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use proc_macro::{self, TokenStream};
use proc_macro2::{Ident, Span};
use quote::quote;
use syn::{parse_macro_input, Attribute, DeriveInput, Lit, Meta, NestedMeta};
#[proc_macro_derive(UID, attributes(uid, alias))]
pub fn derive(input: TokenStream) -> TokenStream {
let input = parse_macro_input!(input as DeriveInput);
let ident: proc_macro2::Ident = input.ident;
let attrs: Vec<_> = input
.attrs
.into_iter()
.filter(|attr| attr.path.is_ident("uid") || attr.path.is_ident("alias"))
.collect();
let token = match attrs.len() {
n if n == 0 => Ok(quote! {
impl UniqueIdentifier for #ident {
type Data = Vec<f64>;
}
})
.map(|token| token.into()),
n if n == 1 => {
let attr = &attrs[0];
match attr.path.get_ident() {
Some(id) if id == "uid" => get_data_type(attr)
.map(|data| {
quote! {
impl UniqueIdentifier for #ident {
type Data = #data;
}
}
})
.map(|token| token.into()),
Some(id) if id == "alias" => {
get_name_client_traits(attr).and_then(|alias| alias.token(ident))
}
_ => Err(syn::Error::new_spanned(
attr,
"expected only a single attribute",
)),
}
}
_ => Err(syn::Error::new(
Span::mixed_site(),
"expected only a single input",
)),
};
match token {
Ok(token) => token,
Err(e) => e.into_compile_error().into(),
}
}
fn get_data_type(attr: &Attribute) -> syn::Result<syn::TypePath> {
let meta = attr.parse_meta()?;
match meta {
Meta::List(list) => {
if list.nested.len() == 1 {
let nested = &list.nested[0];
match nested {
NestedMeta::Meta(Meta::NameValue(nv)) => {
if nv.path.is_ident("data") {
if let Lit::Str(ref val) = nv.lit {
val.parse()
} else {
Err(syn::Error::new_spanned(&nv.lit, "expected String litteral"))
}
} else {
Err(syn::Error::new_spanned(
&nv.path,
"expected `data` as uid attribute",
))
}
}
_ => Err(syn::Error::new_spanned(
nested,
"expected `name = \"<value>\"` argument",
)),
}
} else {
Err(syn::Error::new_spanned(
list,
"expected only a single attribute",
))
}
}
_ => Err(syn::Error::new_spanned(
meta,
"expected a list of attributes",
)),
}
}
struct Alias {
name: syn::Result<syn::TypePath>,
client: Client,
}
struct Client {
name: syn::Result<syn::TypePath>,
traits: syn::Result<String>,
}
impl Alias {
fn token(self, ident: Ident) -> syn::Result<TokenStream> {
self.name
.and_then(|name| {
if let (Ok(client), Ok(traits)) = (self.client.name, self.client.traits) {
traits
.split(',')
.map(|t| match t.trim() {
"Write" => Ok(quote! {
impl dos_actors::io::Write<#ident> for #client {
fn write(&mut self) -> Option<std::sync::Arc<dos_actors::io::Data<#ident>>> {
let mut data: std::sync::Arc<dos_actors::io::Data<#name>> = self.write()?;
let inner = std::sync::Arc::get_mut(&mut data)?;
Some(std::sync::Arc::new(inner.into()))
}
}
}),
"Read" => Ok(quote! {
impl dos_actors::io::Read<#ident> for #client {
fn read(&mut self, data: std::sync::Arc<dos_actors::io::Data<#ident>>) {
let inner = std::sync::Arc::get_mut(&mut data).expect("failed to get a mutable reference to data");
<Self as dos_actors::io::Read<#name>>::read(self, std::sync::Arc::new(inner.into())); }
}
}),
"Size" => Ok(quote! {
impl dos_actors::Size<#ident> for #client {
fn len(&self) -> usize {
<Self as dos_actors::Size<#name>>::len(self)
}
}
}),
_ => Err(syn::Error::new(Span::mixed_site(), "missing alias client")),
})
.collect::<syn::Result<Vec<_>>>()
} else {
Err(syn::Error::new(Span::mixed_site(), "missing alias client"))
}
.map(|client_token| {
quote! {
impl UniqueIdentifier for #ident {
type Data = <#name as UniqueIdentifier>::Data;
}
#(#client_token)*
}
})
})
.map(|token| token.into())
}
}
fn get_name_client_traits(attr: &Attribute) -> syn::Result<Alias> {
let client = Client {
name: Err(syn::Error::new(Span::mixed_site(), "missing alias name")),
traits: Err(syn::Error::new(Span::mixed_site(), "missing alias client")),
};
let mut alias = Alias {
name: Err(syn::Error::new(Span::mixed_site(), "missing alias name")),
client,
};
let meta = attr.parse_meta()?;
match meta {
Meta::List(list) => {
for nested in list.nested.iter() {
match nested {
NestedMeta::Meta(Meta::NameValue(nv)) if nv.path.is_ident("name") => {
alias.name = if let Lit::Str(ref val) = nv.lit {
val.parse()
} else {
Err(syn::Error::new_spanned(&nv.lit, "expected String litteral"))
};
Ok(())
}
NestedMeta::Meta(Meta::NameValue(nv)) if nv.path.is_ident("client") => {
alias.client.name = if let Lit::Str(ref val) = nv.lit {
val.parse()
} else {
Err(syn::Error::new_spanned(&nv.lit, "expected String litteral"))
};
Ok(())
}
NestedMeta::Meta(Meta::NameValue(nv)) if nv.path.is_ident("traits") => {
alias.client.traits = if let Lit::Str(ref val) = nv.lit {
Ok(val.value())
} else {
Err(syn::Error::new_spanned(&nv.lit, "expected String litteral"))
};
Ok(())
}
_ => Err(syn::Error::new_spanned(
nested,
"expected `name = \"<value>\"` argument",
)),
}?;
}
Ok(alias)
}
_ => Err(syn::Error::new_spanned(
meta,
"expected a list of attributes",
)),
}
}
