pub struct IgnoredAny;
Expand description
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 serde::de::{
self, Deserialize, DeserializeSeed, Deserializer, IgnoredAny, SeqAccess, Visitor,
};
use std::fmt;
use std::marker::PhantomData;
/// 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§
source§impl Clone for IgnoredAny
impl Clone for IgnoredAny
source§fn clone(&self) -> IgnoredAny
fn clone(&self) -> IgnoredAny
Returns a copy of the value. Read more
1.0.0 · source§fn clone_from(&mut self, source: &Self)
fn clone_from(&mut self, source: &Self)
Performs copy-assignment from
source
. Read moresource§impl Debug for IgnoredAny
impl Debug for IgnoredAny
source§impl Default for IgnoredAny
impl Default for IgnoredAny
source§fn default() -> IgnoredAny
fn default() -> IgnoredAny
Returns the “default value” for a type. Read more
source§impl<'de> Deserialize<'de> for IgnoredAny
impl<'de> Deserialize<'de> for IgnoredAny
source§fn deserialize<D>(
deserializer: D
) -> Result<IgnoredAny, <D as Deserializer<'de>>::Error>where
D: Deserializer<'de>,
fn deserialize<D>( deserializer: D ) -> Result<IgnoredAny, <D as Deserializer<'de>>::Error>where D: Deserializer<'de>,
Deserialize this value from the given Serde deserializer. Read more
source§impl PartialEq<IgnoredAny> for IgnoredAny
impl PartialEq<IgnoredAny> for IgnoredAny
source§fn eq(&self, other: &IgnoredAny) -> bool
fn eq(&self, other: &IgnoredAny) -> bool
This method tests for
self
and other
values to be equal, and is used
by ==
.source§impl<'de> Visitor<'de> for IgnoredAny
impl<'de> Visitor<'de> for IgnoredAny
§type Value = IgnoredAny
type Value = IgnoredAny
The value produced by this visitor.
source§fn expecting(&self, formatter: &mut Formatter<'_>) -> Result<(), Error>
fn expecting(&self, formatter: &mut Formatter<'_>) -> Result<(), Error>
Format a message stating what data this Visitor expects to receive. Read more
source§fn visit_bool<E>(self, x: bool) -> Result<<IgnoredAny as Visitor<'de>>::Value, E>
fn visit_bool<E>(self, x: bool) -> Result<<IgnoredAny as Visitor<'de>>::Value, E>
The input contains a boolean. Read more
source§fn visit_i64<E>(self, x: i64) -> Result<<IgnoredAny as Visitor<'de>>::Value, E>
fn visit_i64<E>(self, x: i64) -> Result<<IgnoredAny as Visitor<'de>>::Value, E>
The input contains an
i64
. Read moresource§fn visit_i128<E>(self, x: i128) -> Result<<IgnoredAny as Visitor<'de>>::Value, E>
fn visit_i128<E>(self, x: i128) -> Result<<IgnoredAny as Visitor<'de>>::Value, E>
The input contains a
i128
. Read moresource§fn visit_u64<E>(self, x: u64) -> Result<<IgnoredAny as Visitor<'de>>::Value, E>
fn visit_u64<E>(self, x: u64) -> Result<<IgnoredAny as Visitor<'de>>::Value, E>
The input contains a
u64
. Read moresource§fn visit_u128<E>(self, x: u128) -> Result<<IgnoredAny as Visitor<'de>>::Value, E>
fn visit_u128<E>(self, x: u128) -> Result<<IgnoredAny as Visitor<'de>>::Value, E>
The input contains a
u128
. Read moresource§fn visit_f64<E>(self, x: f64) -> Result<<IgnoredAny as Visitor<'de>>::Value, E>
