Struct p256::AffinePoint

source · [−]

pub struct AffinePoint { /* private fields */ }

This is supported on crate feature arithmetic only.

Expand description

NIST P-256 (secp256r1) curve point expressed in affine coordinates.

`serde` support

When the serde feature of this crate is enabled, the Serialize and Deserialize traits are impl’d for this type.

The serialization uses the SEC1 Elliptic-Curve-Point-to-Octet-String encoding, serialized as binary.

When serialized with a text-based format, the SEC1 representation is subsequently hex encoded.

Implementations

source

impl AffinePoint

source

pub const IDENTITY: Self

Additive identity of the group: the point at infinity.

source

pub const GENERATOR: Self

Base point of P-256.

Defined in FIPS 186-4 § D.1.2.3:

Gₓ = 6b17d1f2 e12c4247 f8bce6e5 63a440f2 77037d81 2deb33a0 f4a13945 d898c296
Gᵧ = 4fe342e2 fe1a7f9b 8ee7eb4a 7c0f9e16 2bce3357 6b315ece cbb64068 37bf51f5

Trait Implementations

source

impl Add<&'_ AffinePoint> for &ProjectivePoint

type Output = ProjectivePoint

The resulting type after applying the + operator.

source

fn add(self, other: &AffinePoint) -> ProjectivePoint

Performs the + operation. Read more

source

impl Add<&'_ AffinePoint> for ProjectivePoint

type Output = ProjectivePoint

The resulting type after applying the + operator.

source

fn add(self, other: &AffinePoint) -> ProjectivePoint

Performs the + operation. Read more

source

impl Add<AffinePoint> for ProjectivePoint

type Output = ProjectivePoint

The resulting type after applying the + operator.

source

fn add(self, other: AffinePoint) -> ProjectivePoint

Performs the + operation. Read more

source

impl AddAssign<&'_ AffinePoint> for ProjectivePoint

source

fn add_assign(&mut self, rhs: &AffinePoint)

Performs the += operation. Read more

source

impl AddAssign<AffinePoint> for ProjectivePoint

source

fn add_assign(&mut self, rhs: AffinePoint)

Performs the += operation. Read more

source

impl AffineXCoordinate<NistP256> for AffinePoint

source

fn x(&self) -> FieldBytes

Get the affine x-coordinate as a serialized field element.

source

impl Clone for AffinePoint

source

fn clone(&self) -> AffinePoint

Returns a copy of the value. Read more

1.0.0 · source

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

Performs copy-assignment from source. Read more

source

impl ConditionallySelectable for AffinePoint

source

fn conditional_select(
    a: &AffinePoint,
    b: &AffinePoint,
    choice: Choice
) -> AffinePoint

Select a or b according to choice. Read more

source

fn conditional_assign(&mut self, other: &Self, choice: Choice)

Conditionally assign other to self, according to choice. Read more

source

fn conditional_swap(a: &mut Self, b: &mut Self, choice: Choice)

Conditionally swap self and other if choice == 1; otherwise, reassign both unto themselves. Read more

source

impl ConstantTimeEq for AffinePoint

source

fn ct_eq(&self, other: &AffinePoint) -> Choice

Determine if two items are equal. Read more

source

impl Debug for AffinePoint

source

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

Formats the value using the given formatter. Read more

source

impl DecompactPoint<NistP256> for AffinePoint

source

fn decompact(x_bytes: &FieldBytes) -> CtOption<Self>

Attempt to decompact an elliptic curve point

source

impl DecompressPoint<NistP256> for AffinePoint

source

fn decompress(x_bytes: &FieldBytes, y_is_odd: Choice) -> CtOption<Self>

Attempt to decompress an elliptic curve point.

source

impl Default for AffinePoint

source

fn default() -> Self

Returns the “default value” for a type. Read more

source

impl<'de> Deserialize<'de> for AffinePoint

This is supported on crate feature serde only.

source

fn deserialize<D>(deserializer: D) -> Result<Self, D::Error> where
D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer. Read more

source

impl From<&'_ AffinePoint> for ProjectivePoint

source

fn from(p: &AffinePoint) -> Self

Performs the conversion.

