deserializer<'de>: Sized {
/// The error type that can be returned if some error occurs during deserialization.
type Error: Error;
/// Deserializes a product value from the input.
fn deserialize_product<V: ProductVisitor<'de>>(self, visitor: V) -> Result<V::Output, Self::Error>;
/// Deserializes a sum value from the input.
///
/// The entire process of deserializing a sum, starting from `deserialize(args...)`, is roughly:
///
/// - [`deserialize`][Deserialize::deserialize] calls this method,
/// [`deserialize_sum(sum_visitor)`](Deserializer::deserialize_sum),
/// providing us with a [`sum_visitor`](SumVisitor).
///
/// - This method calls [`sum_visitor.visit_sum(sum_access)`](SumVisitor::visit_sum),
/// where [`sum_access`](SumAccess) deals with extracting the tag and the variant data,
/// with the latter provided as [`VariantAccess`]).
/// The `SumVisitor` will then assemble these into the representation of a sum value
/// that the [`Deserialize`] implementation wants.
///
/// - [`visit_sum`](SumVisitor::visit_sum) then calls
/// [`sum_access.variant(variant_visitor)`](SumAccess::variant),
/// and uses the provided `variant_visitor` to translate extracted variant names / tags
/// into something that is meaningful for `visit_sum`, e.g., an index.
///
/// The call to `variant` will also return [`variant_access`](VariantAccess)
/// that can deserialize the contents of the variant.
///
/// - Finally, after `variant` returns,
/// `visit_sum` deserializes the variant data using
/// [`variant_access.deserialize_seed(seed)`](VariantAccess::deserialize_seed)
/// or [`variant_access.deserialize()`](VariantAccess::deserialize).
/// This part may require some conditional logic depending on the identified variant.
///
///
/// The data format will also return an object ([`VariantAccess`])
/// that can deserialize the contents of the variant.
fn deserialize_sum<V: SumVisitor<'de>>(self, visitor: V) -> Result<V::Output, Self::Error>;
/// Deserializes a `bool` value from the input.
fn deserialize_bool(self) -> Result<bool, Self::Error>;
/// Deserializes a `u8` value from the input.
fn deserialize_u8(self) -> Result<u8, Self::Error>;
/// Deserializes a `u16` value from the input.
fn deserialize_u16(self) -> Result<u16, Self::Error>;
/// Deserializes a `u32` value from the input.
fn deserialize_u32(self) -> Result<u32, Self::Error>;
/// Deserializes a `u64` value from the input.
fn deserialize_u64(self) -> Result<u64, Self::Error>;
/// Deserializes a `u128` value from the input.
fn deserialize_u128(self) -> Result<u128, Self::Error>;
/// Deserializes an `i8 value from the input.
fn deserialize_i8(self) -> Result<i8, Self::Error>;
/// Deserializes an `i16 value from the input.
fn deserialize_i16(self) -> Result<i16, Self::Error>;
/// Deserializes an `i32 value from the input.
fn deserialize_i32(self) -> Result<i32, Self::Error>;
/// Deserializes an `i64 value from the input.
fn deserialize_i64(self) -> Result<i64, Self::Error>;
/// Deserializes an `i128 value from the input.
fn deserialize_i128(self) -> Result<i128, Self::Error>;
/// Deserializes an `f32 value from the input.
fn deserialize_f32(self) -> Result<f32, Self::Error>;
/// Deserializes an `f64 value from the input.
fn deserialize_f64(self) -> Result<f64, Self::Error>;
/// Deserializes a string-like object the input.
fn deserialize_str<V: SliceVisitor<'de, str>>(self, visitor: V) -> Result<V::Output, Self::Error>;
/// Deserializes an `&str` string value.
fn deserialize_str_slice(self) -> Result<&'de str, Self::Error> {
self.deserialize_str(BorrowedSliceVisitor)
}
/// Deserializes a byte slice-like value.
fn deserialize_bytes<V: SliceVisitor<'de, [u8]>>(self, visitor: V) -> Result<V::Output, Self::Error>;
/// Deserializes an array value.
