Struct amplify_syn::ParametrizedAttr

pub struct ParametrizedAttr {
    pub name: String,
    pub args: HashMap<String, ArgValue>,
    pub paths: Vec<Path>,
    pub string: Option<LitStr>,
    pub bytes: Option<LitByteStr>,
    pub chars: Vec<LitChar>,
    pub integers: Vec<LitInt>,
    pub floats: Vec<LitFloat>,
    pub bool: Option<LitBool>,
}

Representation for all allowed forms of #[attr(...)] attribute. If attribute has a multiple occurrences they are all assembled into a single list. Repeated named arguments are not allowed and result in errors.

For situations like in #[attr("string literal")], ParametrizedAttr will have a name field set to attr, literal field set to Lit::LitStr(LitStr("string literal")), args will be an empty HashSet and paths will be represented by an empty vector.

Fields

name: String

Attribute name - attr part of #[attr(...)]

args: HashMap<String, ArgValue>

All attribute arguments that have form of #[attr(ident = "literal")] or #[attr(ident = TypeName)] mapped to their name identifiers.

paths: Vec<Path>

All attribute arguments that are paths or identifiers without any specific value, like #[attr(std::io::Error, crate, super::SomeType)].

NB: All named arguments without the value assigned are getting into this field by default, even if they do not represent any known rust path or type name, like #[attr(some_id, other)]. However, with ParametrizedAttr::check and ParametrizedAttr::checked those values matching ones specified in AttrReq::arg_req with values set to crate::ListReq::Predefined::default are moved into ParametrizedAttr::args.

string: Option<LitStr>

Unnamed string literal found within attribute arguments.

If multiple string literals are present they are concatenated into a single value, like it is done by the rust compiler for #[doc = "..."] attributes

bytes: Option<LitByteStr>

Unnamed byte string literal found within attribute arguments.

If multiple byte string literals are present they are concatenated into a single value, like it is done by the rust compiler for #[doc = "..."] attributes

chars: Vec<LitChar>

Unnamed char literals found within attribute arguments

integers: Vec<LitInt>

Unnamed integer literals found within attribute arguments

floats: Vec<LitFloat>

Unnamed float literals found within attribute arguments

bool: Option<LitBool>

Unnamed bool literal found within attribute arguments.

If multiple bool literals are present this will generate an error.

Implementations

impl ParametrizedAttr

pub fn new(name: impl ToString) -> Self

Constructs named SingularAttr with empty internal data

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

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

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

Constructs ParametrizedAttr from a given syn::Attribute

pub fn arg_literal_value(&self, name: &str) -> Result<Lit, Error>

Returns literal value for a given argument with name name, if it is defined, or fails with Error::ArgValueRequired. See ArgValue::literal_value for the details.

pub fn has_verbatim(&self, verbatim: &str) -> bool

Checks if the attribute has a verbatim argument matching the provided verbatim string.

Verbatim arguments are arguments in form of #[attr(verbatim1, verbatim2], i.e. path arguments containing single path segment and no value or nested arguments.

pub fn verbatim(&self) -> HashSet<String>

Returns set of verbatim attribute arguments.

Verbatim arguments are arguments in form of #[attr(verbatim1, verbatim2], i.e. path arguments containing single path segment and no value or nested arguments.

pub fn merge(&mut self, other: Self) -> Result<(), Error>

Merges data from the other into the self.

Errors

• Fails with Error::NamesDontMatch if the names of the self and the other do not match
• Fails with Error::MultipleLiteralValues if both self and the other has a literals which values are not equal.

pub fn merged(self, other: Self) -> Result<Self, Error>

Does merging as in ParametrizedAttr::merge, but unlike it consumes the self and returns a merged structure in case of the successful operation. Useful in operation chains.

pub fn enrich(&mut self, attr: &Attribute) -> Result<(), Error>

Enriches current attribute data by adding information from the provided syn::Attribute.

Errors

• Fails with Error::NamesDontMatch if the names of the self and the provided attribute do not match
• Fails with Error::MultipleLiteralValues if both self and the provided attribute has a literals which values are not equal.

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

Performs enrich operation as in ParametrizedAttr::enrich, but unlike it consumes the self and returns an enriched structure in case of the successful operation. Useful in operation chains.

pub fn fuse(&mut self, attr: &Attribute) -> Result<(), Error>

Fuses data from a nested attribute arguments (see Attribute) into the attribute parameters.

The operation is similar to the ParametrizedAttr::enrich with the only difference that enrichment operation takes the whole attribute, and fusion takes a nested meta data.

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

Performs enrich operation as in ParametrizedAttr::fuse, but unlike it consumes the self and returns an enriched structure in case of the successful operation. Useful in operation chains.

pub fn check(&mut self, req: AttrReq) -> Result<(), Error>

Checks that the structure meets provided value requirements (see AttrReq), generating Error if the requirements are not met.

The procedure modifies the ParametrizedAttr data in the following ways:

1. First, it fills in ParametrizedAttr::paths, ParametrizedAttr::integers, ParametrizedAttr::floats, ParametrizedAttr::chars, ParametrizedAttr::bytes, ParametrizedAttr::string with default values from AttrReq::path_req, AttrReq::integer_req, AttrReq::float_req, AttrReq::char_req, AttrReq::bytes_req, AttrReq::string_req correspondingly.
2. ParametrizedAttr::paths values matching ones specified in AttrReq::arg_req with values set to crate::ListReq::Predefined::default are moved into ParametrizedAttr::args field.

pub fn checked(self, req: AttrReq) -> Result<Self, Error>

Performs check as in ParametrizedAttr::check, but unlike it consumes the self and returns a itself in case of the successful operation. Useful in operation chains.

Trait Implementations

impl Clone for ParametrizedAttr

fn clone(&self) -> ParametrizedAttr

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for ParametrizedAttr

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

Formats the value using the given formatter.