Enum proc_macro::Delimiter

pub enum Delimiter {
    Parenthesis,
    Brace,
    Bracket,
    None,
}

Describes how a sequence of token trees is delimited.

Variants

Parenthesis

( ... )

Brace

{ ... }

Bracket

[ ... ]

None

∅ ... ∅ An invisible delimiter, that may, for example, appear around tokens coming from a “macro variable” $var. It is important to preserve operator priorities in cases like $var * 3 where $var is 1 + 2. Invisible delimiters might not survive roundtrip of a token stream through a string.

Note: rustc currently can ignore the grouping of tokens delimited by None in the output of a proc_macro. Only None-delimited groups created by a macro_rules macro in the input of a proc_macro macro are preserved, and only in very specific circumstances. Any None-delimited groups (re)created by a proc_macro will therefore not preserve operator priorities as indicated above. The other Delimiter variants should be used instead in this context. This is a rustc bug. For details, see rust-lang/rust#67062.

Trait Implementations

impl Clone for Delimiter

fn clone(&self) -> Delimiter

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Delimiter

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

Formats the value using the given formatter.

impl PartialEq for Delimiter

fn eq(&self, other: &Delimiter) -> 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 Copy for Delimiter

impl Eq for Delimiter

impl StructuralPartialEq for Delimiter