Trait Serializer

pub trait Serializer {
    type Error: Error;
    type SeqState;
    type TupleState;
    type TupleStructState;
    type TupleVariantState;
    type MapState;
    type StructState;
    type StructVariantState;

    // Required methods
    fn serialize_bool(&mut self, v: bool) -> Result<(), Self::Error>;
    fn serialize_isize(&mut self, v: isize) -> Result<(), Self::Error>;
    fn serialize_i8(&mut self, v: i8) -> Result<(), Self::Error>;
    fn serialize_i16(&mut self, v: i16) -> Result<(), Self::Error>;
    fn serialize_i32(&mut self, v: i32) -> Result<(), Self::Error>;
    fn serialize_i64(&mut self, v: i64) -> Result<(), Self::Error>;
    fn serialize_usize(&mut self, v: usize) -> Result<(), Self::Error>;
    fn serialize_u8(&mut self, v: u8) -> Result<(), Self::Error>;
    fn serialize_u16(&mut self, v: u16) -> Result<(), Self::Error>;
    fn serialize_u32(&mut self, v: u32) -> Result<(), Self::Error>;
    fn serialize_u64(&mut self, v: u64) -> Result<(), Self::Error>;
    fn serialize_f32(&mut self, v: f32) -> Result<(), Self::Error>;
    fn serialize_f64(&mut self, v: f64) -> Result<(), Self::Error>;
    fn serialize_char(&mut self, v: char) -> Result<(), Self::Error>;
    fn serialize_str(&mut self, value: &str) -> Result<(), Self::Error>;
    fn serialize_bytes(&mut self, value: &[u8]) -> Result<(), Self::Error>;
    fn serialize_unit(&mut self) -> Result<(), Self::Error>;
    fn serialize_unit_struct(
        &mut self,
        name: &'static str,
    ) -> Result<(), Self::Error>;
    fn serialize_unit_variant(
        &mut self,
        name: &'static str,
        variant_index: usize,
        variant: &'static str,
    ) -> Result<(), Self::Error>;
    fn serialize_newtype_struct<T>(
        &mut self,
        name: &'static str,
        value: T,
    ) -> Result<(), Self::Error>
       where T: Serialize;
    fn serialize_newtype_variant<T>(
        &mut self,
        name: &'static str,
        variant_index: usize,
        variant: &'static str,
        value: T,
    ) -> Result<(), Self::Error>
       where T: Serialize;
    fn serialize_none(&mut self) -> Result<(), Self::Error>;
    fn serialize_some<T>(&mut self, value: T) -> Result<(), Self::Error>
       where T: Serialize;
    fn serialize_seq(
        &mut self,
        len: Option<usize>,
    ) -> Result<Self::SeqState, Self::Error>;
    fn serialize_seq_elt<T>(
        &mut self,
        state: &mut Self::SeqState,
        value: T,
    ) -> Result<(), Self::Error>
       where T: Serialize;
    fn serialize_seq_end(
        &mut self,
        state: Self::SeqState,
    ) -> Result<(), Self::Error>;
    fn serialize_seq_fixed_size(
        &mut self,
        size: usize,
    ) -> Result<Self::SeqState, Self::Error>;
    fn serialize_tuple(
        &mut self,
        len: usize,
    ) -> Result<Self::TupleState, Self::Error>;
    fn serialize_tuple_elt<T>(
        &mut self,
        state: &mut Self::TupleState,
        value: T,
    ) -> Result<(), Self::Error>
       where T: Serialize;
    fn serialize_tuple_end(
        &mut self,
        state: Self::TupleState,
    ) -> Result<(), Self::Error>;
    fn serialize_tuple_struct(
        &mut self,
        name: &'static str,
        len: usize,
    ) -> Result<Self::TupleStructState, Self::Error>;
    fn serialize_tuple_struct_elt<T>(
        &mut self,
        state: &mut Self::TupleStructState,
        value: T,
    ) -> Result<(), Self::Error>
       where T: Serialize;
    fn serialize_tuple_struct_end(
        &mut self,
        state: Self::TupleStructState,
    ) -> Result<(), Self::Error>;
    fn serialize_tuple_variant(
        &mut self,
        name: &'static str,
        variant_index: usize,
        variant: &'static str,
        len: usize,
    ) -> Result<Self::TupleVariantState, Self::Error>;
    fn serialize_tuple_variant_elt<T>(
        &mut self,
        state: &mut Self::TupleVariantState,
        value: T,
    ) -> Result<(), Self::Error>
       where T: Serialize;
    fn serialize_tuple_variant_end(
        &mut self,
        state: Self::TupleVariantState,
    ) -> Result<(), Self::Error>;
    fn serialize_map(
        &mut self,
        len: Option<usize>,
    ) -> Result<Self::MapState, Self::Error>;
    fn serialize_map_key<T>(
        &mut self,
        state: &mut Self::MapState,
        key: T,
    ) -> Result<(), Self::Error>
       where T: Serialize;
    fn serialize_map_value<T>(
        &mut self,
        state: &mut Self::MapState,
        value: T,
    ) -> Result<(), Self::Error>
       where T: Serialize;
    fn serialize_map_end(
        &mut self,
        state: Self::MapState,
    ) -> Result<(), Self::Error>;
    fn serialize_struct(
        &mut self,
        name: &'static str,
        len: usize,
    ) -> Result<Self::StructState, Self::Error>;
    fn serialize_struct_elt<V>(
        &mut self,
        state: &mut Self::StructState,
        key: &'static str,
        value: V,
    ) -> Result<(), Self::Error>
       where V: Serialize;
    fn serialize_struct_end(
        &mut self,
        state: Self::StructState,
    ) -> Result<(), Self::Error>;
    fn serialize_struct_variant(
        &mut self,
        name: &'static str,
        variant_index: usize,
        variant: &'static str,
        len: usize,
    ) -> Result<Self::StructVariantState, Self::Error>;
    fn serialize_struct_variant_elt<V>(
        &mut self,
        state: &mut Self::StructVariantState,
        key: &'static str,
        value: V,
    ) -> Result<(), Self::Error>
       where V: Serialize;
    fn serialize_struct_variant_end(
        &mut self,
        state: Self::StructVariantState,
    ) -> Result<(), Self::Error>;
}

