educe/trait_handlers/deref_mut/models/
field_attribute.rs

1use proc_macro2::Span;
2use syn::{punctuated::Punctuated, spanned::Spanned, Attribute, Meta, Token};
3
4use crate::{panic, supported_traits::Trait};
5
6pub(crate) struct FieldAttribute {
7    pub(crate) flag: bool,
8    pub(crate) span: Span,
9}
10
11pub(crate) struct FieldAttributeBuilder {
12    pub(crate) enable_flag: bool,
13}
14
15impl FieldAttributeBuilder {
16    pub(crate) fn build_from_deref_mut_meta(&self, meta: &Meta) -> syn::Result<FieldAttribute> {
17        debug_assert!(meta.path().is_ident("DerefMut"));
18
19        let correct_usage_for_deref_mut_attribute = {
20            let mut usage = vec![];
21
22            if self.enable_flag {
23                usage.push(stringify!(#[educe(DerefMut)]));
24            }
25
26            usage
27        };
28
29        match meta {
30            Meta::Path(_) => {
31                if !self.enable_flag {
32                    return Err(panic::attribute_incorrect_format(
33                        meta.path().get_ident().unwrap(),
34                        &correct_usage_for_deref_mut_attribute,
35                    ));
36                }
37            },
38            Meta::NameValue(_) | Meta::List(_) => {
39                return Err(panic::attribute_incorrect_format(
40                    meta.path().get_ident().unwrap(),
41                    &correct_usage_for_deref_mut_attribute,
42                ));
43            },
44        }
45
46        Ok(FieldAttribute {
47            flag: true, span: meta.span()
48        })
49    }
50
51    pub(crate) fn build_from_attributes(
52        &self,
53        attributes: &[Attribute],
54        traits: &[Trait],
55    ) -> syn::Result<FieldAttribute> {
56        let mut output = None;
57
58        for attribute in attributes.iter() {
59            let path = attribute.path();
60
61            if path.is_ident("educe") {
62                if let Meta::List(list) = &attribute.meta {
63                    let result =
64                        list.parse_args_with(Punctuated::<Meta, Token![,]>::parse_terminated)?;
65
66                    for meta in result {
67                        let path = meta.path();
68
69                        let t = match Trait::from_path(path) {
70                            Some(t) => t,
71                            None => return Err(panic::unsupported_trait(meta.path())),
72                        };
73
74                        if !traits.contains(&t) {
75                            return Err(panic::trait_not_used(path.get_ident().unwrap()));
76                        }
77
78                        if t == Trait::DerefMut {
79                            if output.is_some() {
80                                return Err(panic::reuse_a_trait(path.get_ident().unwrap()));
81                            }
82
83                            output = Some(self.build_from_deref_mut_meta(&meta)?);
84                        }
85                    }
86                }
87            }
88        }
89
90        Ok(output.unwrap_or(FieldAttribute {
91            flag: false, span: Span::call_site()
92        }))
93    }
94}
educe/trait_handlers/deref_mut/models/field_attribute.rs

educe/trait_handlers/deref_mut/models/
field_attribute.rs