source

impl From<&'_ AffinePoint> for SharedSecret

This is supported on crate feature ecdh only.

source

fn from(affine: &AffinePoint) -> SharedSecret

Performs the conversion.

source

impl From<&'_ ProjectivePoint> for AffinePoint

source

fn from(p: &ProjectivePoint) -> AffinePoint

Performs the conversion.

source

impl From<AffinePoint> for EncodedPoint

source

fn from(affine_point: AffinePoint) -> EncodedPoint

Returns the SEC1 compressed encoding of this point.

source

impl From<AffinePoint> for ProjectivePoint

source

fn from(p: AffinePoint) -> Self

Performs the conversion.

source

impl From<ProjectivePoint> for AffinePoint

source

fn from(p: ProjectivePoint) -> AffinePoint

Performs the conversion.

source

impl FromEncodedPoint<NistP256> for AffinePoint

source

fn from_encoded_point(encoded_point: &EncodedPoint) -> CtOption<Self>

Attempts to parse the given EncodedPoint as an SEC1-encoded AffinePoint.

Returns

None value if encoded_point is not on the secp256r1 curve.

source

impl GroupEncoding for AffinePoint

source

fn from_bytes(bytes: &Self::Repr) -> CtOption<Self>

NOTE: not constant-time with respect to identity point

type Repr = CompressedPoint

The encoding of group elements. Read more

source

fn from_bytes_unchecked(bytes: &Self::Repr) -> CtOption<Self>

Attempts to deserialize a group element, not checking if the element is valid. Read more

source

fn to_bytes(&self) -> Self::Repr

Converts this element into its byte encoding. This may or may not support encoding the identity. Read more

source

impl Mul<&'_ Scalar> for AffinePoint

type Output = ProjectivePoint

The resulting type after applying the * operator.

source

fn mul(self, scalar: &Scalar) -> ProjectivePoint

Performs the * operation. Read more

source

impl Mul<Scalar> for AffinePoint

type Output = ProjectivePoint

The resulting type after applying the * operator.

source

fn mul(self, scalar: Scalar) -> ProjectivePoint

Performs the * operation. Read more

source

impl Neg for AffinePoint

type Output = AffinePoint

The resulting type after applying the - operator.

source

fn neg(self) -> Self::Output

Performs the unary - operation. Read more

source

impl PartialEq<AffinePoint> for AffinePoint

source

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

This method tests for self and other values to be equal, and is used by ==. Read more

1.0.0 · source

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

This method tests for !=.

source

impl PrimeCurveAffine for AffinePoint

type Scalar = Scalar

type Curve = ProjectivePoint

source

fn identity() -> AffinePoint

Returns the additive identity.

source

fn generator() -> AffinePoint

Returns a fixed generator of unknown exponent.

source

fn is_identity(&self) -> Choice

Determines if this point represents the point at infinity; the additive identity. Read more

source

fn to_curve(&self) -> ProjectivePoint

Converts this element to its curve representation.

source

impl Serialize for AffinePoint

This is supported on crate feature serde only.

source

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

Serialize this value into the given Serde serializer. Read more

source

impl Sub<&'_ AffinePoint> for &ProjectivePoint

type Output = ProjectivePoint

The resulting type after applying the - operator.

source

fn sub(self, other: &AffinePoint) -> ProjectivePoint

Performs the - operation. Read more

source

impl Sub<&'_ AffinePoint> for ProjectivePoint

type Output = ProjectivePoint

The resulting type after applying the - operator.

source

fn sub(self, other: &AffinePoint) -> ProjectivePoint

Performs the - operation. Read more

source

impl Sub<AffinePoint> for ProjectivePoint

type Output = ProjectivePoint

The resulting type after applying the - operator.

source

fn sub(self, other: AffinePoint) -> ProjectivePoint

Performs the - operation. Read more

source

impl SubAssign<&'_ AffinePoint> for ProjectivePoint

source

fn sub_assign(&mut self, rhs: &AffinePoint)

Performs the -= operation. Read more

source

impl SubAssign<AffinePoint> for ProjectivePoint

source

fn sub_assign(&mut self, rhs: AffinePoint)