fn visit_f64<E>(self, x: f64) -> Result<<IgnoredAny as Visitor<'de>>::Value, E>
The input contains an
f64
. Read moresource§fn visit_str<E>(self, s: &str) -> Result<<IgnoredAny as Visitor<'de>>::Value, E>where
E: Error,
fn visit_str<E>(self, s: &str) -> Result<<IgnoredAny as Visitor<'de>>::Value, E>where E: Error,
The input contains a string. The lifetime of the string is ephemeral and
it may be destroyed after this method returns. Read more
source§fn visit_none<E>(self) -> Result<<IgnoredAny as Visitor<'de>>::Value, E>
fn visit_none<E>(self) -> Result<<IgnoredAny as Visitor<'de>>::Value, E>
The input contains an optional that is absent. Read more
source§fn visit_some<D>(
self,
deserializer: D
) -> Result<<IgnoredAny as Visitor<'de>>::Value, <D as Deserializer<'de>>::Error>where
D: Deserializer<'de>,
fn visit_some<D>( self, deserializer: D ) -> Result<<IgnoredAny as Visitor<'de>>::Value, <D as Deserializer<'de>>::Error>where D: Deserializer<'de>,
The input contains an optional that is present. Read more
source§fn visit_newtype_struct<D>(
self,
deserializer: D
) -> Result<<IgnoredAny as Visitor<'de>>::Value, <D as Deserializer<'de>>::Error>where
D: Deserializer<'de>,
fn visit_newtype_struct<D>( self, deserializer: D ) -> Result<<IgnoredAny as Visitor<'de>>::Value, <D as Deserializer<'de>>::Error>where D: Deserializer<'de>,
The input contains a newtype struct. Read more
source§fn visit_unit<E>(self) -> Result<<IgnoredAny as Visitor<'de>>::Value, E>
fn visit_unit<E>(self) -> Result<<IgnoredAny as Visitor<'de>>::Value, E>
The input contains a unit
()
. Read moresource§fn visit_seq<A>(
self,
seq: A
) -> Result<<IgnoredAny as Visitor<'de>>::Value, <A as SeqAccess<'de>>::Error>where
A: SeqAccess<'de>,
fn visit_seq<A>( self, seq: A ) -> Result<<IgnoredAny as Visitor<'de>>::Value, <A as SeqAccess<'de>>::Error>where A: SeqAccess<'de>,
The input contains a sequence of elements. Read more
source§fn visit_map<A>(
self,
map: A
) -> Result<<IgnoredAny as Visitor<'de>>::Value, <A as MapAccess<'de>>::Error>where
A: MapAccess<'de>,
fn visit_map<A>( self, map: A ) -> Result<<IgnoredAny as Visitor<'de>>::Value, <A as MapAccess<'de>>::Error>where A: MapAccess<'de>,
The input contains a key-value map. Read more
source§fn visit_bytes<E>(
self,
bytes: &[u8]
) -> Result<<IgnoredAny as Visitor<'de>>::Value, E>where
E: Error,
fn visit_bytes<E>( self, bytes: &[u8] ) -> Result<<IgnoredAny as Visitor<'de>>::Value, E>where E: Error,
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
source§fn visit_enum<A>(
self,
data: A
) -> Result<<IgnoredAny as Visitor<'de>>::Value, <A as EnumAccess<'de>>::Error>where
A: EnumAccess<'de>,
fn visit_enum<A>( self, data: A ) -> Result<<IgnoredAny as Visitor<'de>>::Value, <A as EnumAccess<'de>>::Error>where A: EnumAccess<'de>,
The input contains an enum. Read more
source§fn visit_i8<E>(self, v: i8) -> Result<Self::Value, E>where
E: Error,
fn visit_i8<E>(self, v: i8) -> Result<Self::Value, E>where E: Error,
The input contains an
i8
. Read moresource§fn visit_i16<E>(self, v: i16) -> Result<Self::Value, E>where
