1.34.0[−][src]Enum nom::lib::std::convert::Infallible
The error type for errors that can never happen.
Since this enum has no variant, a value of this type can never actually exist.
This can be useful for generic APIs that use Result
and parameterize the error type,
to indicate that the result is always Ok
.
For example, the TryFrom
trait (conversion that returns a Result
)
has a blanket implementation for all types where a reverse Into
implementation exists.
impl<T, U> TryFrom<U> for T where U: Into<T> { type Error = Infallible; fn try_from(value: U) -> Result<Self, Infallible> { Ok(U::into(value)) // Never returns `Err` } }
Future compatibility
This enum has the same role as the !
“never” type,
which is unstable in this version of Rust.
When !
is stabilized, we plan to make Infallible
a type alias to it:
pub type Infallible = !;
… and eventually deprecate Infallible
.
However there is one case where !
syntax can be used
before !
is stabilized as a full-fledged type: in the position of a function’s return type.
Specifically, it is possible implementations for two different function pointer types:
trait MyTrait {} impl MyTrait for fn() -> ! {} impl MyTrait for fn() -> std::convert::Infallible {}
With Infallible
being an enum, this code is valid.
However when Infallible
becomes an alias for the never type,
the two impl
s will start to overlap
and therefore will be disallowed by the language’s trait coherence rules.
Trait Implementations
impl Clone for Infallible
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pub fn clone(&self) -> Infallible
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fn clone_from(&mut self, source: &Self)
1.0.0[src]
impl Copy for Infallible
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impl Debug for Infallible
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impl Display for Infallible
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impl Eq for Infallible
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impl Error for Infallible
1.8.0[src]
pub fn description(&self) -> &str
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fn source(&self) -> Option<&(dyn Error + 'static)>
1.30.0[src]
fn backtrace(&self) -> Option<&Backtrace>
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fn cause(&self) -> Option<&dyn Error>
1.0.0[src]
impl From<!> for Infallible
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pub fn from(x: !) -> Infallible
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impl From<Infallible> for TryFromSliceError
1.36.0[src]
pub fn from(x: Infallible) -> TryFromSliceError
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impl From<Infallible> for TryFromIntError
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pub fn from(x: Infallible) -> TryFromIntError
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impl Hash for Infallible
1.44.0[src]
pub fn hash<H>(&self, &mut H) where
H: Hasher,
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H: Hasher,
fn hash_slice<H>(data: &[Self], state: &mut H) where
H: Hasher,
1.3.0[src]
H: Hasher,
impl Ord for Infallible
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pub fn cmp(&self, _other: &Infallible) -> Ordering
