rustc_ast::tokenstream

Enum Spacing

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pub enum Spacing {
    Alone,
    Joint,
    JointHidden,
}
Expand description

Indicates whether a token can join with the following token to form a compound token. Used for conversions to proc_macro::Spacing. Also used to guide pretty-printing, which is where the JointHidden value (which isn’t part of proc_macro::Spacing) comes in useful.

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Alone

The token cannot join with the following token to form a compound token.

In token streams parsed from source code, the compiler will use Alone for any token immediately followed by whitespace, a non-doc comment, or EOF.

When constructing token streams within the compiler, use this for each token that (a) should be pretty-printed with a space after it, or (b) is the last token in the stream. (In the latter case the choice of spacing doesn’t matter because it is never used for the last token. We arbitrarily use Alone.)

Converts to proc_macro::Spacing::Alone, and proc_macro::Spacing::Alone converts back to this.

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Joint

The token can join with the following token to form a compound token.

In token streams parsed from source code, the compiler will use Joint for any token immediately followed by punctuation (as determined by Token::is_punct).

When constructing token streams within the compiler, use this for each token that (a) should be pretty-printed without a space after it, and (b) is followed by a punctuation token.

Converts to proc_macro::Spacing::Joint, and proc_macro::Spacing::Joint converts back to this.

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JointHidden

The token can join with the following token to form a compound token, but this will not be visible at the proc macro level. (This is what the Hidden means; see below.)

In token streams parsed from source code, the compiler will use JointHidden for any token immediately followed by anything not covered by the Alone and Joint cases: an identifier, lifetime, literal, delimiter, doc comment.

When constructing token streams, use this for each token that (a) should be pretty-printed without a space after it, and (b) is followed by a non-punctuation token.

Converts to proc_macro::Spacing::Alone, but proc_macro::Spacing::Alone converts back to token::Spacing::Alone. Because of that, pretty-printing of TokenStreams produced by proc macros is unavoidably uglier (with more whitespace between tokens) than pretty-printing of TokenStream’s produced by other means (i.e. parsed source code, internally constructed token streams, and token streams produced by declarative macros).

Trait Implementations§

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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
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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<__D: SpanDecoder> Decodable<__D> for Spacing

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fn decode(__decoder: &mut __D) -> Self

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impl<__E: SpanEncoder> Encodable<__E> for Spacing

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fn encode(&self, __encoder: &mut __E)

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impl<__CTX> HashStable<__CTX> for Spacing
where __CTX: HashStableContext,

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fn hash_stable(&self, __hcx: &mut __CTX, __hasher: &mut StableHasher)

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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.
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impl Copy for Spacing

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impl StructuralPartialEq for Spacing

Auto Trait Implementations§

Blanket Implementations§

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impl<T> Aligned for T

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const ALIGN: Alignment = _

Alignment of Self.
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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)
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> Instrument for T

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fn instrument(self, span: Span) -> Instrumented<Self>

Instruments this type with the provided Span, returning an Instrumented wrapper. Read more
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fn in_current_span(self) -> Instrumented<Self>

Instruments this type with the current Span, returning an Instrumented wrapper. Read more
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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> IntoEither for T

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fn into_either(self, into_left: bool) -> Either<Self, Self>

Converts self into a Left variant of Either<Self, Self> if into_left is true. Converts self into a Right variant of Either<Self, Self> otherwise. Read more
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fn into_either_with<F>(self, into_left: F) -> Either<Self, Self>
where F: FnOnce(&Self) -> bool,

Converts self into a Left variant of Either<Self, Self> if into_left(&self) returns true. Converts self into a Right variant of Either<Self, Self> otherwise. Read more
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impl<T> Pointable for T

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const ALIGN: usize = _

The alignment of pointer.
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type Init = T

The type for initializers.
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unsafe fn init(init: <T as Pointable>::Init) -> usize

Initializes a with the given initializer. Read more
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unsafe fn deref<'a>(ptr: usize) -> &'a T

Dereferences the given pointer. Read more
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unsafe fn deref_mut<'a>(ptr: usize) -> &'a mut T

Mutably dereferences the given pointer. Read more
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unsafe fn drop(ptr: usize)

Drops the object pointed to by the given pointer. Read more
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impl<T> Same for T

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type Output = T

Should always be Self
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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.
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impl<T> WithSubscriber for T

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fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self>
where S: Into<Dispatch>,

Attaches the provided Subscriber to this type, returning a WithDispatch wrapper. Read more
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fn with_current_subscriber(self) -> WithDispatch<Self>

Attaches the current default Subscriber to this type, returning a WithDispatch wrapper. Read more
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impl<'a, T> Captures<'a> for T
where T: ?Sized,

Layout§

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

Size: 1 byte

Size for each variant:

  • Alone: 0 bytes
  • Joint: 0 bytes
  • JointHidden: 0 bytes