Enum PatchValue 

pub enum PatchValue<T> {
    Unchanged,
    Set(T),
    Clear,
}

One field’s requested change.

Variants

Unchanged

The user did not name this field. Never mutates it.

Set(T)

Set to this value.

Clear

Empty the field, where the field supports clearing.

Implementations

impl<T> PatchValue<T>

pub fn is_unchanged(&self) -> bool

Whether this value would change anything. The cheap form of the “already the requested state is a no-op” rule (data-model §2): a plan can skip the field without comparing it to the current value.

pub fn is_clear(&self) -> bool

pub fn as_set(&self) -> Option<&T>

The value, or None for both Unchanged and Clear.

pub fn map<U, F: FnOnce(T) -> U>(self, f: F) -> PatchValue<U>

Map the payload, leaving the variant alone.

Trait Implementations

impl<T: Clone> Clone for PatchValue<T>

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<T: Copy> Copy for PatchValue<T>

impl<T: Debug> Debug for PatchValue<T>

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

Formats the value using the given formatter.

impl<T> Default for PatchValue<T>

fn default() -> Self

Returns the “default value” for a type.

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

where T: Deserialize<'de>,

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl<T: Eq> Eq for PatchValue<T>

impl<T> From<Option<T>> for PatchValue<T>

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

None becomes Unchanged, not Clear.

This conversion is the one place the distinction could be lost, so it is deliberately one-way: Option cannot express Clear on its own, and a caller that means to clear has to write PatchValue::Clear by hand.

impl<T: PartialEq> PartialEq for PatchValue<T>

fn eq(&self, other: &Self) -> bool

Equality operator ==.

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

Inequality operator !=.

impl<T> Serialize for PatchValue<T>

where T: Serialize,

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl<T: PartialEq> StructuralPartialEq for PatchValue<T>