darling 0.3.0

A proc-macro library for reading attributes into structs when implementing custom derives.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70

#[macro_use]
extern crate darling;

#[macro_use]
extern crate syn;
#[macro_use]
extern crate quote;

use darling::FromDeriveInput;

#[derive(Default, FromMetaItem, PartialEq, Debug)]
#[darling(default)]
struct Lorem {
    ipsum: bool,
    dolor: Option<String>,
}

#[derive(FromDeriveInput, PartialEq, Debug)]
#[darling(attributes(darling_demo))]
struct Core {
    ident: syn::Ident,
    vis: syn::Visibility,
    generics: syn::Generics,
    lorem: Lorem
}

#[derive(FromDeriveInput, PartialEq, Debug)]
#[darling(attributes(darling_demo))]
struct TraitCore {
    ident: syn::Ident,
    generics: syn::Generics,
    lorem: Lorem,
}

#[test]
fn simple() {
    let di = syn::parse_str(r#"
        #[derive(Foo)]
        #[darling_demo(lorem(ipsum))]
        pub struct Bar;
    "#).unwrap();

    assert_eq!(Core::from_derive_input(&di).unwrap(), Core {
        ident: syn::Ident::from("Bar"),
        vis: parse_quote!(pub),
        generics: Default::default(),
        lorem: Lorem {
            ipsum: true,
            dolor: None,
        }
    });
}

#[test]
fn trait_type() {
    let di = syn::parse_str(r#"
        #[derive(Foo)]
        #[darling_demo(lorem(dolor = "hello"))]
        pub struct Bar;
    "#).unwrap();

    assert_eq!(TraitCore::from_derive_input(&di).unwrap(), TraitCore {
        ident: syn::Ident::from("Bar"),
        generics: Default::default(),
        lorem: Lorem {
            ipsum: false,
            dolor: Some("hello".to_owned()),
        }
    });
}