5 unstable releases
0.3.0 | Feb 3, 2023 |
---|---|
0.2.2 | Feb 3, 2023 |
0.2.1 | Feb 3, 2023 |
0.2.0 | Feb 3, 2023 |
0.1.0 | Feb 3, 2023 |
#24 in #procmacro
27 downloads per month
Used in syner
33KB
661 lines
Syner - A simple, fast and safe way to parse attributes from syn
Syner is a simple, fast and safe way to parse attributes from syn. It is designed to be used with the syn crate.
Definition of your attributes is done using a procedural macro. This allows you to define your attributes in a type safe way.
You create a struct that represents your attribute and then use the #[derive(Syner)]
macro to generate the parsing code.
Example
#[derive(Syner)]
struct Test {
pub some: String,
pub maybe: Option<String>,
#[syner(default)]
pub is_default: bool,
pub inner: Inner,
pub inner_list: Vec<Inner>,
pub inner_bools: Vec<bool>,
pub inner_maybe: Option<Inner>,
}
#[derive(Syner, PartialEq, Debug)]
struct Inner {
pub some: String,
pub is_default: bool,
}
This will parse the following attribute:
#[test(
some = "hello",
inner(
some = "inner",
is_default = true
),
inner_list(
inner(
some = "inner_list0",
is_default = true
),
inner(
some = "inner_list1",
is_default = false
),
inner(
some = "inner_list2",
is_default = true
)
),
inner_bools(true, false, true)
)]
struct TestStruct {}
You can parse the attribute using the parse_attrs
function.
It takes an iterator of syn::Attribute
and returns a Result
with the parsed attribute.
let attrs = Test::parse_attrs(&item.attrs)?;
Supported types
Syner supports the following types:
String
- Parses the value as a stringbool
- Parses the value as a booleani8
,i16
,i32
,i64
,i128
,isize
- Parses the value as a signed integeru8
,u16
,u32
,u64
,u128
,usize
- Parses the value as an unsigned integerf32
,f64
- Parses the value as a floatT
- Parses the value as<name>(T)
ifT
is a struct that implementsSyner
Option<T>
- Parses the value asT
if it is presentVec<T>
- Parses the value as<name>(T...)
Annotating a field with #[syner(default)]
will make it optional and use the default value if it is not present.
You can also use #[syner(default = "<expr>")]
to specify a default value.
The name of the field is used as the name of the attribute except if the field is of type Vec<T>
,
in which case the name of the struct (lowercase
) is used.
For the top level attribute the lowercase name of the struct is used as a default name.
If you want to use a different name you can annotate the struct with #[syner(name = "<name>")]
.
License
This project is licensed under the MIT License - see the LICENSE file for details
Dependencies
~1.5MB
~37K SLoC