1 files changed, 79 insertions, 0 deletions
diff --git a/src/related.rs b/src/related.rs
new file mode 100644
index 0000000..9b7f9e1
--- /dev/null
+++ b/src/related.rs
@@ -0,0 +1,79 @@
+use proc_macro2::TokenStream;
+use quote::{format_ident, quote};
+use syn::spanned::Spanned;
+
+use crate::{
+    diagnostic::{DiagnosticConcreteArgs, DiagnosticDef},
+    forward::WhichFn,
+    utils::{display_pat_members, gen_all_variants_with},
+};
+
+pub struct Related(syn::Member);
+
+impl Related {
+    pub(crate) fn from_fields(fields: &syn::Fields) -> syn::Result<Option<Self>> {
+        match fields {
+            syn::Fields::Named(named) => Self::from_fields_vec(named.named.iter().collect()),
+            syn::Fields::Unnamed(unnamed) => {
+                Self::from_fields_vec(unnamed.unnamed.iter().collect())
+            }
+            syn::Fields::Unit => Ok(None),
+        }
+    }
+
+    fn from_fields_vec(fields: Vec<&syn::Field>) -> syn::Result<Option<Self>> {
+        for (i, field) in fields.iter().enumerate() {
+            for attr in &field.attrs {
+                if attr.path().is_ident("related") {
+                    let related = if let Some(ident) = field.ident.clone() {
+                        syn::Member::Named(ident)
+                    } else {
+                        syn::Member::Unnamed(syn::Index {
+                            index: i as u32,
+                            span: field.span(),
+                        })
+                    };
+                    return Ok(Some(Related(related)));
+                }
+            }
+        }
+        Ok(None)
+    }
+
+    pub(crate) fn gen_enum(variants: &[DiagnosticDef]) -> Option<TokenStream> {
+        gen_all_variants_with(
+            variants,
+            WhichFn::Related,
+            |ident, fields, DiagnosticConcreteArgs { related, .. }| {
+                let (display_pat, _display_members) = display_pat_members(fields);
+                related.as_ref().map(|related| {
+                    let rel = match &related.0 {
+                        syn::Member::Named(ident) => ident.clone(),
+                        syn::Member::Unnamed(syn::Index { index, .. }) => {
+                            format_ident!("_{}", index)
+                        }
+                    };
+                    quote! {
+                        Self::#ident #display_pat => {
+                            std::option::Option::Some(std::boxed::Box::new(
+                                #rel.iter().map(|x| -> &(dyn miette::Diagnostic) { &*x })
+                            ))
+                        }
+                    }
+                })
+            },
+        )
+    }
+
+    pub(crate) fn gen_struct(&self) -> Option<TokenStream> {
+        let rel = &self.0;
+        Some(quote! {
+            fn related<'a>(&'a self) -> std::option::Option<std::boxed::Box<dyn std::iter::Iterator<Item = &'a dyn miette::Diagnostic> + 'a>> {
+                use ::core::borrow::Borrow;
+                std::option::Option::Some(std::boxed::Box::new(
+                        self.#rel.iter().map(|x| -> &(dyn miette::Diagnostic) { &*x.borrow() })
+                ))
+            }
+        })
+    }
+}