Performs the -= operation. Read more

source

impl ToCompactEncodedPoint<NistP256> for AffinePoint

source

fn to_compact_encoded_point(&self) -> Option<EncodedPoint>

Serialize this value as a SEC1 compact EncodedPoint

source

impl ToEncodedPoint<NistP256> for AffinePoint

source

fn to_encoded_point(&self, compress: bool) -> EncodedPoint

Serialize this value as a SEC1 EncodedPoint, optionally applying point compression. Read more

source

impl TryFrom<&'_ EncodedPoint<<<NistP256 as Curve>::UInt as ArrayEncoding>::ByteSize>> for AffinePoint

type Error = Error

The type returned in the event of a conversion error.

source

fn try_from(point: &EncodedPoint) -> Result<AffinePoint>

Performs the conversion.

source

impl TryFrom<EncodedPoint<<<NistP256 as Curve>::UInt as ArrayEncoding>::ByteSize>> for AffinePoint

type Error = Error

The type returned in the event of a conversion error.

source

fn try_from(point: EncodedPoint) -> Result<AffinePoint>

Performs the conversion.

source

impl VerifyPrimitive<NistP256> for AffinePoint

This is supported on crate feature ecdsa-core only.

source

fn verify_prehashed(
 &self,
 z: <C as ScalarArithmetic>::Scalar,
 sig: &Signature<C>
) -> Result<(), Error>

Verify the prehashed message against the provided signature Read more

source

impl Copy for AffinePoint

source

impl DefaultIsZeroes for AffinePoint

source

impl Eq for AffinePoint

Auto Trait Implementations

impl RefUnwindSafe for AffinePoint

impl Send for AffinePoint

impl Sync for AffinePoint

impl Unpin for AffinePoint

impl UnwindSafe for AffinePoint

Blanket Implementations

source

impl<T> Any for T where
T: 'static + ?Sized,

source

pub fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more

source

impl<T> Borrow<T> for T where
T: ?Sized,

source

pub fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more

source

impl<T> BorrowMut<T> for T where
T: ?Sized,

source

pub fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more

impl<T> Conv for T

fn conv<T>(self) -> T where
Self: Into<T>,

Converts self into T using Into<T>. Read more

impl<T> FmtForward for T

fn fmt_binary(self) -> FmtBinary<Self> where
Self: Binary,

Causes self to use its Binary implementation when Debug-formatted.

fn fmt_display(self) -> FmtDisplay<Self> where
Self: Display,

Causes self to use its Display implementation when Debug-formatted. Read more

fn fmt_lower_exp(self) -> FmtLowerExp<Self> where
Self: LowerExp,

Causes self to use its LowerExp implementation when Debug-formatted. Read more

fn fmt_lower_hex(self) -> FmtLowerHex<Self> where
Self: LowerHex,

Causes self to use its LowerHex implementation when Debug-formatted. Read more

fn fmt_octal(self) -> FmtOctal<Self> where
Self: Octal,

Causes self to use its Octal implementation when Debug-formatted.

fn fmt_pointer(self) -> FmtPointer<Self> where
Self: Pointer,

Causes self to use its Pointer implementation when Debug-formatted. Read more

fn fmt_upper_exp(self) -> FmtUpperExp<Self> where
Self: UpperExp,

Causes self to use its UpperExp implementation when Debug-formatted. Read more

fn fmt_upper_hex(self) -> FmtUpperHex<Self> where
Self: UpperHex,

Causes self to use its UpperHex implementation when Debug-formatted. Read more

source

impl<T> From<T> for T

source

pub fn from(t: T) -> T

Performs the conversion.

source

impl<T, U> Into for T where
U: From<T>,

source

pub fn into(self) -> U

Performs the conversion.

impl<T> Pipe for T where
T: ?Sized,

fn pipe<R>(self, func: impl FnOnce(Self) -> R) -> R

Pipes by value. This is generally the method you want to use. Read more

fn pipe_ref<'a, R>(&'a self, func: impl FnOnce(&'a Self) -> R) -> R where
R: 'a,

Borrows self and passes that borrow into the pipe function. Read more

fn pipe_ref_mut<'a, R>(&'a mut self, func: impl FnOnce(&'a mut Self) -> R) -> R where
R: 'a,

