Enum proc_macro::Spacing

1.29.0 · source ·
pub enum Spacing {
    Joint,
    Alone,
}
Expand description

Indicates whether a Punct token can join with the following token to form a multi-character operator.

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§1.29.0

Joint

A Punct token can join with the following token to form a multi-character operator.

In token streams constructed using proc macro interfaces, Joint punctuation tokens can be followed by any other tokens. However, in token streams parsed from source code, the compiler will only set spacing to Joint in the following cases.

  • When a Punct is immediately followed by another Punct without a whitespace. E.g. + is Joint in += and ++.
  • When a single quote ' is immediately followed by an identifier without a whitespace. E.g. ' is Joint in 'lifetime.

This list may be extended in the future to enable more token combinations.

§1.29.0

Alone

A Punct token cannot join with the following token to form a multi-character operator.

Alone punctuation tokens can be followed by any other tokens. In token streams parsed from source code, the compiler will set spacing to Alone in all cases not covered by the conditions for Joint above. E.g. + is Alone in + =, +ident and +(). In particular, tokens not followed by anything will be marked as Alone.

Trait Implementations§

1.29.0 · source§

impl Clone for Spacing

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fn clone(&self) -> Spacing

Returns a copy of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
1.29.0 · source§

impl Debug for Spacing

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

Formats the value using the given formatter. Read more
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impl PartialEq for Spacing

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

Tests for self and other values to be equal, and is used by ==.
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fn ne(&self, other: &Rhs) -> bool

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

impl Copy for Spacing

1.29.0 · source§

impl Eq for Spacing

1.29.0 · source§

impl StructuralPartialEq for Spacing

Auto Trait Implementations§

Blanket Implementations§

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

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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

Mutably borrows from an owned value. Read more
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impl<T> CloneToUninit for T
where T: Clone,

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unsafe fn clone_to_uninit(&self, dst: *mut T)

🔬This is a nightly-only experimental API. (clone_to_uninit #126799)
Performs copy-assignment from self to dst. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.