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use proc_macro_error::{abort, proc_macro_error};
use quote::quote;
use quote::ToTokens;
use syn::spanned::Spanned;
mod captures;
mod impl_enum;
mod impl_struct;
#[proc_macro_error]
#[proc_macro_derive(FromRegex, attributes(from_regex))]
pub fn derive_regex(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
let input = syn::parse_macro_input!(input as syn::DeriveInput);
Item::from(&input).into_token_stream().into()
}
#[proc_macro_error]
#[proc_macro_derive(FromStr, attributes(from_regex))]
pub fn derive_str(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
let input = syn::parse_macro_input!(input as syn::DeriveInput);
let ident = input.ident.clone();
let item = Item::from(&input);
let stream = quote! {
#item
impl std::str::FromStr for #ident {
type Err = ();
fn from_str(s: &str) -> Result<Self, Self::Err> {
Self::from_regex(s).ok_or(())
}
}
};
stream.into()
}
const ATTRIBUTE: &str = "from_regex";
enum Item<'a> {
Enum(impl_enum::Item<'a>),
Struct(impl_struct::Item<'a>),
}
impl<'a> From<&'a syn::DeriveInput> for Item<'a> {
fn from(input: &'a syn::DeriveInput) -> Self {
let syn::DeriveInput {
data, attrs, ident, ..
} = input;
match data {
syn::Data::Enum(data_enum) => Item::Enum(impl_enum::Item::new(
ident,
&attrs,
data_enum.variants.iter(),
)),
syn::Data::Struct(syn::DataStruct { fields, .. }) => {
Item::Struct(impl_struct::Item::new(ident, &attrs, &fields))
}
syn::Data::Union(syn::DataUnion { union_token, .. }) => {
abort!(union_token.span(), "Unsupported item type")
}
}
}
}
impl<'a> ToTokens for Item<'a> {
fn to_tokens(&self, tokens: &mut proc_macro2::TokenStream) {
match self {
Item::Enum(item) => item.to_tokens(tokens),
Item::Struct(item) => item.to_tokens(tokens),
}
}
}
struct Attributes<'a> {
iter: core::slice::Iter<'a, syn::Attribute>,
list: Option<syn::punctuated::IntoIter<syn::NestedMeta>>,
}
impl<'a> From<&'a [syn::Attribute]> for Attributes<'a> {
fn from(attrs: &'a [syn::Attribute]) -> Self {
Self {
iter: attrs.iter(),
list: None,
}
}
}
impl<'a> Iterator for Attributes<'a> {
type Item = syn::NestedMeta;
fn next(&mut self) -> Option<Self::Item> {
if let Some(list) = &mut self.list {
if let Some(nested) = list.next() {
return Some(nested);
}
}
loop {
let next = self.iter.next()?;
if let syn::Meta::List(list) = next.parse_meta().expect("failed to parse attr meta") {
if list.path.is_ident(ATTRIBUTE) {
let mut list = list.nested.into_iter();
if let Some(next) = list.next() {
self.list = Some(list);
return Some(next);
}
}
}
}
}
}