Trait serde::de::MapVisitor

pub trait MapVisitor {
    type Error: Error;
    fn visit_key_seed<K>(
        &mut self, 
        seed: K
    ) -> Result<Option<K::Value>, Self::Error>
    where
        K: DeserializeSeed;
    fn visit_value_seed<V>(&mut self, seed: V) -> Result<V::Value, Self::Error>
    where
        V: DeserializeSeed;

    fn visit_seed<K, V>(
        &mut self, 
        kseed: K, 
        vseed: V
    ) -> Result<Option<(K::Value, V::Value)>, Self::Error>
    where
        K: DeserializeSeed,
        V: DeserializeSeed,
    { ... }
    fn visit_key<K>(&mut self) -> Result<Option<K>, Self::Error>
    where
        K: Deserialize,
    { ... }
    fn visit_value<V>(&mut self) -> Result<V, Self::Error>
    where
        V: Deserialize,
    { ... }
    fn visit<K, V>(&mut self) -> Result<Option<(K, V)>, Self::Error>
    where
        K: Deserialize,
        V: Deserialize,
    { ... }
    fn size_hint(&self) -> (usize, Option<usize>) { ... }
}

MapVisitor visits each item in a sequence.

This is a trait that a Deserializer passes to a Visitor implementation.

Associated Types

type Error: Error

The error type that can be returned if some error occurs during deserialization.

Required Methods

fn visit_key_seed<K>(
    &mut self,
    seed: K
) -> Result<Option<K::Value>, Self::Error> where
    K: DeserializeSeed, 

This returns Ok(Some(key)) for the next key in the map, or Ok(None) if there are no more remaining entries.

Deserialize implementations should typically use MapVisitor::visit_key or MapVisitor::visit instead.

fn visit_value_seed<V>(&mut self, seed: V) -> Result<V::Value, Self::Error> where
    V: DeserializeSeed, 

This returns a Ok(value) for the next value in the map.

Deserialize implementations should typically use MapVisitor::visit_value instead.

Provided Methods

fn visit_seed<K, V>(
    &mut self,
    kseed: K,
    vseed: V
) -> Result<Option<(K::Value, V::Value)>, Self::Error> where
    K: DeserializeSeed,
    V: DeserializeSeed, 

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.

MapVisitor implementations should override the default behavior if a more efficient implementation is possible.

Deserialize implementations should typically use MapVisitor::visit instead.

fn visit_key<K>(&mut self) -> Result<Option<K>, Self::Error> where
    K: Deserialize, 

This returns Ok(Some(key)) for the next key in the map, or Ok(None) if there are no more remaining entries.

This method exists as a convenience for Deserialize implementations. MapVisitor implementations should not override the default behavior.

fn visit_value<V>(&mut self) -> Result<V, Self::Error> where
    V: Deserialize, 

This returns a Ok(value) for the next value in the map.

This method exists as a convenience for Deserialize implementations. MapVisitor implementations should not override the default behavior.

fn visit<K, V>(&mut self) -> Result<Option<(K, V)>, Self::Error> where
    K: Deserialize,
    V: Deserialize, 

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.

This method exists as a convenience for Deserialize implementations. MapVisitor implementations should not override the default behavior.

fn size_hint(&self) -> (usize, Option<usize>)

Return the lower and upper bound of items remaining in the sequence.

Implementors

• impl<I, E> MapVisitor for MapDeserializer<I, E> where
    I: Iterator,
    I::Item: Pair,
    <I::Item as Pair>::First: ValueDeserializer<E>,
    <I::Item as Pair>::Second: ValueDeserializer<E>,
    E: Error, 
• impl<'a, V_> MapVisitor for &'a mut V_ where
    V_: MapVisitor,