pub enum TokenTree {
    Token(TokenSpacing),
    Delimited(DelimSpanDelimiterTokenStream),
}
Expand description

When the main Rust parser encounters a syntax-extension invocation, it parses the arguments to the invocation as a token tree. This is a very loose structure, such that all sorts of different AST fragments can be passed to syntax extensions using a uniform type.

If the syntax extension is an MBE macro, it will attempt to match its LHS token tree against the provided token tree, and if it finds a match, will transcribe the RHS token tree, splicing in any captured macro_parser::matched_nonterminals into the SubstNts it finds.

The RHS of an MBE macro is the only place SubstNts are substituted. Nothing special happens to misnamed or misplaced SubstNts.

Variants§

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Token(TokenSpacing)

A single token.

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Delimited(DelimSpanDelimiterTokenStream)

A delimited sequence of token trees.

Implementations§

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impl TokenTree

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pub fn eq_unspanned(&self, other: &TokenTree) -> bool

Checks if this TokenTree is equal to the other, regardless of span information.

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pub fn span(&self) -> Span

Retrieves the TokenTree’s span.

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pub fn set_span(&mut self, span: Span)

Modify the TokenTree’s span in-place.

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pub fn token_alone(kind: TokenKind, span: Span) -> TokenTree

Create a TokenTree::Token with alone spacing.

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pub fn token_joint(kind: TokenKind, span: Span) -> TokenTree

Create a TokenTree::Token with joint spacing.

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pub fn uninterpolate(self) -> TokenTree

Trait Implementations§

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impl Clone for TokenTree

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fn clone(&self) -> TokenTree

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 TokenTree

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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: Decoder> Decodable<__D> for TokenTree

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

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impl<__E: Encoder> Encodable<__E> for TokenTree

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

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impl FromIterator<TokenTree> for TokenStream

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fn from_iter<I: IntoIterator<Item = TokenTree>>(iter: I) -> Self

Creates a value from an iterator. Read more
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impl<__CTX> HashStable<__CTX> for TokenTreewhere
    __CTX: HashStableContext,

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

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impl PartialEq<TokenTree> for TokenTree

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

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

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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impl StructuralPartialEq for TokenTree

Auto Trait Implementations§

Blanket Implementations§

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impl<T> Any for Twhere
    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 Twhere
    T: ?Sized,

const: unstable · source§

fn borrow(&self) -> &T

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

const: unstable · source§

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

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

const: unstable · source§

fn from(t: T) -> T

Returns the argument unchanged.

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

const: unstable · source§

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 Twhere
    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 Twhere
    U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
const: unstable · source§

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 Twhere
    U: TryFrom<T>,

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

The type returned in the event of a conversion error.
const: unstable · source§

fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.

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: 32 bytes

Size for each variant:

  • Token: 31 bytes
  • Delimited: 31 bytes