A trait that describes a type that can serialize a stream of values into the underlying format.

For Serialize Developers

Non-aggrergate types like integers and strings can be serialized directly by calling the appropriate function. For Aggregate types there’s an initial serialize_T method that yields a State object that you should not interact with. For each part of the aggregate there’s a serialize_T_elt method that allows you to pass values or key/value pairs. The types of the values or the keys may change between calls, but the serialization format may not necessarily accept it. The serialize_T_elt method also takes a mutable reference to the state object. Make sure that you always use the same state object and only the state object that was returned by the serialize_T method. Finally, when your object is done, call the serialize_T_end method and pass the state object by value

For Serialization Format Developers

If your format has different situations where it accepts different types, create a Serializer for each situation. You can create the sub-Serializer in one of the aggregate serialize_T methods and return it as a state object. Remember to also set the corresponding associated type TState. In the serialize_T_elt methods you will be given a mutable reference to that state. You do not need to do any additional checks for the correctness of the state object, as it is expected that the user will not modify it. Due to the generic nature of the Serialize impls, modifying the object is impossible on stable Rust.

Required Associated Types

type Error: Error

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

type SeqState

A state object that is initialized by serialize_seq, passed to serialize_seq_elt, and consumed by serialize_seq_end. Use () if no state is required.

type TupleState

A state object that is initialized by serialize_tuple, passed to serialize_tuple_elt, and consumed by serialize_tuple_end. Use () if no state is required.

type TupleStructState

A state object that is initialized by serialize_tuple_struct, passed to serialize_tuple_struct_elt, and consumed by serialize_tuple_struct_end. Use () if no state is required.

type TupleVariantState

A state object that is initialized by serialize_tuple_variant, passed to serialize_tuple_variant_elt, and consumed by serialize_tuple_variant_end. Use () if no state is required.

type MapState

A state object that is initialized by serialize_map, passed to serialize_map_elt, and consumed by serialize_map_end. Use () if no state is required.

type StructState

A state object that is initialized by serialize_struct, passed to serialize_struct_elt, and consumed by serialize_struct_end. Use () if no state is required.

type StructVariantState

A state object that is initialized by serialize_struct_variant, passed to serialize_struct_variant_elt, and consumed by serialize_struct_variant_end. Use () if no state is required.

Required Methods

fn serialize_bool(&mut self, v: bool) -> Result<(), Self::Error>

Serializes a bool value.

fn serialize_isize(&mut self, v: isize) -> Result<(), Self::Error>

Serializes an isize value. If the format does not differentiate between isize and i64, a reasonable implementation would be to cast the value to i64 and forward to serialize_i64.

fn serialize_i8(&mut self, v: i8) -> Result<(), Self::Error>

Serializes an i8 value. If the format does not differentiate between i8 and i64, a reasonable implementation would be to cast the value to i64 and forward to serialize_i64.

fn serialize_i16(&mut self, v: i16) -> Result<(), Self::Error>

Serializes an i16 value. If the format does not differentiate between i16 and i64, a reasonable implementation would be to cast the value to i64 and forward to serialize_i64.

