Struct syn::Attribute [−][src]
pub struct Attribute { pub pound_token: Pound, pub style: AttrStyle, pub bracket_token: Bracket, pub path: Path, pub tts: TokenStream, }
An attribute like #[repr(transparent)]
.
This type is available if Syn is built with the "derive"
or "full"
feature.
Syntax
Rust has six types of attributes.
- Outer attributes like
#[repr(transparent)]
. These appear outside or in front of the item they describe. - Inner attributes like
#![feature(proc_macro)]
. These appear inside of the item they describe, usually a module. - Outer doc comments like
/// # Example
. - Inner doc comments like
//! Please file an issue
. - Outer block comments
/** # Example */
. - Inner block comments
/*! Please file an issue */
.
The style
field of type AttrStyle
distinguishes whether an attribute
is outer or inner. Doc comments and block comments are promoted to
attributes, as this is how they are processed by the compiler and by
macro_rules!
macros.
The path
field gives the possibly colon-delimited path against which
the attribute is resolved. It is equal to "doc"
for desugared doc
comments. The tts
field contains the rest of the attribute body as
tokens.
#[derive(Copy)] #[crate::precondition x < 5]
^^^^^^~~~~~~ ^^^^^^^^^^^^^^^^^^^ ~~~~~
path tts path tts
Use the interpret_meta
method to try parsing the tokens of an
attribute into the structured representation that is used by convention
across most Rust libraries.
Parsing
This type does not implement the Parse
trait and thus cannot be
parsed directly by ParseStream::parse
. Instead use
ParseStream::call
with one of the two parser functions
Attribute::parse_outer
or Attribute::parse_inner
depending on
which you intend to parse.
#[macro_use] extern crate syn; use syn::{Attribute, Ident}; use syn::parse::{Parse, ParseStream, Result}; // Parses a unit struct with attributes. // // #[path = "s.tmpl"] // struct S; struct UnitStruct { attrs: Vec<Attribute>, struct_token: Token![struct], name: Ident, semi_token: Token![;], } impl Parse for UnitStruct { fn parse(input: ParseStream) -> Result<Self> { Ok(UnitStruct { attrs: input.call(Attribute::parse_outer)?, struct_token: input.parse()?, name: input.parse()?, semi_token: input.parse()?, }) } }
Fields
pound_token: Pound
style: AttrStyle
bracket_token: Bracket
path: Path
tts: TokenStream
Methods
impl Attribute
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impl Attribute
pub fn parse_meta(&self) -> Result<Meta>
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pub fn parse_meta(&self) -> Result<Meta>
Parses the tokens after the path as a Meta
if
possible.
pub fn parse_outer(input: ParseStream) -> Result<Vec<Self>>
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pub fn parse_outer(input: ParseStream) -> Result<Vec<Self>>
Parses zero or more outer attributes from the stream.
This function is available if Syn is built with the "parsing"
feature.
pub fn parse_inner(input: ParseStream) -> Result<Vec<Self>>
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pub fn parse_inner(input: ParseStream) -> Result<Vec<Self>>
Parses zero or more inner attributes from the stream.
This function is available if Syn is built with the "parsing"
feature.
Trait Implementations
impl ToTokens for Attribute
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impl ToTokens for Attribute
fn to_tokens(&self, tokens: &mut TokenStream)
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fn to_tokens(&self, tokens: &mut TokenStream)
Write self
to the given TokenStream
. Read more
fn into_token_stream(self) -> TokenStream
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fn into_token_stream(self) -> TokenStream
Convert self
directly into a TokenStream
object. Read more
impl Debug for Attribute
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impl Debug for Attribute
fn fmt(&self, f: &mut Formatter) -> Result
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fn fmt(&self, f: &mut Formatter) -> Result
Formats the value using the given formatter. Read more
impl Clone for Attribute
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impl Clone for Attribute
fn clone(&self) -> Attribute
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fn clone(&self) -> Attribute
Returns a copy of the value. Read more
fn clone_from(&mut self, source: &Self)
1.0.0[src]
fn clone_from(&mut self, source: &Self)
Performs copy-assignment from source
. Read more
impl Eq for Attribute
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impl Eq for Attribute
impl PartialEq for Attribute
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impl PartialEq for Attribute
fn eq(&self, other: &Self) -> bool
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fn eq(&self, other: &Self) -> bool
This method tests for self
and other
values to be equal, and is used by ==
. Read more
fn ne(&self, other: &Rhs) -> bool
1.0.0[src]
fn ne(&self, other: &Rhs) -> bool
This method tests for !=
.
impl Hash for Attribute
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impl Hash for Attribute