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use darling::FromDeriveInput;
use proc_macro::TokenStream;
use proc_macro2::TokenStream as TokenStream2;
use quote::ToTokens;
use std::iter::Iterator;
use syn::{parse_quote, Error, Generics, Path, TypeGenerics};
/// Merge multiple [`syn::Error`] into one.
pub(crate) trait IteratorExt {
fn collect_error(self) -> Result<(), Error>
where
Self: Iterator<Item = Result<(), Error>> + Sized,
{
let accu = Ok(());
self.fold(accu, |accu, error| match (accu, error) {
(Ok(()), error) => error,
(accu, Ok(())) => accu,
(Err(mut err), Err(error)) => {
err.combine(error);
Err(err)
}
})
}
}
impl<I> IteratorExt for I where I: Iterator<Item = Result<(), Error>> + Sized {}
/// Attributes usable for derive macros
#[derive(FromDeriveInput, Debug)]
#[darling(attributes(serde_with))]
pub(crate) struct DeriveOptions {
/// Path to the crate
#[darling(rename = "crate", default)]
pub(crate) alt_crate_path: Option<Path>,
}
impl DeriveOptions {
pub(crate) fn from_derive_input(input: &syn::DeriveInput) -> Result<Self, TokenStream> {
match <Self as FromDeriveInput>::from_derive_input(input) {
Ok(v) => Ok(v),
Err(e) => Err(TokenStream::from(e.write_errors())),
}
}
pub(crate) fn get_serde_with_path(&self) -> Path {
self.alt_crate_path
.clone()
.unwrap_or_else(|| syn::parse_str("::serde_with").unwrap())
}
}
// Inspired by https://github.com/serde-rs/serde/blob/fb2fe409c8f7ad6c95e3096e5e9ede865c8cfb49/serde_derive/src/de.rs#L3120
// Serde is also licences Apache 2 + MIT
pub(crate) fn split_with_de_lifetime(
generics: &Generics,
) -> (
DeImplGenerics<'_>,
TypeGenerics<'_>,
Option<&syn::WhereClause>,
) {
let de_impl_generics = DeImplGenerics(generics);
let (_, ty_generics, where_clause) = generics.split_for_impl();
(de_impl_generics, ty_generics, where_clause)
}
pub(crate) struct DeImplGenerics<'a>(&'a Generics);
impl<'a> ToTokens for DeImplGenerics<'a> {
fn to_tokens(&self, tokens: &mut TokenStream2) {
let mut generics = self.0.clone();
generics.params = Some(parse_quote!('de))
.into_iter()
.chain(generics.params)
.collect();
let (impl_generics, _, _) = generics.split_for_impl();
impl_generics.to_tokens(tokens);
}
}
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