derive_more/
into_iterator.rs

1use crate::utils::{
2    add_extra_generic_param, add_extra_ty_param_bound_ref, SingleFieldData, State,
3};
4use proc_macro2::TokenStream;
5use quote::{quote, ToTokens};
6use syn::{parse::Result, DeriveInput};
7
8/// Provides the hook to expand `#[derive(IntoIterator)]` into an implementation of `IntoIterator`
9pub fn expand(input: &DeriveInput, trait_name: &'static str) -> Result<TokenStream> {
10    let state = State::with_field_ignore_and_refs(
11        input,
12        trait_name,
13        quote!(::core::iter),
14        String::from("into_iterator"),
15    )?;
16    let SingleFieldData {
17        input_type,
18        info,
19        field_type,
20        member,
21        trait_path,
22        ..
23    } = state.assert_single_enabled_field();
24
25    let mut tokens = TokenStream::new();
26
27    for ref_type in info.ref_types() {
28        let reference = ref_type.reference();
29        let lifetime = ref_type.lifetime();
30        let reference_with_lifetime = ref_type.reference_with_lifetime();
31
32        let generics_impl;
33        let generics =
34            add_extra_ty_param_bound_ref(&input.generics, trait_path, ref_type);
35        let (_, ty_generics, where_clause) = generics.split_for_impl();
36        let (impl_generics, _, _) = if ref_type.is_ref() {
37            generics_impl = add_extra_generic_param(&generics, lifetime.clone());
38            generics_impl.split_for_impl()
39        } else {
40            generics.split_for_impl()
41        };
42        // let generics = add_extra_ty_param_bound(&input.generics, trait_path);
43        let casted_trait =
44            &quote!(<#reference_with_lifetime #field_type as #trait_path>);
45        let into_iterator = quote! {
46            impl#impl_generics #trait_path for #reference_with_lifetime #input_type#ty_generics #where_clause
47            {
48                type Item = #casted_trait::Item;
49                type IntoIter = #casted_trait::IntoIter;
50                #[inline]
51                fn into_iter(self) -> Self::IntoIter {
52                    #casted_trait::into_iter(#reference #member)
53                }
54            }
55        };
56        into_iterator.to_tokens(&mut tokens);
57    }
58    Ok(tokens)
59}
derive_more/into_iterator.rs

derive_more/
into_iterator.rs