///
/// This is typically the same as [`deserialize_array_seed`](Deserializer::deserialize_array_seed)
/// with an uninteresting `seed` value.
fn deserialize_array<V: ArrayVisitor<'de, T>, T: Deserialize<'de>>(
self,
visitor: V,
) -> Result<V::Output, Self::Error> {
self.deserialize_array_seed(visitor, PhantomData)
}
/// Deserializes an array value.
///
/// The deserialization is provided with a `seed` value.
fn deserialize_array_seed<V: ArrayVisitor<'de, T::Output>, T: DeserializeSeed<'de> + Clone>(
self,
visitor: V,
seed: T,
) -> Result<V::Output, Self::Error>;
/// Deserializes a map value.
///
/// This is typically the same as [`deserialize_map_seed`](Deserializer::deserialize_map_seed)
/// with an uninteresting `seed` value.
fn deserialize_map<Vi: MapVisitor<'de, K, V>, K: Deserialize<'de>, V: Deserialize<'de>>(
self,
visitor: Vi,
) -> Result<Vi::Output, Self::Error> {
self.deserialize_map_seed(visitor, PhantomData, PhantomData)
}
/// Deserializes a map value.
///
/// The deserialization is provided with `kseed` and `vseed` for keys and values respectively.
fn deserialize_map_seed<
Vi: MapVisitor<'de, K::Output, V::Output>,
K: DeserializeSeed<'de> + Clone,
V: DeserializeSeed<'de> + Clone,
>(
self,
visitor: Vi,
kseed: K,
vseed: V,
) -> Result<Vi::Output, Self::Error>;
}
/// The `Error` trait allows [`Deserialize`] implementations to create descriptive error messages
/// belonging to the [`Deserializer`] against which they are currently running.
///
/// Every [`Deserializer`] declares an [`Error`] type
/// that encompasses both general-purpose deserialization errors
/// as well as errors specific to the particular deserialization format.
///
/// Most deserializers should only need to provide the [`Error::custom`] method
/// and inherit the default behavior for the other methods.
pub trait Error: Sized {
/// Raised when there is general error when deserializing a type.
fn custom(msg: impl fmt::Display) -> Self;
/// The product length was not as promised.
fn invalid_product_length<'de, T: ProductVisitor<'de>>(len: usize, expected: &T) -> Self {
Self::custom(format_args!(
"invalid length {}, expected {}",
len,
fmt_invalid_len(expected)
))
}
/// There was a missing field at `index`.
fn missing_field<'de, T: ProductVisitor<'de>>(index: usize, field_name: Option<&str>, prod: &T) -> Self {
Self::custom(error_on_field("missing ", index, field_name, prod))
}
/// A field with `index` was specified more than once.
fn duplicate_field<'de, T: ProductVisitor<'de>>(index: usize, field_name: Option<&str>, prod: &T) -> Self {
Self::custom(error_on_field("duplicate ", index, field_name, prod))
}
/// A field with name `field_name` does not exist.
fn unknown_field_name<'de, T: FieldNameVisitor<'de>>(field_name: &str, expected: &T) -> Self {
let el_ty = match expected.kind() {
ProductKind::Normal => "field",
ProductKind::ReducerArgs => "reducer argument",
};
if let Some(one_of) = one_of_names(|n| expected.field_names(n)) {
Self::custom(format_args!("unknown {el_ty} `{field_name}`, expected {one_of}"))
} else {
Self::custom(format_args!("unknown {el_ty} `{field_name}`, there are no {el_ty}s"))
}
}
/// The `tag` does not specify a variant of the sum type.
fn unknown_variant_tag<'de, T: SumVisitor<'de>>(tag: u8, expected: &T) -> Self {
Self::custom(format_args!(
"unknown tag {tag:#x} for sum type {}",
expected.sum_name().unwrap_or("<sum>"),
))
}
/// The `name` is not that of a variant of the sum type.
fn unknown_variant_name<T: VariantVisitor>(name: &str, expected: &T) -> Self {
if let Some(one_of) = one_of_names(|n| expected.variant_names(n)) {
Self::custom(format_args!("unknown variant `{name}`, expected {one_of}",))
} else {
Self::custom(format_args!("unknown variant `{name}`, there are no variants"))
}
}
}
/// Turns a closure `impl Fn(&mut Formatter) -> Result` into a `Display`able object.
