[−][src]Struct serde::de::IgnoredAny
An efficient way of discarding data from a deserializer.
Think of this like serde_json::Value
in that it can be deserialized from
any type, except that it does not store any information about the data that
gets deserialized.
ⓘThis code runs with edition 2018
use std::fmt; use std::marker::PhantomData; use serde::de::{ self, Deserialize, DeserializeSeed, Deserializer, IgnoredAny, SeqAccess, Visitor, }; /// A seed that can be used to deserialize only the `n`th element of a sequence /// while efficiently discarding elements of any type before or after index `n`. /// /// For example to deserialize only the element at index 3: /// /// ``` /// NthElement::new(3).deserialize(deserializer) /// ``` pub struct NthElement<T> { n: usize, marker: PhantomData<T>, } impl<T> NthElement<T> { pub fn new(n: usize) -> Self { NthElement { n: n, marker: PhantomData, } } } impl<'de, T> Visitor<'de> for NthElement<T> where T: Deserialize<'de>, { type Value = T; fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result { write!( formatter, "a sequence in which we care about element {}", self.n ) } fn visit_seq<A>(self, mut seq: A) -> Result<Self::Value, A::Error> where A: SeqAccess<'de>, { // Skip over the first `n` elements. for i in 0..self.n { // It is an error if the sequence ends before we get to element `n`. if seq.next_element::<IgnoredAny>()?.is_none() { return Err(de::Error::invalid_length(i, &self)); } } // Deserialize the one we care about. let nth = match seq.next_element()? { Some(nth) => nth, None => { return Err(de::Error::invalid_length(self.n, &self)); } }; // Skip over any remaining elements in the sequence after `n`. while let Some(IgnoredAny) = seq.next_element()? { // ignore } Ok(nth) } } impl<'de, T> DeserializeSeed<'de> for NthElement<T> where T: Deserialize<'de>, { type Value = T; fn deserialize<D>(self, deserializer: D) -> Result<Self::Value, D::Error> where D: Deserializer<'de>, { deserializer.deserialize_seq(self) } } // Deserialize only the sequence element at index 3 from this deserializer. // The element at index 3 is required to be a string. Elements before and // after index 3 are allowed to be of any type. let s: String = NthElement::new(3).deserialize(deserializer)?;
Trait Implementations
impl Clone for IgnoredAny
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pub fn clone(&self) -> IgnoredAny
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pub fn clone_from(&mut self, source: &Self)
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impl Copy for IgnoredAny
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impl Debug for IgnoredAny
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impl Default for IgnoredAny
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pub fn default() -> IgnoredAny
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impl<'de> Deserialize<'de> for IgnoredAny
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pub fn deserialize<D>(deserializer: D) -> Result<IgnoredAny, D::Error> where
D: Deserializer<'de>,
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D: Deserializer<'de>,
impl<'de> Visitor<'de> for IgnoredAny
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type Value = IgnoredAny
The value produced by this visitor.
pub fn expecting(&self, formatter: &mut Formatter<'_>) -> Result
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pub fn visit_bool<E>(self, x: bool) -> Result<Self::Value, E>
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pub fn visit_i64<E>(self, x: i64) -> Result<Self::Value, E>
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pub fn visit_u64<E>(self, x: u64) -> Result<Self::Value, E>
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pub fn visit_f64<E>(self, x: f64) -> Result<Self::Value, E>
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pub fn visit_str<E>(self, s: &str) -> Result<Self::Value, E> where
E: Error,
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E: Error,
pub fn visit_none<E>(self) -> Result<Self::Value, E>
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pub fn visit_some<D>(self, deserializer: D) -> Result<Self::Value, D::Error> where
D: Deserializer<'de>,
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D: Deserializer<'de>,
pub fn visit_newtype_struct<D>(
self,
deserializer: D
) -> Result<Self::Value, D::Error> where
D: Deserializer<'de>,
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self,
deserializer: D
) -> Result<Self::Value, D::Error> where
D: Deserializer<'de>,
pub fn visit_unit<E>(self) -> Result<Self::Value, E>
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pub fn visit_seq<A>(self, seq: A) -> Result<Self::Value, A::Error> where
A: SeqAccess<'de>,
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A: SeqAccess<'de>,
pub fn visit_map<A>(self, map: A) -> Result<Self::Value, A::Error> where
A: MapAccess<'de>,
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A: MapAccess<'de>,
pub fn visit_bytes<E>(self, bytes: &[u8]) -> Result<Self::Value, E> where
E: Error,
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E: Error,
pub fn visit_enum<A>(self, data: A) -> Result<Self::Value, A::Error> where
