51 lines
1.7 KiB
Rust
51 lines
1.7 KiB
Rust
use darling::{util::parse_expr, FromDeriveInput, FromMeta};
|
|
use syn::{parse_quote, Expr};
|
|
|
|
#[derive(FromDeriveInput)]
|
|
#[darling(attributes(demo))]
|
|
pub struct Receiver {
|
|
#[darling(with = parse_expr::preserve_str_literal, map = Some)]
|
|
example1: Option<Expr>,
|
|
#[darling(
|
|
with = |m| Ok(String::from_meta(m)?.to_uppercase()),
|
|
map = Some
|
|
)]
|
|
example2: Option<String>,
|
|
// This is deliberately strange - it keeps the field name, and ignores
|
|
// the rest of the attribute. In normal operation, this is strongly discouraged.
|
|
// It's used here to verify that the parameter type is known even if it can't be
|
|
// inferred from usage within the closure.
|
|
#[darling(with = |m| Ok(m.path().clone()))]
|
|
example3: syn::Path,
|
|
#[darling(with = "example4_parser")]
|
|
example4: String,
|
|
}
|
|
|
|
// the custom parser function referred to by string
|
|
fn example4_parser(meta: &syn::Meta) -> darling::Result<String> {
|
|
match meta {
|
|
syn::Meta::NameValue(nv) => match &nv.value {
|
|
syn::Expr::Lit(syn::ExprLit {
|
|
lit: syn::Lit::Str(s),
|
|
..
|
|
}) => Ok(s.value()),
|
|
other => Err(darling::Error::unexpected_expr_type(other)),
|
|
},
|
|
_ => Err(darling::Error::unexpected_type("name-value")),
|
|
}
|
|
}
|
|
|
|
#[test]
|
|
fn handles_all_cases() {
|
|
let input = Receiver::from_derive_input(&parse_quote! {
|
|
#[demo(example1 = test::path, example2 = "hello", example3, example4 = "world")]
|
|
struct Example;
|
|
})
|
|
.unwrap();
|
|
|
|
assert_eq!(input.example1, Some(parse_quote!(test::path)));
|
|
assert_eq!(input.example2, Some("HELLO".to_string()));
|
|
assert_eq!(input.example3, parse_quote!(example3));
|
|
assert_eq!(input.example4, "world".to_string());
|
|
}
|