pub struct FDisplay<F>(F);
impl<F: Fn(&mut fmt::Formatter) -> fmt::Result> fmt::Display for FDisplay<F> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
(self.0)(f)
}
}
/// Turns a closure `F: Fn(&mut Formatter) -> Result` into a `Display`able object.
pub fn fmt_fn<F: Fn(&mut fmt::Formatter) -> fmt::Result>(f: F) -> FDisplay<F> {
FDisplay(f)
}
/// Returns an error message for a `problem` with field at `index` and an optional `name`.
fn error_on_field<'a, 'de>(
problem: &'static str,
index: usize,
name: Option<&'a str>,
prod: &impl ProductVisitor<'de>,
) -> impl fmt::Display + 'a {
let field_kind = match prod.product_kind() {
ProductKind::Normal => "field",
ProductKind::ReducerArgs => "reducer argument",
};
fmt_fn(move |f| {
// e.g. "missing field `foo`"
f.write_str(problem)?;
f.write_str(field_kind)?;
if let Some(name) = name {
write!(f, " `{}`", name)
} else {
write!(f, " (index {})", index)
}
})
}
/// Returns an error message for invalid product type lengths.
fn fmt_invalid_len<'de>(
expected: &impl ProductVisitor<'de>,
) -> FDisplay<impl '_ + Fn(&mut fmt::Formatter) -> fmt::Result> {
fmt_fn(|f| {
let ty = match expected.product_kind() {
ProductKind::Normal => "product type",
ProductKind::ReducerArgs => "reducer args for",
};
let name = expected.product_name().unwrap_or("<product>");
let len = expected.product_len();
write!(f, "{ty} {name} with {len} elements")
})
}
/// A visitor walking through a [`Deserializer`] for products.
pub trait ProductVisitor<'de> {
/// The resulting product.
type Output;
/// Returns the name of the product, if any.
fn product_name(&self) -> Option<&str>;
/// Returns the length of the product.
fn product_len(&self) -> usize;
/// Returns the kind of the product.
fn product_kind(&self) -> ProductKind {
ProductKind::Normal
}
/// The input contains an unnamed product.
fn visit_seq_product<A: SeqProductAccess<'de>>(self, prod: A) -> Result<Self::Output, A::Error>;
/// The input contains a named product.
fn visit_named_product<A: NamedProductAccess<'de>>(self, prod: A) -> Result<Self::Output, A::Error>;
}
/// What kind of product is this?
#[derive(Clone, Copy)]
pub enum ProductKind {
// A normal product.
Normal,
/// A product in the context of reducer arguments.
ReducerArgs,
}
/// Provides a [`ProductVisitor`] with access to each element of the unnamed product in the input.
///
/// This is a trait that a [`Deserializer`] passes to a [`ProductVisitor`] implementation.
pub trait SeqProductAccess<'de> {
/// The error type that can be returned if some error occurs during deserialization.
type Error: Error;
/// Deserializes an `T` from the input.
///
/// Returns `Ok(Some(value))` for the next element in the product,
/// or `Ok(None)` if there are no more remaining items.
///
/// This method exists as a convenience for [`Deserialize`] implementations.
/// [`SeqProductAccess`] implementations should not override the default behavior.
fn next_element<T: Deserialize<'de>>(&mut self) -> Result<Option<T>, Self::Error> {
self.next_element_seed(PhantomData)
}
/// Statefully deserializes `T::Output` from the input provided a `seed` value.
///
/// Returns `Ok(Some(value))` for the next element in the unnamed product,
/// or `Ok(None)` if there are no more remaining items.
///
/// [`Deserialize`] implementations should typically use
/// [`next_element`](SeqProductAccess::next_element) instead.
fn next_element_seed<T: DeserializeSeed<'de>>(&mut self, seed: T) -> Result<Option<T::Output>, Self::Error>;
}
/// Provides a [`ProductVisitor`] with access to each element of the named product in the input.
