Trait CombineAttributeParser

pub(crate) trait CombineAttributeParser<S: Stage>: 'static {
    type Item;

    const PATH: &[Symbol];
    const CONVERT: fn(ThinVec<Self::Item>) -> AttributeKind;
    const TEMPLATE: AttributeTemplate;

    // Required method
    fn extend<'c>(
        cx: &'c mut AcceptContext<'_, '_, S>,
        args: &'c ArgParser<'_>,
    ) -> impl IntoIterator<Item = Self::Item> + 'c;
}

Alternative to AttributeParser that automatically handles state management. If multiple attributes appear on an element, combines the values of each into a ThinVec. Combine<T> where T: CombineAttributeParser implements AttributeParser.

CombineAttributeParser can only convert a single kind of attribute, and cannot combine multiple attributes together like is necessary for #[stable()] and #[unstable()] for example.

Required Associated Constants

const PATH: &[Symbol]

const CONVERT: fn(ThinVec<Self::Item>) -> AttributeKind

A function that converts individual items (of type Item) into the final attribute.

For example, individual representations fomr #[repr(...)] attributes into an AttributeKind::Repr(x), where x is a vec of these individual reprs.

const TEMPLATE: AttributeTemplate

The template this attribute parser should implement. Used for diagnostics.

Required Associated Types

type Item

Required Methods

fn extend<'c>( cx: &'c mut AcceptContext<'_, '_, S>, args: &'c ArgParser<'_>, ) -> impl IntoIterator<Item = Self::Item> + 'c

Converts a single syntactical attribute to a number of elements of the semantic attribute, or AttributeKind

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors

impl<S: Stage> CombineAttributeParser<S> for AllowConstFnUnstableParser

const PATH: &[Symbol]

const CONVERT: fn(ThinVec<Self::Item>) -> AttributeKind = {rustc_attr_data_structures::AttributeKind::AllowConstFnUnstable as fn(thin_vec::ThinVec<<attributes::allow_unstable::AllowConstFnUnstableParser as attributes::CombineAttributeParser<S>>::Item>) -> rustc_attr_data_structures::AttributeKind}

const TEMPLATE: AttributeTemplate

type Item = Symbol

impl<S: Stage> CombineAttributeParser<S> for AllowInternalUnstableParser

const PATH: &[Symbol]

const CONVERT: fn(ThinVec<Self::Item>) -> AttributeKind = {rustc_attr_data_structures::AttributeKind::AllowInternalUnstable as fn(thin_vec::ThinVec<<attributes::allow_unstable::AllowInternalUnstableParser as attributes::CombineAttributeParser<S>>::Item>) -> rustc_attr_data_structures::AttributeKind}

const TEMPLATE: AttributeTemplate

type Item = (Symbol, Span)

impl<S: Stage> CombineAttributeParser<S> for ReprParser

const PATH: &[Symbol]

const CONVERT: fn(ThinVec<Self::Item>) -> AttributeKind = {rustc_attr_data_structures::AttributeKind::Repr as fn(thin_vec::ThinVec<<attributes::repr::ReprParser as attributes::CombineAttributeParser<S>>::Item>) -> rustc_attr_data_structures::AttributeKind}

const TEMPLATE: AttributeTemplate

type Item = (ReprAttr, Span)