E: Error,
fn visit_i16<E>(self, v: i16) -> Result<Self::Value, E>where E: Error,
The input contains an
i16
. Read moresource§fn visit_i32<E>(self, v: i32) -> Result<Self::Value, E>where
E: Error,
fn visit_i32<E>(self, v: i32) -> Result<Self::Value, E>where E: Error,
The input contains an
i32
. Read moresource§fn visit_u8<E>(self, v: u8) -> Result<Self::Value, E>where
E: Error,
fn visit_u8<E>(self, v: u8) -> Result<Self::Value, E>where E: Error,
The input contains a
u8
. Read moresource§fn visit_u16<E>(self, v: u16) -> Result<Self::Value, E>where
E: Error,
fn visit_u16<E>(self, v: u16) -> Result<Self::Value, E>where E: Error,
The input contains a
u16
. Read moresource§fn visit_u32<E>(self, v: u32) -> Result<Self::Value, E>where
E: Error,
fn visit_u32<E>(self, v: u32) -> Result<Self::Value, E>where E: Error,
The input contains a
u32
. Read moresource§fn visit_f32<E>(self, v: f32) -> Result<Self::Value, E>where
E: Error,
fn visit_f32<E>(self, v: f32) -> Result<Self::Value, E>where E: Error,
The input contains an
f32
. Read moresource§fn visit_char<E>(self, v: char) -> Result<Self::Value, E>where
E: Error,
fn visit_char<E>(self, v: char) -> Result<Self::Value, E>where E: Error,
The input contains a
char
. Read moresource§fn visit_borrowed_str<E>(self, v: &'de str) -> Result<Self::Value, E>where
E: Error,
fn visit_borrowed_str<E>(self, v: &'de str) -> Result<Self::Value, E>where E: Error,
The input contains a string that lives at least as long as the
Deserializer
. Read moresource§fn visit_string<E>(self, v: String) -> Result<Self::Value, E>where
E: Error,
fn visit_string<E>(self, v: String) -> Result<Self::Value, E>where E: Error,
The input contains a string and ownership of the string is being given
to the
Visitor
. Read moreimpl Copy for IgnoredAny
impl StructuralPartialEq for IgnoredAny
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> Conv for T
impl<T> Conv for T
§impl<T> FmtForward for T
impl<T> FmtForward for T
§fn fmt_binary(self) -> FmtBinary<Self>where
Self: Binary,
fn fmt_binary(self) -> FmtBinary<Self>where Self: Binary,
Causes
self
to use its Binary
implementation when Debug
-formatted.§fn fmt_display(self) -> FmtDisplay<Self>where
Self: Display,
fn fmt_display(self) -> FmtDisplay<Self>where Self: Display,
Causes
self
to use its Display
implementation when
Debug
-formatted.§fn fmt_lower_exp(self) -> FmtLowerExp<Self>where
Self: LowerExp,
fn fmt_lower_exp(self) -> FmtLowerExp<Self>where Self: LowerExp,
Causes
self
to use its LowerExp
implementation when
Debug
-formatted.§fn fmt_lower_hex(self) -> FmtLowerHex<Self>where
Self: LowerHex,
fn fmt_lower_hex(self) -> FmtLowerHex<Self>where Self: LowerHex,
Causes
self
to use its LowerHex
implementation when
Debug
-formatted.§fn fmt_octal(self) -> FmtOctal<Self>where
Self: Octal,
fn fmt_octal(self) -> FmtOctal<Self>where Self: Octal,
Causes
self
to use its Octal
implementation when Debug
-formatted.§fn fmt_pointer(self) -> FmtPointer<Self>where
Self: Pointer,
