# Struct serde::de::IgnoredAny [−] [src]

    pub struct 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.

ⓘ

    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` [src]

#### `fn clone(&self) -> IgnoredAny` [src]

Returns a copy of the value. Read more

#### `pub fn clone_from(&mut self, source: &Self)`1.0.0 [src]

Performs copy-assignment from `source`. Read more

### `impl Copy for IgnoredAny` [src]

### `impl Debug for IgnoredAny` [src]

#### `fn fmt(&self, f: &mut Formatter<'_>) -> Result` [src]

Formats the value using the given formatter. Read more

### `impl Default for IgnoredAny` [src]

#### `fn default() -> IgnoredAny` [src]

Returns the “default value” for a type. Read more

### `impl<'de> Deserialize<'de> for IgnoredAny` [src]

#### `fn deserialize<D>(deserializer: D) -> Result<IgnoredAny, D::Error> where
D: Deserializer<'de>,` [src]

Deserialize this value from the given Serde deserializer. Read more

### `impl<'de> Visitor<'de> for IgnoredAny` [src]

#### `type Value = IgnoredAny`

The value produced by this visitor.

#### `fn expecting(&self, formatter: &mut Formatter<'_>) -> Result` [src]

Format a message stating what data this Visitor expects to receive. Read more

#### `fn visit_bool<E>(self, x: bool) -> Result<Self::Value, E>` [src]

The input contains a boolean. Read more

#### `fn visit_i64<E>(self, x: i64) -> Result<Self::Value, E>` [src]

The input contains an `i64`. Read more

#### `fn visit_i128<E>(self, x: i128) -> Result<Self::Value, E>` [src]

The input contains a `i128`. Read more

#### `fn visit_u64<E>(self, x: u64) -> Result<Self::Value, E>` [src]

The input contains a `u64`. Read more

#### `fn visit_u128<E>(self, x: u128) -> Result<Self::Value, E>` [src]

The input contains a `u128`. Read more

#### `fn visit_f64<E>(self, x: f64) -> Result<Self::Value, E>` [src]

The input contains an `f64`. Read more

#### `fn visit_str<E>(self, s: &str) -> Result<Self::Value, E> where
E: Error,` [src]

The input contains a string. The lifetime of the string is ephemeral and it may be destroyed after this method returns. Read more

#### `fn visit_none<E>(self) -> Result<Self::Value, E>` [src]

The input contains an optional that is absent. Read more

#### `fn visit_some<D>(self, deserializer: D) -> Result<Self::Value, D::Error> where
D: Deserializer<'de>,` [src]

The input contains an optional that is present. Read more

#### `fn visit_newtype_struct<D>(
self,
deserializer: D
) -> Result<Self::Value, D::Error> where
D: Deserializer<'de>,` [src]

The input contains a newtype struct. Read more

#### `fn visit_unit<E>(self) -> Result<Self::Value, E>` [src]

The input contains a unit `()`. Read more

#### `fn visit_seq<A>(self, seq: A) -> Result<Self::Value, A::Error> where
A: SeqAccess<'de>,` [src]

The input contains a sequence of elements. Read more

#### `fn visit_map<A>(self, map: A) -> Result<Self::Value, A::Error> where
A: MapAccess<'de>,` [src]

The input contains a key-value map. Read more

#### `fn visit_bytes<E>(self, bytes: &[u8]) -> Result<Self::Value, E> where
E: Error,` [src]

The input contains a byte array. The lifetime of the byte array is ephemeral and it may be destroyed after this method returns. Read more

#### `fn visit_enum<A>(self, data: A) -> Result<Self::Value, A::Error> where
A: EnumAccess<'de>,` [src]

The input contains an enum. Read more

#### `fn visit_i8<E>(self, v: i8) -> Result<Self::Value, E> where
E: Error,` [src]

The input contains an `i8`. Read more

#### `fn visit_i16<E>(self, v: i16) -> Result<Self::Value, E> where
E: Error,` [src]

The input contains an `i16`. Read more

#### `fn visit_i32<E>(self, v: i32) -> Result<Self::Value, E> where
E: Error,` [src]

The input contains an `i32`. Read more

#### `fn visit_u8<E>(self, v: u8) -> Result<Self::Value, E> where
E: Error,` [src]

The input contains a `u8`. Read more

#### `fn visit_u16<E>(self, v: u16) -> Result<Self::Value, E> where
E: Error,` [src]

The input contains a `u16`. Read more

#### `fn visit_u32<E>(self, v: u32) -> Result<Self::Value, E> where
E: Error,` [src]

The input contains a `u32`. Read more

#### `fn visit_f32<E>(self, v: f32) -> Result<Self::Value, E> where
E: Error,` [src]

The input contains an `f32`. Read more

#### `fn visit_char<E>(self, v: char) -> Result<Self::Value, E> where
E: Error,` [src]

The input contains a `char`. Read more

#### `fn visit_borrowed_str<E>(self, v: &'de str) -> Result<Self::Value, E> where
E: Error,` [src]

The input contains a string that lives at least as long as the `Deserializer`. Read more

#### `fn visit_string<E>(self, v: String) -> Result<Self::Value, E> where
E: Error,` [src]

The input contains a string and ownership of the string is being given to the `Visitor`. Read more

#### `fn visit_borrowed_bytes<E>(self, v: &'de [u8]) -> Result<Self::Value, E> where
E: Error,` [src]

The input contains a byte array that lives at least as long as the `Deserializer`. Read more

#### `fn visit_byte_buf<E>(self, v: Vec<u8>) -> Result<Self::Value, E> where
E: Error,` [src]

The input contains a byte array and ownership of the byte array is being given to the `Visitor`. Read more

## 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,` [src]

#### `pub fn type_id(&self) -> TypeId` [src]

Gets the `TypeId` of `self`. Read more

### `impl<T> Borrow<T> for T where
T: ?Sized,` [src]

#### `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;`
` [src]

Immutably borrows from an owned value. Read more

### `impl<T> BorrowMut<T> for T where
T: ?Sized,` [src]

#### `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;`
` [src]

Mutably borrows from an owned value. Read more

### `impl<T> DeserializeOwned for T where
T: for<'de> Deserialize<'de>,` [src]

### `impl<'de, T> Expected for T where
T: Visitor<'de>,` [src]

#### `pub fn fmt(&Self, &mut Formatter<'_>) -> Result<(), Error>` [src]

Format an explanation of what data was being expected. Same signature as the `Display` and `Debug` traits. Read more

### `impl<T> From<T> for T` [src]

#### `pub fn from(t: T) -> T` [src]

Performs the conversion.

### `impl<T, U> Into<U> for T where
U: From<T>,` [src]

#### `pub fn into(self) -> U` [src]

Performs the conversion.

### `impl<T> ToOwned for T where
T: Clone,` [src]

#### `type Owned = T`

The resulting type after obtaining ownership.

#### `pub fn to_owned(&self) -> T` [src]

Creates owned data from borrowed data, usually by cloning. Read more

#### `pub fn clone_into(&self, target: &mut T)` [src]

🔬 This is a nightly-only experimental API. (`toowned_clone_into`)

recently added

Uses borrowed data to replace owned data, usually by cloning. Read more

### `impl<T, U> TryFrom<U> for T where
U: Into<T>,` [src]

#### `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>` [src]

Performs the conversion.

### `impl<T, U> TryInto<U> for T where
U: TryFrom<T>,` [src]

#### `type Error = <U as TryFrom<T>>::Error`

The type returned in the event of a conversion error.

#### `pub fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>` [src]

Performs the conversion.