Enum Arg 

pub enum Arg {
    Flag(Ident),
    Expr(Ident, Expr),
    List(Ident, Args),
    Lit(Lit),
}

A single parsed attribute argument.

Represents one of four forms: a bare flag (skip), a key-value expression (rename = "foo"), a nested list (serde(flatten)), or a standalone literal ("hello").

Variants

Flag(Ident)

Expr(Ident, Expr)

List(Ident, Args)

Lit(Lit)

Implementations

impl Arg

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

Returns the name of this argument, or None for standalone literals.

pub fn is_flag(&self) -> bool

Returns true if this is a bare flag (e.g. skip).

pub fn is_expr(&self) -> bool

Returns true if this is a key-value expression (e.g. rename = "foo").

pub fn is_list(&self) -> bool

Returns true if this is a nested list (e.g. serde(flatten)).

pub fn is_lit(&self) -> bool

Returns true if this is a standalone literal.

pub fn as_expr(&self) -> &Expr

Returns the expression value. Panics if not an Expr variant.

pub fn as_args(&self) -> &Args

Returns the nested args. Panics if not a List variant.

pub fn as_lit(&self) -> &Lit

Returns the literal value. Panics if not a Lit variant.

pub fn as_flag(&self) -> &Ident

Returns the flag identifier. Panics if not a Flag variant.

pub fn as_str(&self) -> String

Extracts the string value. Panics if the value is not a string literal.

pub fn as_int<T: FromStr>(&self) -> T

where T::Err: Display,

Parses the integer value. Panics if the value is not an integer literal.

pub fn as_float<T: FromStr>(&self) -> T

where T::Err: Display,

Parses the float value. Panics if the value is not a float literal.

pub fn as_char(&self) -> char

Extracts the char value. Panics if the value is not a char literal.

pub fn as_expr_lit(&self) -> Option<&Lit>

Returns the literal if this is a Lit or an Expr containing a literal.

pub fn as_bool(&self) -> bool

Extracts the bool value. Panics if the value is not a bool literal.

Trait Implementations

impl Clone for Arg

fn clone(&self) -> Arg

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Parse for Arg

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

impl ToTokens for Arg

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) -> TokenStream

where Self: Sized,

Convert self directly into a TokenStream object.