Enum rustc_expand::mbe::transcribe::LockstepIterSize

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enum LockstepIterSize {
    Unconstrained,
    Constraint(usize, MacroRulesNormalizedIdent),
    Contradiction(String),
}
Expand description

An accumulator over a TokenTree to be used with fold. During transcription, we need to make sure that the size of each sequence and all of its nested sequences are the same as the sizes of all the matched (nested) sequences in the macro invocation. If they don’t match, somebody has made a mistake (either the macro writer or caller).

Variants§

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Unconstrained

No constraints on length of matcher. This is true for any TokenTree variants except a MetaVar with an actual MatchedSeq (as opposed to a MatchedNonterminal).

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Constraint(usize, MacroRulesNormalizedIdent)

A MetaVar with an actual MatchedSeq. The length of the match and the name of the meta-var are returned.

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Contradiction(String)

Two Constraints on the same sequence had different lengths. This is an error.

Implementations§

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impl LockstepIterSize

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fn with(self, other: LockstepIterSize) -> LockstepIterSize

Find incompatibilities in matcher/invocation sizes.

  • Unconstrained is compatible with everything.
  • Contradiction is incompatible with everything.
  • Constraint(len) is only compatible with other constraints of the same length.

Trait Implementations§

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impl Clone for LockstepIterSize

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fn clone(&self) -> LockstepIterSize

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<T> Aligned for T

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const ALIGN: Alignment = _

Alignment of Self.
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where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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fn borrow_mut(&mut self) -> &mut T

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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)
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fn collect_and_apply<I, F>(iter: I, f: F) -> R
where I: Iterator<Item = T>, F: FnOnce(&[T]) -> R,

Equivalent to f(&iter.collect::<Vec<_>>()).

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type Output = R

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fn filterable( self, filter_name: &'static str, ) -> RequestFilterDataProvider<T, fn(_: DataRequest<'_>) -> bool>

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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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Calls U::from(self).

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

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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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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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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:

  • Unconstrained: 0 bytes
  • Constraint: 20 bytes
  • Contradiction: 28 bytes