Mutably borrows self and passes that borrow into the pipe function. Read more

fn pipe_borrow<'a, B, R>(&'a self, func: impl FnOnce(&'a B) -> R) -> R where
 Self: Borrow,
 B: 'a + ?Sized,
 R: 'a,

Borrows self, then passes self.borrow() into the pipe function. Read more

fn pipe_borrow_mut<'a, B, R>(
 &'a mut self,
 func: impl FnOnce(&'a mut B) -> R
) -> R where
 Self: BorrowMut,
 B: 'a + ?Sized,
 R: 'a,

Mutably borrows self, then passes self.borrow_mut() into the pipe function. Read more

fn pipe_as_ref<'a, U, R>(&'a self, func: impl FnOnce(&'a U) -> R) -> R where
 Self: AsRef,
 U: 'a + ?Sized,
 R: 'a,

Borrows self, then passes self.as_ref() into the pipe function.

fn pipe_as_mut<'a, U, R>(&'a mut self, func: impl FnOnce(&'a mut U) -> R) -> R where
 Self: AsMut,
 U: 'a + ?Sized,
 R: 'a,

Mutably borrows self, then passes self.as_mut() into the pipe function. Read more

fn pipe_deref<'a, T, R>(&'a self, func: impl FnOnce(&'a T) -> R) -> R where
 Self: Deref<Target = T>,
 T: 'a + ?Sized,
 R: 'a,

Borrows self, then passes self.deref() into the pipe function.

fn pipe_deref_mut<'a, T, R>(
 &'a mut self,
 func: impl FnOnce(&'a mut T) -> R
) -> R where
 Self: DerefMut<Target = T> + Deref,
 T: 'a + ?Sized,
 R: 'a,

Mutably borrows self, then passes self.deref_mut() into the pipe function. Read more

source

impl<T> Same<T> for T

type Output = T

Should always be Self

impl<T> Tap for T

fn tap(self, func: impl FnOnce(&Self)) -> Self

Immutable access to a value. Read more

fn tap_mut(self, func: impl FnOnce(&mut Self)) -> Self

Mutable access to a value. Read more

fn tap_borrow(self, func: impl FnOnce(&B)) -> Self where
Self: Borrow,
B: ?Sized,

Immutable access to the Borrow of a value. Read more

fn tap_borrow_mut(self, func: impl FnOnce(&mut B)) -> Self where
Self: BorrowMut,
B: ?Sized,

Mutable access to the BorrowMut of a value. Read more

fn tap_ref<R>(self, func: impl FnOnce(&R)) -> Self where
Self: AsRef<R>,
R: ?Sized,

Immutable access to the AsRef<R> view of a value. Read more

fn tap_ref_mut<R>(self, func: impl FnOnce(&mut R)) -> Self where
Self: AsMut<R>,
R: ?Sized,

Mutable access to the AsMut<R> view of a value. Read more

fn tap_deref<T>(self, func: impl FnOnce(&T)) -> Self where
Self: Deref<Target = T>,
T: ?Sized,

Immutable access to the Deref::Target of a value. Read more

fn tap_deref_mut<T>(self, func: impl FnOnce(&mut T)) -> Self where
Self: DerefMut<Target = T> + Deref,
T: ?Sized,

Mutable access to the Deref::Target of a value. Read more

fn tap_dbg(self, func: impl FnOnce(&Self)) -> Self

Calls .tap() only in debug builds, and is erased in release builds.

fn tap_mut_dbg(self, func: impl FnOnce(&mut Self)) -> Self

Calls .tap_mut() only in debug builds, and is erased in release builds. Read more

fn tap_borrow_dbg(self, func: impl FnOnce(&B)) -> Self where
Self: Borrow,
B: ?Sized,

Calls .tap_borrow() only in debug builds, and is erased in release builds. Read more

fn tap_borrow_mut_dbg(self, func: impl FnOnce(&mut B)) -> Self where
Self: BorrowMut,
B: ?Sized,

Calls .tap_borrow_mut() only in debug builds, and is erased in release builds. Read more

fn tap_ref_dbg<R>(self, func: impl FnOnce(&R)) -> Self where
Self: AsRef<R>,
R: ?Sized,

