Struct MetaItem

pub struct MetaItem {
    pub unsafety: Safety,
    pub path: Path,
    pub kind: MetaItemKind,
    pub span: Span,
}

A semantic representation of a meta item. A meta item is a slightly restricted form of an attribute – it can only contain expressions in certain leaf positions, rather than arbitrary token streams – that is used for most built-in attributes.

E.g., #[test], #[derive(..)], #[rustfmt::skip] or #[feature = "foo"].

Fields

unsafety: Safety

path: Path

kind: MetaItemKind

span: Span

Implementations

impl MetaItem

pub fn ident(&self) -> Option<Ident>

For a single-segment meta item, returns its name; otherwise, returns None.

pub fn name_or_empty(&self) -> Symbol

pub fn has_name(&self, name: Symbol) -> bool

pub fn is_word(&self) -> bool

pub fn meta_item_list(&self) -> Option<&[MetaItemInner]>

pub fn name_value_literal(&self) -> Option<&MetaItemLit>

Example:
    #[attribute(name = "value")]
                ^^^^^^^^^^^^^^

pub fn name_value_literal_span(&self) -> Option<Span>

This is used in case you want the value span instead of the whole attribute. Example:

#[doc(alias = "foo")]

In here, it’ll return a span for "foo".

pub fn value_str(&self) -> Option<Symbol>

Returns the string value in:

#[attribute = "value"]
              ^^^^^^^

It returns None in any other cases like:

#[attr("value")]

fn from_tokens<'a, I>(tokens: &mut Peekable<I>) -> Option<MetaItem>

where I: Iterator<Item = &'a TokenTree>,

Trait Implementations

impl Clone for MetaItem

fn clone(&self) -> MetaItem

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for MetaItem

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

Formats the value using the given formatter.

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

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

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

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

impl<__CTX> HashStable<__CTX> for MetaItem

where __CTX: HashStableContext,

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

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: 88 bytes