Enum syn::Meta

pub enum Meta {
    Path(Path),
    List(MetaList),
    NameValue(MetaNameValue),
}

Content of a compile-time structured attribute.

Path

A meta path is like the test in #[test].

List

A meta list is like the derive(Copy) in #[derive(Copy)].

NameValue

A name-value meta is like the path = "..." in #[path = "sys/windows.rs"].

Syntax tree enum

This type is a syntax tree enum.

Variants

Path(Path)

List(MetaList)

A structured list within an attribute, like derive(Copy, Clone).

NameValue(MetaNameValue)

A name-value pair within an attribute, like feature = "nightly".

Implementations

impl Meta

pub fn path(&self) -> &Path

Returns the path that begins this structured meta item.

For example this would return the test in #[test], the derive in #[derive(Copy)], and the path in #[path = "sys/windows.rs"].

pub fn require_path_only(&self) -> Result<&Path>

Error if this is a Meta::List or Meta::NameValue.

pub fn require_list(&self) -> Result<&MetaList>

Error if this is a Meta::Path or Meta::NameValue.

pub fn require_name_value(&self) -> Result<&MetaNameValue>

Error if this is a Meta::Path or Meta::List.

Trait Implementations

impl Clone for Meta

fn clone(&self) -> Self

Returns a copy of the value.

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

Performs copy-assignment from source.

impl From<MetaList> for Meta

fn from(e: MetaList) -> Meta

Converts to this type from the input type.

impl From<MetaNameValue> for Meta

fn from(e: MetaNameValue) -> Meta

Converts to this type from the input type.

impl From<Path> for Meta

fn from(e: Path) -> Meta

Converts to this type from the input type.

impl Parse for Meta

fn parse(input: ParseStream<'_>) -> Result<Self>

impl ToTokens for Meta

fn to_tokens(&self, tokens: &mut TokenStream)

Write self to the given TokenStream.

fn to_token_stream(&self) -> TokenStream

Convert self directly into a TokenStream object.

fn into_token_stream(self) -> TokenStreamwhere Self: Sized,

Convert self directly into a TokenStream object.