Calls .tap_ref() only in debug builds, and is erased in release builds. Read more

fn tap_ref_mut_dbg<R>(self, func: impl FnOnce(&mut R)) -> Self where
Self: AsMut<R>,
R: ?Sized,

Calls .tap_ref_mut() only in debug builds, and is erased in release builds. Read more

fn tap_deref_dbg<T>(self, func: impl FnOnce(&T)) -> Self where
Self: Deref<Target = T>,
T: ?Sized,

Calls .tap_deref() only in debug builds, and is erased in release builds. Read more

fn tap_deref_mut_dbg<T>(self, func: impl FnOnce(&mut T)) -> Self where
Self: DerefMut<Target = T> + Deref,
T: ?Sized,

Calls .tap_deref_mut() only in debug builds, and is erased in release builds. Read more

source

impl<T> ToOwned for T where
T: Clone,

type Owned = T

The resulting type after obtaining ownership.

source

pub fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more

source

pub fn clone_into(&self, target: &mut T)

🔬 This is a nightly-only experimental API. (toowned_clone_into)

Uses borrowed data to replace owned data, usually by cloning. Read more

impl<T> TryConv for T

fn try_conv<T>(self) -> Result<T, Self::Error> where
Self: TryInto<T>,

Attempts to convert self into T using TryInto<T>. Read more

source

impl<T, U> TryFrom for T where
U: Into<T>,

type Error = Infallible

The type returned in the event of a conversion error.

source

pub fn try_from(value: U) -> Result<T, <T as TryFrom>::Error>

Performs the conversion.

source

impl<T, U> TryInto for T where
U: TryFrom<T>,

type Error = >::Error

The type returned in the event of a conversion error.

source

pub fn try_into(self) -> Result<U, >::Error>

Performs the conversion.

source

impl<Z> Zeroize for Z where
Z: DefaultIsZeroes,

source

pub fn zeroize(&mut self)

Zero out this object from memory using Rust intrinsics which ensure the zeroization operation is not “optimized away” by the compiler. Read more

source

Struct p256::AffinePoint

serde support

Implementations

impl AffinePoint

pub const IDENTITY: Self

pub const GENERATOR: Self

Trait Implementations

impl Add<&'_ AffinePoint> for &ProjectivePoint

type Output = ProjectivePoint

fn add(self, other: &AffinePoint) -> ProjectivePoint

impl Add<&'_ AffinePoint> for ProjectivePoint

type Output = ProjectivePoint

fn add(self, other: &AffinePoint) -> ProjectivePoint

impl Add<AffinePoint> for ProjectivePoint

type Output = ProjectivePoint

fn add(self, other: AffinePoint) -> ProjectivePoint

impl AddAssign<&'_ AffinePoint> for ProjectivePoint

fn add_assign(&mut self, rhs: &AffinePoint)

impl AddAssign<AffinePoint> for ProjectivePoint

fn add_assign(&mut self, rhs: AffinePoint)

impl AffineXCoordinate<NistP256> for AffinePoint

fn x(&self) -> FieldBytes

impl Clone for AffinePoint

fn clone(&self) -> AffinePoint

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

impl ConditionallySelectable for AffinePoint

fn conditional_select( a: &AffinePoint, b: &AffinePoint, choice: Choice) -> AffinePoint

fn conditional_assign(&mut self, other: &Self, choice: Choice)

fn conditional_swap(a: &mut Self, b: &mut Self, choice: Choice)

impl ConstantTimeEq for AffinePoint

fn ct_eq(&self, other: &AffinePoint) -> Choice

impl Debug for AffinePoint

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

impl DecompactPoint<NistP256> for AffinePoint

fn decompact(x_bytes: &FieldBytes) -> CtOption<Self>

impl DecompressPoint<NistP256> for AffinePoint

fn decompress(x_bytes: &FieldBytes, y_is_odd: Choice) -> CtOption<Self>

impl Default for AffinePoint

fn default() -> Self

impl<'de> Deserialize<'de> for AffinePoint

fn deserialize<D>(deserializer: D) -> Result<Self, D::Error> where D: Deserializer<'de>,