fn serialize_i32(&mut self, v: i32) -> Result<(), Self::Error>

Serializes an i32 value. If the format does not differentiate between i32 and i64, a reasonable implementation would be to cast the value to i64 and forward to serialize_i64.

fn serialize_i64(&mut self, v: i64) -> Result<(), Self::Error>

Serializes an i64 value.

fn serialize_usize(&mut self, v: usize) -> Result<(), Self::Error>

Serializes a usize value. If the format does not differentiate between usize and u64, a reasonable implementation would be to cast the value to u64 and forward to serialize_u64.

fn serialize_u8(&mut self, v: u8) -> Result<(), Self::Error>

Serializes a u8 value. If the format does not differentiate between u8 and u64, a reasonable implementation would be to cast the value to u64 and forward to serialize_u64.

fn serialize_u16(&mut self, v: u16) -> Result<(), Self::Error>

Serializes a u16 value. If the format does not differentiate between u16 and u64, a reasonable implementation would be to cast the value to u64 and forward to serialize_u64.

fn serialize_u32(&mut self, v: u32) -> Result<(), Self::Error>

Serializes a u32 value. If the format does not differentiate between u32 and u64, a reasonable implementation would be to cast the value to u64 and forward to serialize_u64.

fn serialize_u64(&mut self, v: u64) -> Result<(), Self::Error>

Serializes a u64` value.

fn serialize_f32(&mut self, v: f32) -> Result<(), Self::Error>

Serializes an f32 value. If the format does not differentiate between f32 and f64, a reasonable implementation would be to cast the value to f64 and forward to serialize_f64.

fn serialize_f64(&mut self, v: f64) -> Result<(), Self::Error>

Serializes an f64 value.

fn serialize_char(&mut self, v: char) -> Result<(), Self::Error>

Serializes a character. If the format does not support characters, it is reasonable to serialize it as a single element str or a u32.

fn serialize_str(&mut self, value: &str) -> Result<(), Self::Error>

Serializes a &str.

fn serialize_bytes(&mut self, value: &[u8]) -> Result<(), Self::Error>

Enables serializers to serialize byte slices more compactly or more efficiently than other types of slices. If no efficient implementation is available, a reasonable implementation would be to forward to serialize_seq. If forwarded, the implementation looks usually just like this:

let mut state = try!(self.serialize_seq(value));
for b in value {
    try!(self.serialize_seq_elt(&mut state, b));
}
self.serialize_seq_end(state)

fn serialize_unit(&mut self) -> Result<(), Self::Error>

Serializes a () value. It’s reasonable to just not serialize anything.

fn serialize_unit_struct( &mut self, name: &'static str, ) -> Result<(), Self::Error>

Serializes a unit struct value. A reasonable implementation would be to forward to serialize_unit.

fn serialize_unit_variant( &mut self, name: &'static str, variant_index: usize, variant: &'static str, ) -> Result<(), Self::Error>

Serializes a unit variant, otherwise known as a variant with no arguments. A reasonable implementation would be to forward to serialize_unit.

fn serialize_newtype_struct<T>( &mut self, name: &'static str, value: T, ) -> Result<(), Self::Error>

where T: Serialize,

Allows a tuple struct with a single element, also known as a newtype struct, to be more efficiently serialized than a tuple struct with multiple items. A reasonable implementation would be to forward to serialize_tuple_struct or to just serialize the inner value without wrapping.

fn serialize_newtype_variant<T>( &mut self, name: &'static str, variant_index: usize, variant: &'static str, value: T, ) -> Result<(), Self::Error>

where T: Serialize,

Allows a variant with a single item to be more efficiently serialized than a variant with multiple items. A reasonable implementation would be to forward to serialize_tuple_variant.

fn serialize_none(&mut self) -> Result<(), Self::Error>

Serializes a None value.

fn serialize_some<T>(&mut self, value: T) -> Result<(), Self::Error>

where T: Serialize,

Serializes a Some(...) value.

fn serialize_seq( &mut self, len: Option<usize>, ) -> Result<Self::SeqState, Self::Error>

Begins to serialize a sequence. This call must be followed by zero or more calls to serialize_seq_elt, then a call to serialize_seq_end.

fn serialize_seq_elt<T>( &mut self, state: &mut Self::SeqState, value: T, ) -> Result<(), Self::Error>

where T: Serialize,

Serializes a sequence element. Must have previously called serialize_seq.

fn serialize_seq_end( &mut self, state: Self::SeqState, ) -> Result<(), Self::Error>

Finishes serializing a sequence.

