Enum rustc_expand::mbe::metavar_expr::MetaVarExpr

pub(crate) enum MetaVarExpr {
    Concat(Box<[MetaVarExprConcatElem]>),
    Count(Ident, usize),
    Ignore(Ident),
    Index(usize),
    Len(usize),
}

A meta-variable expression, for expansions based on properties of meta-variables.

Variants

Concat(Box<[MetaVarExprConcatElem]>)

Unification of two or more identifiers.

Count(Ident, usize)

The number of repetitions of an identifier.

Ignore(Ident)

Ignore a meta-variable for repetition without expansion.

Index(usize)

The index of the repetition at a particular depth, where 0 is the inner-most repetition. The usize is the depth.

Len(usize)

The length of the repetition at a particular depth, where 0 is the inner-most repetition. The usize is the depth.

Implementations

impl MetaVarExpr

pub(crate) fn parse<'psess>( input: &TokenStream, outer_span: Span, psess: &'psess ParseSess, ) -> PResult<'psess, MetaVarExpr>

Attempt to parse a meta-variable expression from a token stream.

pub(crate) fn for_each_metavar<A>( &self, aux: A, cb: impl FnMut(A, &Ident) -> A, ) -> A

Trait Implementations

impl Debug for MetaVarExpr

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

Formats the value using the given formatter.

impl<__D: SpanDecoder> Decodable<__D> for MetaVarExpr

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

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

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

impl PartialEq for MetaVarExpr

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

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

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

impl StructuralPartialEq for MetaVarExpr

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: 24 bytes

Size for each variant:

• Concat: 20 bytes
• Count: 20 bytes
• Ignore: 12 bytes
• Index: 12 bytes
• Len: 12 bytes