A: EnumAccess<'de>,
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A: EnumAccess<'de>,
pub fn visit_i8<E>(self, v: i8) -> Result<Self::Value, E> where
E: Error,
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E: Error,
pub fn visit_i16<E>(self, v: i16) -> Result<Self::Value, E> where
E: Error,
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E: Error,
pub fn visit_i32<E>(self, v: i32) -> Result<Self::Value, E> where
E: Error,
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E: Error,
pub fn visit_i128<E>(self, v: i128) -> Result<Self::Value, E> where
E: Error,
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E: Error,
pub fn visit_u8<E>(self, v: u8) -> Result<Self::Value, E> where
E: Error,
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E: Error,
pub fn visit_u16<E>(self, v: u16) -> Result<Self::Value, E> where
E: Error,
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E: Error,
pub fn visit_u32<E>(self, v: u32) -> Result<Self::Value, E> where
E: Error,
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E: Error,
pub fn visit_u128<E>(self, v: u128) -> Result<Self::Value, E> where
E: Error,
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E: Error,
pub fn visit_f32<E>(self, v: f32) -> Result<Self::Value, E> where
E: Error,
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E: Error,
pub fn visit_char<E>(self, v: char) -> Result<Self::Value, E> where
E: Error,
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E: Error,
pub fn visit_borrowed_str<E>(self, v: &'de str) -> Result<Self::Value, E> where
E: Error,
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E: Error,
pub fn visit_string<E>(self, v: String) -> Result<Self::Value, E> where
E: Error,
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E: Error,
pub fn visit_borrowed_bytes<E>(self, v: &'de [u8]) -> Result<Self::Value, E> where
E: Error,
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E: Error,
pub fn visit_byte_buf<E>(self, v: Vec<u8>) -> Result<Self::Value, E> where
E: Error,
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E: Error,
Auto Trait Implementations
impl RefUnwindSafe for IgnoredAny
impl Send for IgnoredAny
impl Sync for IgnoredAny
impl Unpin for IgnoredAny
impl UnwindSafe for IgnoredAny
Blanket Implementations
impl<T> Any for T where
T: 'static + ?Sized,
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T: 'static + ?Sized,
impl<T> Borrow<T> for T where
T: ?Sized,
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T: ?Sized,
pub fn borrow(&self) -> &TⓘNotable traits for &'_ mut R
impl<'_, R> Read for &'_ mut R where
R: Read + ?Sized, impl<'_, W> Write for &'_ mut W where
W: Write + ?Sized, impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized, type Output = <F as Future>::Output;impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;
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Notable traits for &'_ mut R
impl<'_, R> Read for &'_ mut R where
R: Read + ?Sized, impl<'_, W> Write for &'_ mut W where
W: Write + ?Sized, impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized, type Output = <F as Future>::Output;impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;
impl<T> BorrowMut<T> for T where
T: ?Sized,
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T: ?Sized,
pub fn borrow_mut(&mut self) -> &mut TⓘNotable traits for &'_ mut R
impl<'_, R> Read for &'_ mut R where
R: Read + ?Sized, impl<'_, W> Write for &'_ mut W where
W: Write + ?Sized, impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized, type Output = <F as Future>::Output;impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;
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Notable traits for &'_ mut R
impl<'_, R> Read for &'_ mut R where
R: Read + ?Sized, impl<'_, W> Write for &'_ mut W where
W: Write + ?Sized, impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized, type Output = <F as Future>::Output;impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;
impl<T> DeserializeOwned for T where
T: for<'de> Deserialize<'de>,
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T: for<'de> Deserialize<'de>,
impl<'de, T> Expected for T where
T: Visitor<'de>,
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T: Visitor<'de>,
impl<T> From<T> for T
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impl<T, U> Into<U> for T where
U: From<T>,
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U: From<T>,
impl<T> ToOwned for T where
T: Clone,
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T: Clone,
type Owned = T
The resulting type after obtaining ownership.
pub fn to_owned(&self) -> T
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pub fn clone_into(&self, target: &mut T)
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impl<T, U> TryFrom<U> for T where
U: Into<T>,
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U: Into<T>,
type Error = Infallible
The type returned in the event of a conversion error.
pub fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
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impl<T, U> TryInto<U> for T where
U: TryFrom<T>,
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U: TryFrom<T>,