fn fmt_pointer(self) -> FmtPointer<Self>where Self: Pointer,
Causes
self
to use its Pointer
implementation when
Debug
-formatted.§fn fmt_upper_exp(self) -> FmtUpperExp<Self>where
Self: UpperExp,
fn fmt_upper_exp(self) -> FmtUpperExp<Self>where Self: UpperExp,
Causes
self
to use its UpperExp
implementation when
Debug
-formatted.§fn fmt_upper_hex(self) -> FmtUpperHex<Self>where
Self: UpperHex,
fn fmt_upper_hex(self) -> FmtUpperHex<Self>where Self: UpperHex,
Causes
self
to use its UpperHex
implementation when
Debug
-formatted.§fn fmt_list(self) -> FmtList<Self>where
&'a Self: for<'a> IntoIterator,
fn fmt_list(self) -> FmtList<Self>where &'a Self: for<'a> IntoIterator,
Formats each item in a sequence. Read more
source§impl<T> Instrument for T
impl<T> Instrument for T
source§fn instrument(self, span: Span) -> Instrumented<Self> ⓘ
fn instrument(self, span: Span) -> Instrumented<Self> ⓘ
source§fn in_current_span(self) -> Instrumented<Self> ⓘ
fn in_current_span(self) -> Instrumented<Self> ⓘ
§impl<T> Pipe for Twhere
T: ?Sized,
impl<T> Pipe for Twhere T: ?Sized,
§fn pipe<R>(self, func: impl FnOnce(Self) -> R) -> Rwhere
Self: Sized,
fn pipe<R>(self, func: impl FnOnce(Self) -> R) -> Rwhere Self: Sized,
Pipes by value. This is generally the method you want to use. Read more
§fn pipe_ref<'a, R>(&'a self, func: impl FnOnce(&'a Self) -> R) -> Rwhere
R: 'a,
fn pipe_ref<'a, R>(&'a self, func: impl FnOnce(&'a Self) -> R) -> Rwhere R: 'a,
Borrows
self
and passes that borrow into the pipe function. Read more§fn pipe_ref_mut<'a, R>(&'a mut self, func: impl FnOnce(&'a mut Self) -> R) -> Rwhere
R: 'a,
fn pipe_ref_mut<'a, R>(&'a mut self, func: impl FnOnce(&'a mut Self) -> R) -> Rwhere R: 'a,
Mutably borrows
self
and passes that borrow into the pipe function. Read more§fn pipe_borrow<'a, B, R>(&'a self, func: impl FnOnce(&'a B) -> R) -> Rwhere
Self: Borrow<B>,
B: 'a + ?Sized,
R: 'a,
fn pipe_borrow<'a, B, R>(&'a self, func: impl FnOnce(&'a B) -> R) -> Rwhere Self: Borrow<B>, B: 'a + ?Sized, R: 'a,
§fn pipe_borrow_mut<'a, B, R>(
&'a mut self,
func: impl FnOnce(&'a mut B) -> R
) -> Rwhere
Self: BorrowMut<B>,
B: 'a + ?Sized,
R: 'a,
fn pipe_borrow_mut<'a, B, R>( &'a mut self, func: impl FnOnce(&'a mut B) -> R ) -> Rwhere Self: BorrowMut<B>, B: 'a + ?Sized, R: 'a,
§fn pipe_as_ref<'a, U, R>(&'a self, func: impl FnOnce(&'a U) -> R) -> Rwhere
Self: AsRef<U>,
U: 'a + ?Sized,
R: 'a,
fn pipe_as_ref<'a, U, R>(&'a self, func: impl FnOnce(&'a U) -> R) -> Rwhere Self: AsRef<U>, U: 'a + ?Sized, R: 'a,
Borrows
self
, then passes self.as_ref()
into the pipe function.§fn pipe_as_mut<'a, U, R>(&'a mut self, func: impl FnOnce(&'a mut U) -> R) -> Rwhere
Self: AsMut<U>,
U: 'a + ?Sized,
R: 'a,
fn pipe_as_mut<'a, U, R>(&'a mut self, func: impl FnOnce(&'a mut U) -> R) -> Rwhere Self: AsMut<U>, U: 'a + ?Sized, R: 'a,
Mutably borrows
self
, then passes self.as_mut()
into the pipe
function.§impl<T> Tap for T
impl<T> Tap for T
§fn tap_borrow<B>(self, func: impl FnOnce(&B)) -> Selfwhere
Self: Borrow<B>,
B: ?Sized,
