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use crate::utils::{
add_extra_generic_param, add_extra_ty_param_bound_ref, SingleFieldData, State,
};
use proc_macro2::TokenStream;
use quote::{quote, ToTokens};
use syn::{parse::Result, DeriveInput};
/// Provides the hook to expand `#[derive(IntoIterator)]` into an implementation of `IntoIterator`
pub fn expand(input: &DeriveInput, trait_name: &'static str) -> Result<TokenStream> {
let state =
State::with_field_ignore_and_refs(input, trait_name, "into_iterator".into())?;
let SingleFieldData {
input_type,
info,
field_type,
member,
trait_path,
..
} = state.assert_single_enabled_field();
let mut tokens = TokenStream::new();
for ref_type in info.ref_types() {
let reference = ref_type.reference();
let lifetime = ref_type.lifetime();
let reference_with_lifetime = ref_type.reference_with_lifetime();
let generics_impl;
let generics =
add_extra_ty_param_bound_ref(&input.generics, trait_path, ref_type);
let (_, ty_generics, where_clause) = generics.split_for_impl();
let (impl_generics, _, _) = if ref_type.is_ref() {
generics_impl = add_extra_generic_param(&generics, lifetime.clone());
generics_impl.split_for_impl()
} else {
generics.split_for_impl()
};
// let generics = add_extra_ty_param_bound(&input.generics, trait_path);
let casted_trait = "e! {
<#reference_with_lifetime #field_type as #trait_path>
};
let into_iterator = quote! {
#[automatically_derived]
impl #impl_generics #trait_path for #reference_with_lifetime #input_type #ty_generics
#where_clause
{
type Item = #casted_trait::Item;
type IntoIter = #casted_trait::IntoIter;
#[inline]
fn into_iter(self) -> Self::IntoIter {
#casted_trait::into_iter(#reference #member)
}
}
};
into_iterator.to_tokens(&mut tokens);
}
Ok(tokens)
}
|
