darling_core/
macros_public.rs

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1//! Macros that should be exported from both `darling_core` and `darling`.
2//! Note that these are **sym-linked** into the main code, and so cannot declare on items that are exported differently
3//! in `darling_core` vs. `darling`.
4
5/// Generator for `UsesTypeParam` impls that unions the used type parameters of the selected fields.
6///
7/// # Usage
8/// The macro takes the type implementing the trait as the first argument, then a comma-separated list of
9/// fields for the rest of its arguments.
10///
11/// The type of each passed-in field must implement `UsesTypeParams`, or the resulting code won't compile.
12///
13/// ```rust
14/// # extern crate syn;
15/// # use darling_core::uses_type_params;
16/// #
17/// struct MyField {
18///     ty: syn::Type,
19/// }
20///
21/// uses_type_params!(MyField, ty);
22///
23/// fn main() {
24///     // no test run
25/// }
26/// ```
27///
28/// `darling` cannot derive this trait automatically, as it doesn't know which information extracted from
29/// proc-macro input is meant to constitute "using" the type parameter, but crate consumers should
30/// implement it by hand or using the macro.
31#[macro_export]
32macro_rules! uses_type_params {
33    ($impl_type:ty, $accessor:ident) => {
34        impl $crate::usage::UsesTypeParams for $impl_type {
35            fn uses_type_params<'gen>(
36                &self,
37                options: &$crate::usage::Options,
38                type_set: &'gen $crate::usage::IdentSet
39            ) -> $crate::usage::IdentRefSet<'gen> {
40                self.$accessor.uses_type_params(options, type_set)
41            }
42        }
43    };
44    ($impl_type:ty, $first:ident, $($field:ident),+) => {
45        impl $crate::usage::UsesTypeParams for $impl_type {
46            fn uses_type_params<'gen>(
47                &self,
48                options: &$crate::usage::Options,
49                type_set: &'gen $crate::usage::IdentSet
50            ) -> $crate::usage::IdentRefSet<'gen> {
51                let mut hits = self.$first.uses_type_params(options, type_set);
52                $(
53                    hits.extend(self.$field.uses_type_params(options, type_set));
54                )*
55                hits
56            }
57        }
58    };
59}
60
61/// Generator for `UsesLifetimes` impls that unions the used lifetimes of the selected fields.
62///
63/// # Usage
64/// The macro takes the type implementing the trait as the first argument, then a comma-separated list of
65/// fields for the rest of its arguments.
66///
67/// The type of each passed-in field must implement `UsesLifetimes`, or the resulting code won't compile.
68#[macro_export]
69macro_rules! uses_lifetimes {
70    ($impl_type:ty, $accessor:ident) => {
71        impl $crate::usage::UsesLifetimes for $impl_type {
72            fn uses_lifetimes<'gen>(
73                &self,
74                options: &$crate::usage::Options,
75                type_set: &'gen $crate::usage::LifetimeSet
76            ) -> $crate::usage::LifetimeRefSet<'gen> {
77                self.$accessor.uses_lifetimes(options, type_set)
78            }
79        }
80    };
81    ($impl_type:ty, $first:ident, $($field:ident),+) => {
82        impl $crate::usage::UsesLifetimes for $impl_type {
83            fn uses_lifetimes<'gen>(
84                &self,
85                options: &$crate::usage::Options,
86                type_set: &'gen $crate::usage::LifetimeSet
87            ) -> $crate::usage::LifetimeRefSet<'gen> {
88                let mut hits = self.$first.uses_lifetimes(options, type_set);
89                $(
90                    hits.extend(self.$field.uses_lifetimes(options, type_set));
91                )*
92                hits
93            }
94        }
95    };
96}
darling_core/macros_public.rs

darling_core/
macros_public.rs
