Trait serde::ser::SerializeMap
source · [−]pub trait SerializeMap {
type Ok;
type Error: Error;
fn serialize_key<T: ?Sized>(&mut self, key: &T) -> Result<(), Self::Error>
where
T: Serialize;
fn serialize_value<T: ?Sized>(
&mut self,
value: &T
) -> Result<(), Self::Error>
where
T: Serialize;
fn end(self) -> Result<Self::Ok, Self::Error>;
fn serialize_entry<K: ?Sized, V: ?Sized>(
&mut self,
key: &K,
value: &V
) -> Result<(), Self::Error>
where
K: Serialize,
V: Serialize,
{ ... }
}
Expand description
Returned from Serializer::serialize_map
.
Example use
use serde::ser::{Serialize, SerializeMap, Serializer};
impl<K, V> Serialize for HashMap<K, V>
where
K: Serialize,
V: Serialize,
{
fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
where
S: Serializer,
{
let mut map = serializer.serialize_map(Some(self.len()))?;
for (k, v) in self {
map.serialize_entry(k, v)?;
}
map.end()
}
}
Example implementation
The example data format presented on the website demonstrates an
implementation of SerializeMap
for a basic JSON data format.
Required Associated Types
Required Methods
Serialize a map key.
If possible, Serialize
implementations are encouraged to use
serialize_entry
instead as it may be implemented more efficiently in
some formats compared to a pair of calls to serialize_key
and
serialize_value
.
Serialize a map value.
Panics
Calling serialize_value
before serialize_key
is incorrect and is
allowed to panic or produce bogus results.
Provided Methods
Serialize a map entry consisting of a key and a value.
Some Serialize
types are not able to hold a key and value in memory
at the same time so SerializeMap
implementations are required to
support serialize_key
and serialize_value
individually. The
serialize_entry
method allows serializers to optimize for the case
where key and value are both available. Serialize
implementations
are encouraged to use serialize_entry
if possible.
The default implementation delegates to serialize_key
and
serialize_value
. This is appropriate for serializers that do not
care about performance or are not able to optimize serialize_entry
any
better than this.