[go: up one dir, main page]

derivative 0.3.0

A set of alternative `derive` attributes for Rust
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
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88

use ast;
use attr;
use bound;
use syn;

pub fn derivative_attribute(attr: &syn::Attribute) -> Option<&[syn::MetaItem]> {
    match attr.value {
        syn::MetaItem::List(ref name, ref mis) if name == "derivative" => {
            Some(mis)
        }
        syn::MetaItem::Word(..) |
        syn::MetaItem::NameValue(..) |
        syn::MetaItem::List(..) => None,
    }
}

pub fn remove_derivative_attrs(input: &mut syn::MacroInput) {
    fn remove_from_vec(attrs: &mut Vec<syn::Attribute>) {
        attrs.retain(|attr| derivative_attribute(attr).is_none());
    }

    fn remove_from_variant_data(vd: &mut syn::VariantData) {
        match *vd {
            syn::VariantData::Struct(ref mut fields) |
            syn::VariantData::Tuple(ref mut fields) => {
                for field in fields {
                    remove_from_vec(&mut field.attrs);
                }
            }
            syn::VariantData::Unit => (),
        }
    }

    remove_from_vec(&mut input.attrs);

    match input.body {
        syn::Body::Enum(ref mut variants) => {
            for variant in variants {
                remove_from_vec(&mut variant.attrs);
                remove_from_variant_data(&mut variant.data);
            }
        }
        syn::Body::Struct(ref mut vd) => {
            remove_from_variant_data(vd);
        }
    }
 }

/// Make generic with all the generics in the input, plus a bound `T: <trait_path>` for each
/// generic field type that will be shown.
pub fn build_impl_generics<F, G, H>(
    item: &ast::Input,
    trait_path: &syn::Path,
    needs_debug_bound: F,
    field_bound: G,
    input_bound: H,
) -> syn::Generics
    where F: Fn(&attr::Field) -> bool,
          G: Fn(&attr::Field) -> Option<&[syn::WherePredicate]>,
          H: Fn(&attr::Input) -> Option<&[syn::WherePredicate]>,
{
    let generics = bound::without_defaults(item.generics);
    let generics = bound::with_where_predicates_from_fields(
        item, &generics, field_bound
    );

    match input_bound(&item.attrs) {
        Some(predicates) => {
            bound::with_where_predicates(&generics, predicates)
        }
        None => {
            bound::with_bound(item, &generics, needs_debug_bound, trait_path)
        }
    }
}

/// Construct a name for the inner type parameter that can't collide with any
/// type parameters of the item. This is achieved by starting with a base and
/// then concatenating the names of all other type parameters.
pub fn hygienic_type_parameter(item: &ast::Input, base: &str) -> syn::Ident {
    let mut typaram = String::from(base);

    for ty in &item.generics.ty_params {
        typaram.push_str(&ty.ident.as_ref());
    }

    syn::Ident::new(typaram)
}