Enum MaybeUndefined 

pub enum MaybeUndefined<T> {
    Undefined,
    Null,
    Value(T),
}

Similar to Option, but it has three states, undefined, null and x.

When using with Serde, you will likely want to skip serialization of undefined and add a default for deserialization.

Example

use agent_client_protocol_schema::MaybeUndefined;
use serde::{Serialize, Deserialize};

#[derive(Serialize, Deserialize, Eq, PartialEq, Debug)]
struct A {
    #[serde(default, skip_serializing_if = "MaybeUndefined::is_undefined")]
    a: MaybeUndefined<i32>,
}

Variants

Undefined

Null

Value(T)

Implementations

impl<T> MaybeUndefined<T>

pub const fn is_undefined(&self) -> bool

Returns true if the MaybeUndefined<T> is undefined.

pub const fn is_null(&self) -> bool

Returns true if the MaybeUndefined<T> is null.

pub const fn is_value(&self) -> bool

Returns true if the MaybeUndefined<T> contains value.

pub const fn value(&self) -> Option<&T>

Borrow the value, returns None if the the MaybeUndefined<T> is undefined or null, otherwise returns Some(T).

pub fn take(self) -> Option<T>

Converts the MaybeUndefined<T> to Option<T>.

pub const fn as_opt_ref(&self) -> Option<Option<&T>>

Converts the MaybeUndefined<T> to Option<Option<T>>.

pub fn as_opt_deref<U>(&self) -> Option<Option<&U>>

where T: Deref<Target = U>, U: ?Sized,

Converts the MaybeUndefined<T> to Option<Option<&U>>.

pub fn contains_value<U>(&self, x: &U) -> bool

where U: PartialEq<T>,

Returns true if the MaybeUndefined<T> contains the given value.

pub fn contains<U>(&self, x: Option<&U>) -> bool

where U: PartialEq<T>,

Returns true if the MaybeUndefined<T> contains the given nullable value.

pub fn map<U, F>(self, f: F) -> MaybeUndefined<U>

where F: FnOnce(Option<T>) -> Option<U>,

Maps a MaybeUndefined<T> to MaybeUndefined<U> by applying a function to the contained nullable value

pub fn map_value<U, F>(self, f: F) -> MaybeUndefined<U>

where F: FnOnce(T) -> U,

Maps a MaybeUndefined<T> to MaybeUndefined<U> by applying a function to the contained value

pub fn update_to(self, value: &mut Option<T>)

Update value if the MaybeUndefined<T> is not undefined.

Example

use agent_client_protocol_schema::MaybeUndefined;

let mut value = None;

MaybeUndefined::Value(10i32).update_to(&mut value);
assert_eq!(value, Some(10));

MaybeUndefined::Undefined.update_to(&mut value);
assert_eq!(value, Some(10));

MaybeUndefined::Null.update_to(&mut value);
assert_eq!(value, None);

impl<T, E> MaybeUndefined<Result<T, E>>

pub fn transpose(self) -> Result<MaybeUndefined<T>, E>

Transposes a MaybeUndefined of a Result into a Result of a MaybeUndefined.

MaybeUndefined::Undefined will be mapped to Ok(MaybeUndefined::Undefined). MaybeUndefined::Null will be mapped to Ok(MaybeUndefined::Null). MaybeUndefined::Value(Ok(_)) and MaybeUndefined::Value(Err(_)) will be mapped to Ok(MaybeUndefined::Value(_)) and Err(_).

Errors

Returns an error if the input is MaybeUndefined::Value(Err(_)).

Trait Implementations

impl<T> Clone for MaybeUndefined<T>

where T: Clone,

fn clone(&self) -> MaybeUndefined<T>

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T> Debug for MaybeUndefined<T>

where T: Debug,

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl<T> Default for MaybeUndefined<T>

fn default() -> MaybeUndefined<T>

Returns the “default value” for a type.

impl<'de, T> Deserialize<'de> for MaybeUndefined<T>

where T: Deserialize<'de>,

fn deserialize<D>( deserializer: D, ) -> Result<MaybeUndefined<T>, <D as Deserializer<'de>>::Error>

where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl<T> From<Option<Option<T>>> for MaybeUndefined<T>

fn from(value: Option<Option<T>>) -> MaybeUndefined<T>

Converts to this type from the input type.

impl<T> Hash for MaybeUndefined<T>

where T: Hash,

fn hash<__H>(&self, state: &mut __H)

where __H: Hasher,

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl<T> IntoMaybeUndefined<T> for MaybeUndefined<T>

fn into_maybe_undefined(self) -> MaybeUndefined<T>

impl<T> JsonSchema for MaybeUndefined<T>

where T: JsonSchema,

fn schema_name() -> Cow<'static, str>

The name of the generated JSON Schema.

fn schema_id() -> Cow<'static, str>

Returns a string that uniquely identifies the schema produced by this type.

fn json_schema(generator: &mut SchemaGenerator) -> Schema

Generates a JSON Schema for this type.

fn inline_schema() -> bool

Whether JSON Schemas generated for this type should be included directly in parent schemas, rather than being re-used where possible using the $ref keyword.

impl<T> Ord for MaybeUndefined<T>

where T: Ord,

fn cmp(&self, other: &MaybeUndefined<T>) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl<T> PartialEq for MaybeUndefined<T>

where T: PartialEq,

fn eq(&self, other: &MaybeUndefined<T>) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<T> PartialOrd for MaybeUndefined<T>

where T: PartialOrd,

fn partial_cmp(&self, other: &MaybeUndefined<T>) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl<T> Serialize for MaybeUndefined<T>

where T: Serialize,

fn serialize<S>( &self, serializer: S, ) -> Result<<S as Serializer>::Ok, <S as Serializer>::Error>

where S: Serializer,

Serialize this value into the given Serde serializer.

impl<T> Copy for MaybeUndefined<T>

where T: Copy,

impl<T> Eq for MaybeUndefined<T>

where T: Eq,

impl<T> StructuralPartialEq for MaybeUndefined<T>