Enum Attr 

pub enum Attr {
    Singular(SingularAttr),
    Parametrized(ParametrizedAttr),
}

Internal structure representation of a proc macro attribute collected instances having some specific name (accessible via Attr::name()).

Variants

Singular(SingularAttr)

Attribute of #[attr] or #[attr = value] form, which, aside from the case where value is a string literal, may have only a single occurrence (string literals are concatenated into a single value like rust compiler does for #[doc = "..."] attributes).

Parametrized(ParametrizedAttr)

Parametrized attribute in form of #[attr(...)], where parameters are gathered from all attribute occurrences.

Implementations

impl Attr

pub fn with( name: impl ToString + AsRef<str>, attrs: &[Attribute], ) -> Result<Self, Error>

Constructs Attr from a vector of all syn-parsed attributes, selecting attributes matching the provided name.

pub fn from_attribute(attr: &Attribute) -> Result<Self, Error>

Constructor parsing Attribute value and returning either SingularAttr or ParametrizedAttr packed in form of Attr enum.

If the attribute does not match either of forms, a Error is returned. Currently, only single type of error may occur in practice:

• Error::ArgNameMustBeIdent, which happens if the attribute name is not an syn::Ident but is a complex path value

pub fn try_singular(self) -> Result<SingularAttr, Error>

Returns inner value \in form of SingularAttr for Attr::Singular variant, or fails with Error::SingularAttrRequired otherwise

pub fn try_parametrized(self) -> Result<ParametrizedAttr, Error>

Returns inner value \in form of ParametrizedAttr for Attr::Parametrized variant, or fails with Error::ParametrizedAttrRequired otherwise

pub fn name(&self) -> &str

Returns string reference to the argument name

pub fn arg_value(&self) -> Result<ArgValue, Error>

Returns ArgValue for the Attr::Singular variant or fails with Error::ParametrizedAttrHasNoValue

pub fn literal_value(&self) -> Result<Lit, Error>

Returns literal value for the Attr::Singular variant or fails with Error::ParametrizedAttrHasNoValue. See ArgValue::to_literal_value for more details.

pub fn type_value(&self) -> Result<Type, Error>

Returns type value for the Attr::Singular variant or fails with Error::ParametrizedAttrHasNoValue. See ArgValue::to_literal_value for more details.

Trait Implementations

impl Clone for Attr

fn clone(&self) -> Attr

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Attr

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

Formats the value using the given formatter.

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: 288 bytes

Size for each variant:

• Singular: 288 bytes
• Parametrized: 200 bytes