///
/// This is a trait that a [`Deserializer`] passes to a [`ProductVisitor`] implementation.
pub trait NamedProductAccess<'de> {
/// The error type that can be returned if some error occurs during deserialization.
type Error: Error;
/// Deserializes field name of type `V::Output` from the input using a visitor
/// provided by the deserializer.
fn get_field_ident<V: FieldNameVisitor<'de>>(&mut self, visitor: V) -> Result<Option<V::Output>, Self::Error>;
/// Deserializes field value of type `T` from the input.
///
/// This method exists as a convenience for [`Deserialize`] implementations.
/// [`NamedProductAccess`] implementations should not override the default behavior.
fn get_field_value<T: Deserialize<'de>>(&mut self) -> Result<T, Self::Error> {
self.get_field_value_seed(PhantomData)
}
/// Statefully deserializes the field value `T::Output` from the input provided a `seed` value.
///
/// [`Deserialize`] implementations should typically use
/// [`next_element`](NamedProductAccess::get_field_value) instead.
fn get_field_value_seed<T: DeserializeSeed<'de>>(&mut self, seed: T) -> Result<T::Output, Self::Error>;
}
/// Visitor used to deserialize the name of a field.
pub trait FieldNameVisitor<'de> {
/// The resulting field name.
type Output;
/// The sort of product deserialized.
fn kind(&self) -> ProductKind {
ProductKind::Normal
}
/// Provides the visitor the chance to add valid names into `names`.
fn field_names(&self, names: &mut dyn ValidNames);
fn visit<E: Error>(self, name: &str) -> Result<Self::Output, E>;
}
/// A trait for types storing a set of valid names.
pub trait ValidNames {
/// Adds the name `s` to the set.
fn push(&mut self, s: &str);
/// Runs the function `names` provided with `self` as the store
/// and then returns back `self`.
/// This method exists for convenience.
fn run(mut self, names: &impl Fn(&mut dyn ValidNames)) -> Self
where
Self: Sized,
{
names(&mut self);
self
}
}
impl dyn ValidNames + '_ {
/// Adds the names in `iter` to the set.
pub fn extend<I: IntoIterator>(&mut self, iter: I)
where
I::Item: AsRef<str>,
{
for name in iter {
self.push(name.as_ref())
}
}
}
/// A visitor walking through a [`Deserializer`] for sums.
///
/// This side is provided by a [`Deserialize`] implementation
/// when calling [`Deserializer::deserialize_sum`].
pub trait SumVisitor<'de> {
/// The resulting sum.
type Output;
/// Returns the name of the sum, if any.
fn sum_name(&self) -> Option<&str>;
/// Returns whether an option is expected.
///
/// The provided implementation does not.
fn is_option(&self) -> bool {
false
}
/// Drives the deserialization of a sum value.
///
/// This method will ask the data format ([`A: SumAccess`][SumAccess])
/// which variant of the sum to select in terms of a variant name / tag.
/// `A` will use a [`VariantVisitor`], that `SumVisitor` has provided,
/// to translate into something that is meaningful for `visit_sum`, e.g., an index.
///
/// The data format will also return an object ([`VariantAccess`])
/// that can deserialize the contents of the variant.
fn visit_sum<A: SumAccess<'de>>(self, data: A) -> Result<Self::Output, A::Error>;
}
/// Provides a [`SumVisitor`] access to the data of a sum in the input.
///
/// An `A: SumAccess` object is created by the [`D: Deserializer`]
/// which passes `A` to a [`V: SumVisitor`] that `D` in turn was passed.
/// `A` is then used by `V` to split tag and value input apart.
pub trait SumAccess<'de> {
/// The error type that can be returned if some error occurs during deserialization.
type Error: Error;
/// The visitor used to deserialize the content of the sum variant.
type Variant: VariantAccess<'de, Error = Self::Error>;
/// Called to identify which variant to deserialize.
/// Returns a tuple with the result of identification (`V::Output`)
/// and the input to variant data deserialization.
///
/// The `visitor` is provided by the [`Deserializer`].