fn serialize_seq_fixed_size( &mut self, size: usize, ) -> Result<Self::SeqState, Self::Error>

Begins to serialize a sequence whose length will be known at deserialization time. This call must be followed by zero or more calls to serialize_seq_elt, then a call to serialize_seq_end. A reasonable implementation would be to forward to serialize_seq.

fn serialize_tuple( &mut self, len: usize, ) -> Result<Self::TupleState, Self::Error>

Begins to serialize a tuple. This call must be followed by zero or more calls to serialize_tuple_elt, then a call to serialize_tuple_end. A reasonable implementation would be to forward to serialize_seq.

fn serialize_tuple_elt<T>( &mut self, state: &mut Self::TupleState, value: T, ) -> Result<(), Self::Error>

where T: Serialize,

Serializes a tuple element. Must have previously called serialize_tuple.

fn serialize_tuple_end( &mut self, state: Self::TupleState, ) -> Result<(), Self::Error>

Finishes serializing a tuple.

fn serialize_tuple_struct( &mut self, name: &'static str, len: usize, ) -> Result<Self::TupleStructState, Self::Error>

Begins to serialize a tuple struct. This call must be followed by zero or more calls to serialize_tuple_struct_elt, then a call to serialize_tuple_struct_end. A reasonable implementation would be to forward to serialize_tuple.

fn serialize_tuple_struct_elt<T>( &mut self, state: &mut Self::TupleStructState, value: T, ) -> Result<(), Self::Error>

where T: Serialize,

Serializes a tuple struct element. Must have previously called serialize_tuple_struct.

fn serialize_tuple_struct_end( &mut self, state: Self::TupleStructState, ) -> Result<(), Self::Error>

Finishes serializing a tuple struct.

fn serialize_tuple_variant( &mut self, name: &'static str, variant_index: usize, variant: &'static str, len: usize, ) -> Result<Self::TupleVariantState, Self::Error>

Begins to serialize a tuple variant. This call must be followed by zero or more calls to serialize_tuple_variant_elt, then a call to serialize_tuple_variant_end. A reasonable implementation would be to forward to serialize_tuple_struct.

fn serialize_tuple_variant_elt<T>( &mut self, state: &mut Self::TupleVariantState, value: T, ) -> Result<(), Self::Error>

where T: Serialize,

Serializes a tuple variant element. Must have previously called serialize_tuple_variant.

fn serialize_tuple_variant_end( &mut self, state: Self::TupleVariantState, ) -> Result<(), Self::Error>

Finishes serializing a tuple variant.

fn serialize_map( &mut self, len: Option<usize>, ) -> Result<Self::MapState, Self::Error>

Begins to serialize a map. This call must be followed by zero or more calls to serialize_map_key and serialize_map_value, then a call to serialize_map_end.

fn serialize_map_key<T>( &mut self, state: &mut Self::MapState, key: T, ) -> Result<(), Self::Error>

where T: Serialize,

Serialize a map key. Must have previously called serialize_map.

fn serialize_map_value<T>( &mut self, state: &mut Self::MapState, value: T, ) -> Result<(), Self::Error>

where T: Serialize,

Serialize a map value. Must have previously called serialize_map.

fn serialize_map_end( &mut self, state: Self::MapState, ) -> Result<(), Self::Error>

Finishes serializing a map.

fn serialize_struct( &mut self, name: &'static str, len: usize, ) -> Result<Self::StructState, Self::Error>

Begins to serialize a struct. This call must be followed by zero or more calls to serialize_struct_elt, then a call to serialize_struct_end.

fn serialize_struct_elt<V>( &mut self, state: &mut Self::StructState, key: &'static str, value: V, ) -> Result<(), Self::Error>

where V: Serialize,

Serializes a struct field. Must have previously called serialize_struct.

fn serialize_struct_end( &mut self, state: Self::StructState, ) -> Result<(), Self::Error>

Finishes serializing a struct.

fn serialize_struct_variant( &mut self, name: &'static str, variant_index: usize, variant: &'static str, len: usize, ) -> Result<Self::StructVariantState, Self::Error>

Begins to serialize a struct variant. This call must be followed by zero or more calls to serialize_struct_variant_elt, then a call to serialize_struct_variant_end.

fn serialize_struct_variant_elt<V>( &mut self, state: &mut Self::StructVariantState, key: &'static str, value: V, ) -> Result<(), Self::Error>

where V: Serialize,

Serialize a struct variant element. Must have previously called serialize_struct_variant.

fn serialize_struct_variant_end( &mut self, state: Self::StructVariantState, ) -> Result<(), Self::Error>

Finishes serializing a struct variant.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors