Enum amplify_syn::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 copy 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.