darling_core/options/
from_meta.rs

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1use proc_macro2::TokenStream;
2use quote::ToTokens;
3
4use crate::ast::Data;
5use crate::codegen::FromMetaImpl;
6use crate::error::Accumulator;
7use crate::options::{Core, ParseAttribute, ParseData};
8use crate::{Error, Result};
9
10pub struct FromMetaOptions {
11    base: Core,
12}
13
14impl FromMetaOptions {
15    pub fn new(di: &syn::DeriveInput) -> Result<Self> {
16        (FromMetaOptions {
17            base: Core::start(di)?,
18        })
19        .parse_attributes(&di.attrs)?
20        .parse_body(&di.data)
21    }
22}
23
24impl ParseAttribute for FromMetaOptions {
25    fn parse_nested(&mut self, mi: &syn::Meta) -> Result<()> {
26        self.base.parse_nested(mi)
27    }
28}
29
30impl ParseData for FromMetaOptions {
31    fn parse_variant(&mut self, variant: &syn::Variant) -> Result<()> {
32        self.base.parse_variant(variant)
33    }
34
35    fn parse_field(&mut self, field: &syn::Field) -> Result<()> {
36        self.base.parse_field(field)
37    }
38
39    fn validate_body(&self, errors: &mut Accumulator) {
40        self.base.validate_body(errors);
41
42        if let Data::Enum(ref data) = self.base.data {
43            // Adds errors for duplicate `#[darling(word)]` annotations across all variants.
44            let word_variants: Vec<_> = data
45                .iter()
46                .filter_map(|variant| variant.word.as_ref())
47                .collect();
48            if word_variants.len() > 1 {
49                for word in word_variants {
50                    errors.push(
51                        Error::custom("`#[darling(word)]` can only be applied to one variant")
52                            .with_span(&word.span()),
53                    );
54                }
55            }
56        }
57    }
58}
59
60impl<'a> From<&'a FromMetaOptions> for FromMetaImpl<'a> {
61    fn from(v: &'a FromMetaOptions) -> Self {
62        FromMetaImpl {
63            base: (&v.base).into(),
64        }
65    }
66}
67
68impl ToTokens for FromMetaOptions {
69    fn to_tokens(&self, tokens: &mut TokenStream) {
70        FromMetaImpl::from(self).to_tokens(tokens)
71    }
72}
darling_core/options/from_meta.rs

darling_core/options/
from_meta.rs