fn tap_borrow<B>(self, func: impl FnOnce(&B)) -> Selfwhere Self: Borrow<B>, B: ?Sized,
Immutable access to the
Borrow<B>
of a value. Read more§fn tap_borrow_mut<B>(self, func: impl FnOnce(&mut B)) -> Selfwhere
Self: BorrowMut<B>,
B: ?Sized,
fn tap_borrow_mut<B>(self, func: impl FnOnce(&mut B)) -> Selfwhere Self: BorrowMut<B>, B: ?Sized,
Mutable access to the
BorrowMut<B>
of a value. Read more§fn tap_ref<R>(self, func: impl FnOnce(&R)) -> Selfwhere
Self: AsRef<R>,
R: ?Sized,
fn tap_ref<R>(self, func: impl FnOnce(&R)) -> Selfwhere Self: AsRef<R>, R: ?Sized,
Immutable access to the
AsRef<R>
view of a value. Read more§fn tap_ref_mut<R>(self, func: impl FnOnce(&mut R)) -> Selfwhere
Self: AsMut<R>,
R: ?Sized,
fn tap_ref_mut<R>(self, func: impl FnOnce(&mut R)) -> Selfwhere Self: AsMut<R>, R: ?Sized,
Mutable access to the
AsMut<R>
view of a value. Read more§fn tap_deref<T>(self, func: impl FnOnce(&T)) -> Selfwhere
Self: Deref<Target = T>,
T: ?Sized,
fn tap_deref<T>(self, func: impl FnOnce(&T)) -> Selfwhere Self: Deref<Target = T>, T: ?Sized,
Immutable access to the
Deref::Target
of a value. Read more§fn tap_deref_mut<T>(self, func: impl FnOnce(&mut T)) -> Selfwhere
Self: DerefMut<Target = T> + Deref,
T: ?Sized,
fn tap_deref_mut<T>(self, func: impl FnOnce(&mut T)) -> Selfwhere Self: DerefMut<Target = T> + Deref, T: ?Sized,
Mutable access to the
Deref::Target
of a value. Read more§fn tap_dbg(self, func: impl FnOnce(&Self)) -> Self
fn tap_dbg(self, func: impl FnOnce(&Self)) -> Self
Calls
.tap()
only in debug builds, and is erased in release builds.§fn tap_mut_dbg(self, func: impl FnOnce(&mut Self)) -> Self
fn tap_mut_dbg(self, func: impl FnOnce(&mut Self)) -> Self
Calls
.tap_mut()
only in debug builds, and is erased in release
builds.§fn tap_borrow_dbg<B>(self, func: impl FnOnce(&B)) -> Selfwhere
Self: Borrow<B>,
B: ?Sized,
fn tap_borrow_dbg<B>(self, func: impl FnOnce(&B)) -> Selfwhere Self: Borrow<B>, B: ?Sized,
Calls
.tap_borrow()
only in debug builds, and is erased in release
builds.§fn tap_borrow_mut_dbg<B>(self, func: impl FnOnce(&mut B)) -> Selfwhere
Self: BorrowMut<B>,
B: ?Sized,
fn tap_borrow_mut_dbg<B>(self, func: impl FnOnce(&mut B)) -> Selfwhere Self: BorrowMut<B>, B: ?Sized,
Calls
.tap_borrow_mut()
only in debug builds, and is erased in release
builds.§fn tap_ref_dbg<R>(self, func: impl FnOnce(&R)) -> Selfwhere
Self: AsRef<R>,
R: ?Sized,
fn tap_ref_dbg<R>(self, func: impl FnOnce(&R)) -> Selfwhere Self: AsRef<R>, R: ?Sized,
Calls
.tap_ref()
only in debug builds, and is erased in release
builds.§fn tap_ref_mut_dbg<R>(self, func: impl FnOnce(&mut R)) -> Selfwhere
Self: AsMut<R>,
R: ?Sized,
fn tap_ref_mut_dbg<R>(self, func: impl FnOnce(&mut R)) -> Selfwhere Self: AsMut<R>, R: ?Sized,
Calls
.tap_ref_mut()
only in debug builds, and is erased in release
builds.§impl<T> TryConv for T
impl<T> TryConv for T
§impl<S, T> UncheckedInto<T> for Swhere
T: UncheckedFrom<S>,
impl<S, T> UncheckedInto<T> for Swhere T: UncheckedFrom<S>,
§fn unchecked_into(self) -> T
fn unchecked_into(self) -> T
The counterpart to
unchecked_from
.