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#[must_use]fn max(self, other: Self) -> Self
1.21.0[src]
#[must_use]fn min(self, other: Self) -> Self
1.21.0[src]
#[must_use]fn clamp(self, min: Self, max: Self) -> Self
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impl PartialEq<Infallible> for Infallible
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impl PartialOrd<Infallible> for Infallible
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Auto Trait Implementations
impl RefUnwindSafe for Infallible
impl Send for Infallible
impl Sync for Infallible
impl Unpin for Infallible
impl UnwindSafe for Infallible
Blanket Implementations
impl<T> Any for T where
T: 'static + ?Sized,
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T: 'static + ?Sized,
impl<T> Borrow<T> for T where
T: ?Sized,
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T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
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T: ?Sized,
pub fn borrow_mut(&mut self) -> &mut Tⓘ
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impl<T> Conv for T
impl<T> Conv for T
impl<T> FmtForward for T
fn fmt_binary(self) -> FmtBinary<Self> where
Self: Binary,
Self: Binary,
fn fmt_display(self) -> FmtDisplay<Self> where
Self: Display,
Self: Display,
fn fmt_lower_exp(self) -> FmtLowerExp<Self> where
Self: LowerExp,
Self: LowerExp,
fn fmt_lower_hex(self) -> FmtLowerHex<Self> where
Self: LowerHex,
Self: LowerHex,
fn fmt_octal(self) -> FmtOctal<Self> where
Self: Octal,
Self: Octal,
fn fmt_pointer(self) -> FmtPointer<Self> where
Self: Pointer,
Self: Pointer,
fn fmt_upper_exp(self) -> FmtUpperExp<Self> where
Self: UpperExp,
Self: UpperExp,
fn fmt_upper_hex(self) -> FmtUpperHex<Self> where
Self: UpperHex,
Self: UpperHex,
impl<T> From<!> for T
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impl<T> From<T> for T
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impl<T, U> Into<U> for T where
U: From<T>,
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U: From<T>,
impl<T> Pipe for T where
T: ?Sized,
T: ?Sized,
fn pipe<R>(self, func: impl FnOnce(Self) -> R) -> R
fn pipe_ref<'a, R>(&'a self, func: impl FnOnce(&'a Self) -> R) -> R where
R: 'a,
R: 'a,
fn pipe_ref_mut<'a, R>(&'a mut self, func: impl FnOnce(&'a mut Self) -> R) -> R where
R: 'a,
R: 'a,
fn pipe_borrow<'a, B, R>(&'a self, func: impl FnOnce(&'a B) -> R) -> R where
B: 'a + ?Sized,
R: 'a,
Self: Borrow<B>,
B: 'a + ?Sized,
R: 'a,
Self: Borrow<B>,
fn pipe_borrow_mut<'a, B, R>(
&'a mut self,
func: impl FnOnce(&'a mut B) -> R
) -> R where
B: 'a + ?Sized,
R: 'a,
Self: BorrowMut<B>,
&'a mut self,
func: impl FnOnce(&'a mut B) -> R
) -> R where
B: 'a + ?Sized,
R: 'a,
Self: BorrowMut<B>,
fn pipe_as_ref<'a, U, R>(&'a self, func: impl FnOnce(&'a U) -> R) -> R where
R: 'a,
Self: AsRef<U>,
U: 'a + ?Sized,
R: 'a,
Self: AsRef<U>,
U: 'a + ?Sized,
fn pipe_as_mut<'a, U, R>(&'a mut self, func: impl FnOnce(&'a mut U) -> R) -> R where
R: 'a,
Self: AsMut<U>,
U: 'a + ?Sized,
R: 'a,
Self: AsMut<U>,
U: 'a + ?Sized,
fn pipe_deref<'a, T, R>(&'a self, func: impl FnOnce(&'a T) -> R) -> R where
R: 'a,
Self: Deref<Target = T>,
T: 'a + ?Sized,
R: 'a,
Self: Deref<Target = T>,
T: 'a + ?Sized,
