1use proc_macro2;
2
3use ast;
4use attr;
5use bound;
6use syn;
7
8/// Make generic with all the generics in the input, plus a bound `T: <trait_path>` for each
9/// generic field type that will be shown.
10pub fn build_impl_generics<F, G, H>(
11 item: &ast::Input,
12 trait_path: &syn::Path,
13 needs_debug_bound: F,
14 field_bound: G,
15 input_bound: H,
16) -> syn::Generics
17where
18 F: Fn(&attr::Field) -> bool,
19 G: Fn(&attr::Field) -> Option<&[syn::WherePredicate]>,
20 H: Fn(&attr::Input) -> Option<&[syn::WherePredicate]>,
21{
22 let generics: Generics = bound::without_defaults(item.generics);
23 let generics: Generics = bound::with_where_predicates_from_fields(item, &generics, from_field:field_bound);
24
25 match input_bound(&item.attrs) {
26 Some(predicates: &[WherePredicate]) => bound::with_where_predicates(&generics, predicates),
27 None => bound::with_bound(item, &generics, filter:needs_debug_bound, bound:trait_path),
28 }
29}
30
31/// Construct a name for the inner type parameter that can't collide with any
32/// type parameters of the item. This is achieved by starting with a base and
33/// then concatenating the names of all other type parameters.
34pub fn hygienic_type_parameter(item: &ast::Input, base: &str) -> syn::Ident {
35 let mut typaram: String = String::with_capacity(150);
36 typaram.push_str(string:base);
37 let typaram: String = item.generics.type_params().fold(init:typaram, |mut acc: String, ty: &TypeParam| {
38 acc.push_str(&format!("{}", &ty.ident));
39 acc
40 });
41
42 syn::Ident::new(&typaram, proc_macro2::Span::call_site())
43}
44