/// This method is typically called from [`SumVisitor::visit_sum`]
/// which will provide the [`V: VariantVisitor`](VariantVisitor).
fn variant<V: VariantVisitor>(self, visitor: V) -> Result<(V::Output, Self::Variant), Self::Error>;
}
/// A visitor passed from [`SumVisitor`] to [`SumAccess::variant`]
/// which the latter uses to decide what variant to deserialize.
pub trait VariantVisitor {
/// The result of identifying a variant, e.g., some index type.
type Output;
/// Provides the visitor the chance to add valid names into `names`.
fn variant_names(&self, names: &mut dyn ValidNames);
/// Identify the variant based on `tag`.
fn visit_tag<E: Error>(self, tag: u8) -> Result<Self::Output, E>;
/// Identify the variant based on `name`.
fn visit_name<E: Error>(self, name: &str) -> Result<Self::Output, E>;
}
/// A visitor passed from [`SumAccess`] to [`SumVisitor::visit_sum`]
/// which the latter uses to deserialize the data of a selected variant.
pub trait VariantAccess<'de>: Sized {
type Error: Error;
/// Called when deserializing the contents of a sum variant.
///
/// This method exists as a convenience for [`Deserialize`] implementations.
fn deserialize<T: Deserialize<'de>>(self) -> Result<T, Self::Error> {
self.deserialize_seed(PhantomData)
}
/// Called when deserializing the contents of a sum variant, and provided with a `seed` value.
fn deserialize_seed<T: DeserializeSeed<'de>>(self, seed: T) -> Result<T::Output, Self::Error>;
}
/// A `SliceVisitor` is provided a slice `T` of some elements by a [`Deserializer`]
/// and is tasked with translating this slice to the `Output` type.
pub trait SliceVisitor<'de, T: ToOwned + ?Sized>: Sized {
/// The output produced by this visitor.
type Output;
/// The input contains a slice.
///
/// The lifetime of the slice is ephemeral
/// and it may be destroyed after this method returns.
fn visit<E: Error>(self, slice: &T) -> Result<Self::Output, E>;
/// The input contains a slice and ownership of the slice is being given to the [`SliceVisitor`].
fn visit_owned<E: Error>(self, buf: T::Owned) -> Result<Self::Output, E> {
self.visit(buf.borrow())
}
/// The input contains a slice that lives at least as long (`'de`) as the [`Deserializer`].
fn visit_borrowed<E: Error>(self, borrowed_slice: &'de T) -> Result<Self::Output, E> {
self.visit(borrowed_slice)
}
}
/// A visitor walking through a [`Deserializer`] for arrays.
pub trait ArrayVisitor<'de, T> {
/// The output produced by this visitor.
type Output;
/// The input contains an array.
fn visit<A: ArrayAccess<'de, Element = T>>(self, vec: A) -> Result<Self::Output, A::Error>;
}
/// Provides an [`ArrayVisitor`] with access to each element of the array in the input.
///
/// This is a trait that a [`Deserializer`] passes to an [`ArrayVisitor`] implementation.
pub trait ArrayAccess<'de> {
/// The element / base type of the array.
type Element;
/// The error type that can be returned if some error occurs during deserialization.
type Error: Error;
/// This returns `Ok(Some(value))` for the next element in the array,
/// or `Ok(None)` if there are no more remaining elements.
fn next_element(&mut self) -> Result<Option<Self::Element>, Self::Error>;
/// Returns the number of elements remaining in the array, if known.
fn size_hint(&self) -> Option<usize> {
None
}
}
/// A visitor walking through a [`Deserializer`] for maps.
pub trait MapVisitor<'de, K, V> {
/// The output produced by this visitor.
type Output;
/// The input contains a key-value map.
fn visit<A: MapAccess<'de, Key = K, Value = V>>(self, map: A) -> Result<Self::Output, A::Error>;
}
/// Provides a [`MapVisitor`] with access to each element of the array in the input.
///
/// This is a trait that a [`Deserializer`] passes to a [`MapVisitor`] implementation.
pub trait MapAccess<'de> {
/// The key type of the map.
type Key;
/// The value type of the map.
type Value;
/// The error type that can be returned if some error occurs during deserialization.
type Error: Error;
/// This returns `Ok(Some((key, value)))` for the next (key-value) pair in the map,
/// or `Ok(None)` if there are no more remaining items.
