miette_derive/
diagnostic_source.rs

1use proc_macro2::TokenStream;
2use quote::quote;
3use syn::spanned::Spanned;
4
5use crate::forward::WhichFn;
6use crate::{
7    diagnostic::{DiagnosticConcreteArgs, DiagnosticDef},
8    utils::{display_pat_members, gen_all_variants_with},
9};
10
11pub struct DiagnosticSource(syn::Member);
12
13impl DiagnosticSource {
14    pub(crate) fn from_fields(fields: &syn::Fields) -> syn::Result<Option<Self>> {
15        match fields {
16            syn::Fields::Named(named) => Self::from_fields_vec(named.named.iter().collect()),
17            syn::Fields::Unnamed(unnamed) => {
18                Self::from_fields_vec(unnamed.unnamed.iter().collect())
19            }
20            syn::Fields::Unit => Ok(None),
21        }
22    }
23
24    fn from_fields_vec(fields: Vec<&syn::Field>) -> syn::Result<Option<Self>> {
25        for (i, field) in fields.iter().enumerate() {
26            for attr in &field.attrs {
27                if attr.path().is_ident("diagnostic_source") {
28                    let diagnostic_source = if let Some(ident) = field.ident.clone() {
29                        syn::Member::Named(ident)
30                    } else {
31                        syn::Member::Unnamed(syn::Index {
32                            index: i as u32,
33                            span: field.span(),
34                        })
35                    };
36                    return Ok(Some(DiagnosticSource(diagnostic_source)));
37                }
38            }
39        }
40        Ok(None)
41    }
42
43    pub(crate) fn gen_enum(variants: &[DiagnosticDef]) -> Option<TokenStream> {
44        gen_all_variants_with(
45            variants,
46            WhichFn::DiagnosticSource,
47            |ident,
48             fields,
49             DiagnosticConcreteArgs {
50                 diagnostic_source, ..
51             }| {
52                let (display_pat, _display_members) = display_pat_members(fields);
53                diagnostic_source.as_ref().map(|diagnostic_source| {
54                    let rel = match &diagnostic_source.0 {
55                        syn::Member::Named(ident) => ident.clone(),
56                        syn::Member::Unnamed(syn::Index { index, .. }) => {
57                            quote::format_ident!("_{}", index)
58                        }
59                    };
60                    quote! {
61                        Self::#ident #display_pat => {
62                            std::option::Option::Some(std::borrow::Borrow::borrow(#rel))
63                        }
64                    }
65                })
66            },
67        )
68    }
69
70    pub(crate) fn gen_struct(&self) -> Option<TokenStream> {
71        let rel = &self.0;
72        Some(quote! {
73            fn diagnostic_source<'a>(&'a self) -> std::option::Option<&'a dyn miette::Diagnostic> {
74                std::option::Option::Some(std::borrow::Borrow::borrow(&self.#rel))
75            }
76        })
77    }
78}
miette_derive/diagnostic_source.rs

miette_derive/
diagnostic_source.rs