fn pipe_deref_mut<'a, T, R>(
&'a mut self,
func: impl FnOnce(&'a mut T) -> R
) -> R where
R: 'a,
Self: DerefMut<Target = T> + Deref,
T: 'a + ?Sized,
&'a mut self,
func: impl FnOnce(&'a mut T) -> R
) -> R where
R: 'a,
Self: DerefMut<Target = T> + Deref,
T: 'a + ?Sized,
impl<T> Pipe for T
impl<T> PipeAsRef for T
fn pipe_as_ref<'a, T, R>(&'a self, func: impl FnOnce(&'a T) -> R) -> R where
R: 'a,
Self: AsRef<T>,
T: 'a,
R: 'a,
Self: AsRef<T>,
T: 'a,
fn pipe_as_mut<'a, T, R>(&'a mut self, func: impl FnOnce(&'a mut T) -> R) -> R where
R: 'a,
Self: AsMut<T>,
T: 'a,
R: 'a,
Self: AsMut<T>,
T: 'a,
impl<T> PipeBorrow for T
fn pipe_borrow<'a, T, R>(&'a self, func: impl FnOnce(&'a T) -> R) -> R where
R: 'a,
Self: Borrow<T>,
T: 'a,
R: 'a,
Self: Borrow<T>,
T: 'a,
fn pipe_borrow_mut<'a, T, R>(
&'a mut self,
func: impl FnOnce(&'a mut T) -> R
) -> R where
R: 'a,
Self: BorrowMut<T>,
T: 'a,
&'a mut self,
func: impl FnOnce(&'a mut T) -> R
) -> R where
R: 'a,
Self: BorrowMut<T>,
T: 'a,
impl<T> PipeDeref for T
fn pipe_deref<'a, R>(&'a self, func: impl FnOnce(&'a Self::Target) -> R) -> R where
R: 'a,
Self: Deref,
R: 'a,
Self: Deref,
fn pipe_deref_mut<'a, R>(
&'a mut self,
func: impl FnOnce(&'a mut Self::Target) -> R
) -> R where
R: 'a,
Self: DerefMut,
&'a mut self,
func: impl FnOnce(&'a mut Self::Target) -> R
) -> R where
R: 'a,
Self: DerefMut,
impl<T> PipeRef for T
fn pipe_ref<'a, R>(&'a self, func: impl FnOnce(&'a Self) -> R) -> R where
R: 'a,
R: 'a,
fn pipe_mut<'a, R>(&'a mut self, func: impl FnOnce(&'a mut Self) -> R) -> R where
R: 'a,
R: 'a,
impl<T> Tap for T
fn tap(self, func: impl FnOnce(&Self)) -> Self
fn tap_mut(self, func: impl FnOnce(&mut Self)) -> Self
fn tap_borrow<B>(self, func: impl FnOnce(&B)) -> Self where
B: ?Sized,
Self: Borrow<B>,
B: ?Sized,
Self: Borrow<B>,
fn tap_borrow_mut<B>(self, func: impl FnOnce(&mut B)) -> Self where
B: ?Sized,
Self: BorrowMut<B>,
B: ?Sized,
Self: BorrowMut<B>,
fn tap_ref<R>(self, func: impl FnOnce(&R)) -> Self where
R: ?Sized,
Self: AsRef<R>,
R: ?Sized,
Self: AsRef<R>,
fn tap_ref_mut<R>(self, func: impl FnOnce(&mut R)) -> Self where
R: ?Sized,
Self: AsMut<R>,
R: ?Sized,
Self: AsMut<R>,
fn tap_deref<T>(self, func: impl FnOnce(&T)) -> Self where
Self: Deref<Target = T>,
T: ?Sized,
Self: Deref<Target = T>,
T: ?Sized,
fn tap_deref_mut<T>(self, func: impl FnOnce(&mut T)) -> Self where
Self: DerefMut<Target = T> + Deref,
T: ?Sized,
Self: DerefMut<Target = T> + Deref,
T: ?Sized,
fn tap_dbg(self, func: impl FnOnce(&Self)) -> Self
fn tap_mut_dbg(self, func: impl FnOnce(&mut Self)) -> Self
fn tap_borrow_dbg<B>(self, func: impl FnOnce(&B)) -> Self where
B: ?Sized,
Self: Borrow<B>,
B: ?Sized,
Self: Borrow<B>,
fn tap_borrow_mut_dbg<B>(self, func: impl FnOnce(&mut B)) -> Self where
B: ?Sized,
Self: BorrowMut<B>,
B: ?Sized,
Self: BorrowMut<B>,
fn tap_ref_dbg<R>(self, func: impl FnOnce(&R)) -> Self where
R: ?Sized,
Self: AsRef<R>,
R: ?Sized,
Self: AsRef<R>,
fn tap_ref_mut_dbg<R>(self, func: impl FnOnce(&mut R)) -> Self where
R: ?Sized,
Self: AsMut<R>,
R: ?Sized,
Self: AsMut<R>,
fn tap_deref_dbg<T>(self, func: impl FnOnce(&T)) -> Self where
Self: Deref<Target = T>,
T: ?Sized,
Self: Deref<Target = T>,
T: ?Sized,
fn tap_deref_mut_dbg<T>(self, func: impl FnOnce(&mut T)) -> Self where