impl From<&'_ AffinePoint> for ProjectivePoint

fn from(p: &AffinePoint) -> Self

impl From<&'_ AffinePoint> for SharedSecret

fn from(affine: &AffinePoint) -> SharedSecret

impl From<&'_ ProjectivePoint> for AffinePoint

fn from(p: &ProjectivePoint) -> AffinePoint

impl From<AffinePoint> for EncodedPoint

fn from(affine_point: AffinePoint) -> EncodedPoint

impl From<AffinePoint> for ProjectivePoint

fn from(p: AffinePoint) -> Self

impl From<ProjectivePoint> for AffinePoint

fn from(p: ProjectivePoint) -> AffinePoint

impl FromEncodedPoint<NistP256> for AffinePoint

fn from_encoded_point(encoded_point: &EncodedPoint) -> CtOption<Self>

Returns

impl GroupEncoding for AffinePoint

fn from_bytes(bytes: &Self::Repr) -> CtOption<Self>

type Repr = CompressedPoint

fn from_bytes_unchecked(bytes: &Self::Repr) -> CtOption<Self>

fn to_bytes(&self) -> Self::Repr

impl Mul<&'_ Scalar> for AffinePoint

type Output = ProjectivePoint

fn mul(self, scalar: &Scalar) -> ProjectivePoint

impl Mul<Scalar> for AffinePoint

type Output = ProjectivePoint

fn mul(self, scalar: Scalar) -> ProjectivePoint

impl Neg for AffinePoint

type Output = AffinePoint

fn neg(self) -> Self::Output

impl PartialEq<AffinePoint> for AffinePoint

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

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

impl PrimeCurveAffine for AffinePoint

type Scalar = Scalar

type Curve = ProjectivePoint

fn identity() -> AffinePoint

fn generator() -> AffinePoint

fn is_identity(&self) -> Choice

fn to_curve(&self) -> ProjectivePoint

`serde` support

fn conditional_select(
a: &AffinePoint,
b: &AffinePoint,
choice: Choice
) -> AffinePoint

fn deserialize<D>(deserializer: D) -> Result<Self, D::Error> where
D: Deserializer<'de>,

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

fn verify_prehashed(
&self,
z: <C as ScalarArithmetic>::Scalar,
sig: &Signature<C>
) -> Result<(), Error>

impl<T> Any for T where
T: 'static + ?Sized,

impl<T> Borrow<T> for T where
T: ?Sized,

impl<T> BorrowMut<T> for T where
T: ?Sized,

fn conv<T>(self) -> T where
Self: Into<T>,

fn fmt_binary(self) -> FmtBinary<Self> where
Self: Binary,

fn fmt_display(self) -> FmtDisplay<Self> where
Self: Display,

fn fmt_lower_exp(self) -> FmtLowerExp<Self> where
Self: LowerExp,

fn fmt_lower_hex(self) -> FmtLowerHex<Self> where
Self: LowerHex,

fn fmt_octal(self) -> FmtOctal<Self> where
Self: Octal,

fn fmt_pointer(self) -> FmtPointer<Self> where
Self: Pointer,

fn fmt_upper_exp(self) -> FmtUpperExp<Self> where
Self: UpperExp,

fn fmt_upper_hex(self) -> FmtUpperHex<Self> where
Self: UpperHex,

impl<T, U> Into<U> for T where
U: From<T>,

impl<T> Pipe for T where
T: ?Sized,

fn pipe_ref<'a, R>(&'a self, func: impl FnOnce(&'a Self) -> R) -> R where
R: 'a,

fn pipe_ref_mut<'a, R>(&'a mut self, func: impl FnOnce(&'a mut Self) -> R) -> R where
R: 'a,

fn pipe_borrow<'a, B, R>(&'a self, func: impl FnOnce(&'a B) -> R) -> R where
Self: Borrow<B>,
B: 'a + ?Sized,
R: 'a,

fn pipe_borrow_mut<'a, B, R>(
&'a mut self,
func: impl FnOnce(&'a mut B) -> R
) -> R where
Self: BorrowMut<B>,
B: 'a + ?Sized,
R: 'a,