#[allow(clippy::type_complexity)]
fn next_entry(&mut self) -> Result<Option<(Self::Key, Self::Value)>, Self::Error>;
/// Returns the number of elements remaining in the map, if known.
fn size_hint(&self) -> Option<usize> {
None
}
}
impl<'de, A: MapAccess<'de>> ArrayAccess<'de> for A {
type Element = (A::Key, A::Value);
type Error = A::Error;
fn next_element(&mut self) -> Result<Option<Self::Element>, Self::Error> {
self.next_entry()
}
fn size_hint(&self) -> Option<usize> {
self.size_hint()
}
}
/// `DeserializeSeed` is the stateful form of the [`Deserialize`] trait.
pub trait DeserializeSeed<'de> {
/// The type produced by using this seed.
type Output;
/// Equivalent to the more common [`Deserialize::deserialize`] associated function,
/// except with some initial piece of data (the seed `self`) passed in.
fn deserialize<D: Deserializer<'de>>(self, deserializer: D) -> Result<Self::Output, D::Error>;
}
use crate::de::impls::BorrowedSliceVisitor;
pub use spacetimedb_bindings_macro::Deserialize;
/// A **datastructure** that can be deserialized from any data format supported by SATS.
///
/// In most cases, implementations of `Deserialize` may be `#[derive(Deserialize)]`d.
///
/// The `Deserialize` trait in SATS performs the same function as [`serde::Deserialize`] in [`serde`].
/// See the documentation of [`serde::Deserialize`] for more information of the data model.
///
/// The lifetime `'de` allows us to deserialize lifetime-generic types in a zero-copy fashion.
///
/// [`serde::Deserialize`]: ::serde::Deserialize
/// [`serde`]: https://crates.io/crates/serde
pub trait Deserialize<'de>: Sized {
/// Deserialize this value from the given `deserializer`.
fn deserialize<D: Deserializer<'de>>(deserializer: D) -> Result<Self, D::Error>;
/// used in the Deserialize for Vec<T> impl to allow specializing deserializing Vec<T> as bytes
#[doc(hidden)]
#[inline(always)]
fn __deserialize_vec<D: Deserializer<'de>>(deserializer: D) -> Result<Vec<Self>, D::Error> {
deserializer.deserialize_array(BasicVecVisitor)
}
#[doc(hidden)]
#[inline(always)]
fn __deserialize_array<D: Deserializer<'de>, const N: usize>(deserializer: D) -> Result<[Self; N], D::Error> {
deserializer.deserialize_array(BasicArrayVisitor)
}
}
/// A data structure that can be deserialized in SATS
/// without borrowing any data from the deserializer.
pub trait DeserializeOwned: for<'de> Deserialize<'de> {}
impl<T: for<'de> Deserialize<'de>> DeserializeOwned for T {}
impl<'de, T: Deserialize<'de>> DeserializeSeed<'de> for PhantomData<T> {
type Output = T;
fn deserialize<D: Deserializer<'de>>(self, deserializer: D) -> Result<Self::Output, D::Error> {
T::deserialize(deserializer)
}
}
/// A vector with two operations: `with_capacity` and `push`.
pub trait GrowingVec<T> {
/// Create the collection with the given capacity.
fn with_capacity(cap: usize) -> Self;
/// Push to the vector the `elem`.
fn push(&mut self, elem: T);
}
impl<T> GrowingVec<T> for Vec<T> {
fn with_capacity(cap: usize) -> Self {
Self::with_capacity(cap)
}
fn push(&mut self, elem: T) {
self.push(elem)
}
}
impl<T, const N: usize> GrowingVec<T> for SmallVec<[T; N]> {
fn with_capacity(cap: usize) -> Self {
Self::with_capacity(cap)
}
fn push(&mut self, elem: T) {
self.push(elem)
}
}
/// A basic implementation of `ArrayVisitor::visit` using the provided size hint.
pub fn array_visit<'de, A: ArrayAccess<'de>, V: GrowingVec<A::Element>>(mut access: A) -> Result<V, A::Error> {
let mut v = V::with_capacity(access.size_hint().unwrap_or(0));
while let Some(x) = access.next_element()? {
v.push(x)
}
Ok(v)
}
/// An implementation of [`ArrayVisitor<'de, T>`] where the output is a `Vec<T>`.