Self: DerefMut<Target = T> + Deref,
T: ?Sized,
Self: DerefMut<Target = T> + Deref,
T: ?Sized,
impl<T> Tap for T
fn tap<F, R>(self, func: F) -> Self where
F: FnOnce(&Self) -> R,
F: FnOnce(&Self) -> R,
fn tap_dbg<F, R>(self, func: F) -> Self where
F: FnOnce(&Self) -> R,
F: FnOnce(&Self) -> R,
fn tap_mut<F, R>(self, func: F) -> Self where
F: FnOnce(&mut Self) -> R,
F: FnOnce(&mut Self) -> R,
fn tap_mut_dbg<F, R>(self, func: F) -> Self where
F: FnOnce(&mut Self) -> R,
F: FnOnce(&mut Self) -> R,
impl<T, U> TapAsRef<U> for T where
U: ?Sized,
U: ?Sized,
fn tap_ref<F, R>(self, func: F) -> Self where
F: FnOnce(&T) -> R,
Self: AsRef<T>,
F: FnOnce(&T) -> R,
Self: AsRef<T>,
fn tap_ref_dbg<F, R>(self, func: F) -> Self where
F: FnOnce(&T) -> R,
Self: AsRef<T>,
F: FnOnce(&T) -> R,
Self: AsRef<T>,
fn tap_ref_mut<F, R>(self, func: F) -> Self where
F: FnOnce(&mut T) -> R,
Self: AsMut<T>,
F: FnOnce(&mut T) -> R,
Self: AsMut<T>,
fn tap_ref_mut_dbg<F, R>(self, func: F) -> Self where
F: FnOnce(&mut T) -> R,
Self: AsMut<T>,
F: FnOnce(&mut T) -> R,
Self: AsMut<T>,
impl<T, U> TapBorrow<U> for T where
U: ?Sized,
U: ?Sized,
fn tap_borrow<F, R>(self, func: F) -> Self where
F: FnOnce(&T) -> R,
Self: Borrow<T>,
F: FnOnce(&T) -> R,
Self: Borrow<T>,
fn tap_borrow_dbg<F, R>(self, func: F) -> Self where
F: FnOnce(&T) -> R,
Self: Borrow<T>,
F: FnOnce(&T) -> R,
Self: Borrow<T>,
fn tap_borrow_mut<F, R>(self, func: F) -> Self where
F: FnOnce(&mut T) -> R,
Self: BorrowMut<T>,
F: FnOnce(&mut T) -> R,
Self: BorrowMut<T>,
fn tap_borrow_mut_dbg<F, R>(self, func: F) -> Self where
F: FnOnce(&mut T) -> R,
Self: BorrowMut<T>,
F: FnOnce(&mut T) -> R,
Self: BorrowMut<T>,
impl<T> TapDeref for T
fn tap_deref<F, R>(self, func: F) -> Self where
F: FnOnce(&Self::Target) -> R,
Self: Deref,
F: FnOnce(&Self::Target) -> R,
Self: Deref,
fn tap_deref_dbg<F, R>(self, func: F) -> Self where
F: FnOnce(&Self::Target) -> R,
Self: Deref,
F: FnOnce(&Self::Target) -> R,
Self: Deref,
fn tap_deref_mut<F, R>(self, func: F) -> Self where
F: FnOnce(&mut Self::Target) -> R,
Self: DerefMut,
F: FnOnce(&mut Self::Target) -> R,
Self: DerefMut,
fn tap_deref_mut_dbg<F, R>(self, func: F) -> Self where
F: FnOnce(&mut Self::Target) -> R,
Self: DerefMut,
F: FnOnce(&mut Self::Target) -> R,
Self: DerefMut,
impl<T> ToOwned for T where
T: Clone,
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T: Clone,
type Owned = T
The resulting type after obtaining ownership.
pub fn to_owned(&self) -> T
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pub fn clone_into(&self, target: &mut T)
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impl<T> ToString for T where
T: Display + ?Sized,
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T: Display + ?Sized,
impl<T> TryConv for T
impl<T> TryConv for T
impl<T, U> TryFrom<U> for T where
U: Into<T>,
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U: Into<T>,
type Error = Infallible
The type returned in the event of a conversion error.
pub fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
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impl<T, U> TryInto<U> for T where
U: TryFrom<T>,
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U: TryFrom<T>,