Struct serde::ser::Impossible

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pub struct Impossible<Ok, Error> { /* private fields */ }
Expand description

Helper type for implementing a Serializer that does not support serializing one of the compound types.

This type cannot be instantiated, but implements every one of the traits corresponding to the Serializer compound types: SerializeSeq, SerializeTuple, SerializeTupleStruct, SerializeTupleVariant, SerializeMap, SerializeStruct, and SerializeStructVariant.

impl Serializer for MySerializer {
    type Ok = ();
    type Error = Error;

    type SerializeSeq = Impossible<(), Error>;
    /* other associated types */

    /// This data format does not support serializing sequences.
    fn serialize_seq(self,
                     len: Option<usize>)
                     -> Result<Self::SerializeSeq, Error> {
        // Given Impossible cannot be instantiated, the only
        // thing we can do here is to return an error.
        Err(...)
    }

    /* other Serializer methods */
}

Trait Implementations§

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impl<Ok, Error> SerializeMap for Impossible<Ok, Error>
where Error: Error,

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type Ok = Ok

Must match the Ok type of our Serializer.
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type Error = Error

Must match the Error type of our Serializer.
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fn serialize_key<T>(&mut self, key: &T) -> Result<(), Error>
where T: ?Sized + Serialize,

Serialize a map key. Read more
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fn serialize_value<T>(&mut self, value: &T) -> Result<(), Error>
where T: ?Sized + Serialize,

Serialize a map value. Read more
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fn end(self) -> Result<Ok, Error>

Finish serializing a map.
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fn serialize_entry<K, V>( &mut self, key: &K, value: &V ) -> Result<(), Self::Error>
where K: ?Sized + Serialize, V: ?Sized + Serialize,

Serialize a map entry consisting of a key and a value. Read more
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impl<Ok, Error> SerializeSeq for Impossible<Ok, Error>
where Error: Error,

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type Ok = Ok

Must match the Ok type of our Serializer.
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type Error = Error

Must match the Error type of our Serializer.
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fn serialize_element<T>(&mut self, value: &T) -> Result<(), Error>
where T: ?Sized + Serialize,

Serialize a sequence element.
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fn end(self) -> Result<Ok, Error>

Finish serializing a sequence.
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impl<Ok, Error> SerializeStruct for Impossible<Ok, Error>
where Error: Error,

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type Ok = Ok

Must match the Ok type of our Serializer.
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type Error = Error

Must match the Error type of our Serializer.
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fn serialize_field<T>( &mut self, key: &'static str, value: &T ) -> Result<(), Error>
where T: ?Sized + Serialize,

Serialize a struct field.
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fn end(self) -> Result<Ok, Error>

Finish serializing a struct.
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fn skip_field(&mut self, key: &'static str) -> Result<(), Self::Error>

Indicate that a struct field has been skipped. Read more
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impl<Ok, Error> SerializeStructVariant for Impossible<Ok, Error>
where Error: Error,

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type Ok = Ok

Must match the Ok type of our Serializer.
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type Error = Error

Must match the Error type of our Serializer.
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fn serialize_field<T>( &mut self, key: &'static str, value: &T ) -> Result<(), Error>
where T: ?Sized + Serialize,

Serialize a struct variant field.
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fn end(self) -> Result<Ok, Error>

Finish serializing a struct variant.
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fn skip_field(&mut self, key: &'static str) -> Result<(), Self::Error>

Indicate that a struct variant field has been skipped. Read more
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impl<Ok, Error> SerializeTuple for Impossible<Ok, Error>
where Error: Error,

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type Ok = Ok

Must match the Ok type of our Serializer.
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type Error = Error

Must match the Error type of our Serializer.
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fn serialize_element<T>(&mut self, value: &T) -> Result<(), Error>
where T: ?Sized + Serialize,

Serialize a tuple element.
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fn end(self) -> Result<Ok, Error>

Finish serializing a tuple.
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impl<Ok, Error> SerializeTupleStruct for Impossible<Ok, Error>
where Error: Error,

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type Ok = Ok

Must match the Ok type of our Serializer.
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type Error = Error

Must match the Error type of our Serializer.
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fn serialize_field<T>(&mut self, value: &T) -> Result<(), Error>
where T: ?Sized + Serialize,

Serialize a tuple struct field.
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fn end(self) -> Result<Ok, Error>

Finish serializing a tuple struct.
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impl<Ok, Error> SerializeTupleVariant for Impossible<Ok, Error>
where Error: Error,

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type Ok = Ok

Must match the Ok type of our Serializer.
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type Error = Error

Must match the Error type of our Serializer.
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fn serialize_field<T>(&mut self, value: &T) -> Result<(), Error>
where T: ?Sized + Serialize,

Serialize a tuple variant field.
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fn end(self) -> Result<Ok, Error>

Finish serializing a tuple variant.

Auto Trait Implementations§

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impl<Ok, Error> Freeze for Impossible<Ok, Error>

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impl<Ok, Error> RefUnwindSafe for Impossible<Ok, Error>
where Error: RefUnwindSafe, Ok: RefUnwindSafe,

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impl<Ok, Error> Send for Impossible<Ok, Error>
where Error: Send, Ok: Send,

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impl<Ok, Error> Sync for Impossible<Ok, Error>
where Error: Sync, Ok: Sync,

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impl<Ok, Error> Unpin for Impossible<Ok, Error>
where Error: Unpin, Ok: Unpin,

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impl<Ok, Error> UnwindSafe for Impossible<Ok, Error>
where Error: UnwindSafe, Ok: UnwindSafe,

Blanket Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.