pub struct BasicVecVisitor;
impl<'de, T> ArrayVisitor<'de, T> for BasicVecVisitor {
type Output = Vec<T>;
fn visit<A: ArrayAccess<'de, Element = T>>(self, vec: A) -> Result<Self::Output, A::Error> {
array_visit(vec)
}
}
/// An implementation of [`ArrayVisitor<'de, T>`] where the output is a `SmallVec<[T; N]>`.
pub struct BasicSmallVecVisitor<const N: usize>;
impl<'de, T, const N: usize> ArrayVisitor<'de, T> for BasicSmallVecVisitor<N> {
type Output = SmallVec<[T; N]>;
fn visit<A: ArrayAccess<'de, Element = T>>(self, vec: A) -> Result<Self::Output, A::Error> {
array_visit(vec)
}
}
/// An implementation of [`MapVisitor<'de, K, V>`] where the output is a `BTreeMap<K, V>`.
pub struct BasicMapVisitor;
impl<'de, K: Ord, V> MapVisitor<'de, K, V> for BasicMapVisitor {
type Output = BTreeMap<K, V>;
fn visit<A: MapAccess<'de, Key = K, Value = V>>(self, map: A) -> Result<Self::Output, A::Error> {
Ok(array_visit::<_, Vec<_>>(map)?.into_iter().collect())
}
}
/// An implementation of [`ArrayVisitor<'de, T>`] where the output is a `[T; N]`.
struct BasicArrayVisitor<const N: usize>;
impl<'de, T, const N: usize> ArrayVisitor<'de, T> for BasicArrayVisitor<N> {
type Output = [T; N];
fn visit<A: ArrayAccess<'de, Element = T>>(self, mut vec: A) -> Result<Self::Output, A::Error> {
let mut v = arrayvec::ArrayVec::<T, N>::new();
while let Some(el) = vec.next_element()? {
v.try_push(el)
.map_err(|_| Error::custom("too many elements for array"))?
}
v.into_inner().map_err(|_| Error::custom("too few elements for array"))
}
}
/// Provided a function `names` that is allowed to store a name into a valid set,
/// returns a human readable list of all the names,
/// or `None` in the case of an empty list of names.
fn one_of_names(names: impl Fn(&mut dyn ValidNames)) -> Option<impl fmt::Display> {
/// An implementation of `ValidNames` that just counts how many valid names are pushed into it.
struct CountNames(usize);
impl ValidNames for CountNames {
fn push(&mut self, _: &str) {
self.0 += 1
}
}
/// An implementation of `ValidNames` that provides a human friendly enumeration of names.
struct OneOfNames<'a, 'b> {
/// A `.push(_)` counter.
index: usize,
/// How many names there were.
count: usize,
/// Result of formatting thus far.
f: Result<&'a mut fmt::Formatter<'b>, fmt::Error>,
}
impl<'a, 'b> OneOfNames<'a, 'b> {
fn new(count: usize, f: &'a mut fmt::Formatter<'b>) -> Self {
Self {
index: 0,
count,
f: Ok(f),
}
}
}
impl ValidNames for OneOfNames<'_, '_> {
fn push(&mut self, name: &str) {
// This will give us, after all `.push()`es have been made, the following:
//
// count = 1 -> "`foo`"
// = 2 -> "`foo` or `bar`"
// > 2 -> "one of `foo`, `bar`, or `baz`"
let Ok(f) = &mut self.f else {
return;
};
self.index += 1;
if let Err(e) = match (self.count, self.index) {
(1, _) => write!(f, "`{name}`"),
(2, 1) => write!(f, "`{name}`"),
(2, 2) => write!(f, "`or `{name}`"),
(_, 1) => write!(f, "one of `{name}`"),
(c, i) if i < c => write!(f, ", `{name}`"),
(_, _) => write!(f, ", `, or {name}`"),
} {
self.f = Err(e);
}
}
}
// Count how many names have been pushed.
let count = CountNames(0).run(&names).0;
// There was at least one name; render those names.
(count != 0).then(|| fmt_fn(move |fmt| OneOfNames::new(count, fmt).run(&names).f.map(drop)))
}