darling_core/options/
forward_attrs.rs

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1use proc_macro2::Ident;
2use syn::Path;
3
4use crate::ast::NestedMeta;
5use crate::util::PathList;
6use crate::{Error, FromField, FromMeta, Result};
7
8use super::ParseAttribute;
9
10/// The `attrs` magic field and attributes that influence its behavior.
11#[derive(Debug, Clone)]
12pub struct AttrsField {
13    /// The ident of the field that will receive the forwarded attributes.
14    pub ident: Ident,
15    /// Path of the function that will be called to convert the `Vec` of
16    /// forwarded attributes into the type expected by the field in `ident`.
17    pub with: Option<Path>,
18}
19
20impl FromField for AttrsField {
21    fn from_field(field: &syn::Field) -> crate::Result<Self> {
22        let result = Self {
23            ident: field.ident.clone().ok_or_else(|| {
24                Error::custom("attributes receiver must be named field").with_span(field)
25            })?,
26            with: None,
27        };
28
29        result.parse_attributes(&field.attrs)
30    }
31}
32
33impl ParseAttribute for AttrsField {
34    fn parse_nested(&mut self, mi: &syn::Meta) -> crate::Result<()> {
35        if mi.path().is_ident("with") {
36            if self.with.is_some() {
37                return Err(Error::duplicate_field_path(mi.path()).with_span(mi));
38            }
39
40            self.with = FromMeta::from_meta(mi)?;
41            Ok(())
42        } else {
43            Err(Error::unknown_field_path_with_alts(mi.path(), &["with"]).with_span(mi))
44        }
45    }
46}
47
48/// A rule about which attributes to forward to the generated struct.
49#[derive(Debug, Clone, PartialEq, Eq)]
50pub enum ForwardAttrsFilter {
51    All,
52    Only(PathList),
53}
54
55impl ForwardAttrsFilter {
56    /// Returns `true` if this will not forward any attributes.
57    pub fn is_empty(&self) -> bool {
58        match *self {
59            ForwardAttrsFilter::All => false,
60            ForwardAttrsFilter::Only(ref list) => list.is_empty(),
61        }
62    }
63}
64
65impl FromMeta for ForwardAttrsFilter {
66    fn from_word() -> Result<Self> {
67        Ok(ForwardAttrsFilter::All)
68    }
69
70    fn from_list(nested: &[NestedMeta]) -> Result<Self> {
71        Ok(ForwardAttrsFilter::Only(PathList::from_list(nested)?))
72    }
73}
darling_core/options/forward_attrs.rs

darling_core/options/
forward_attrs.rs
