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|
use proc_macro::TokenStream;
use proc_macro2::{Ident, Span};
use quote::{format_ident, quote};
use syn::{
parse_macro_input, punctuated::Punctuated, DeriveInput, Field, Fields, LitStr, Token, Type,
};
pub fn derive_request(input: TokenStream) -> TokenStream {
let input = parse_macro_input!(input as DeriveInput);
let name = &input.ident;
// Disallow Generic structs
if !input.generics.params.is_empty() {
return syn::Error::new(Span::call_site(), "Request structs cannot be generic")
.into_compile_error()
.into();
}
let RequestAttrs {
endpoint,
method,
auth,
response,
} = match derive_request_attrs(&input) {
Ok(a) => a,
Err(e) => return e.to_compile_error().into(),
};
let Some(response) = response else {
return syn::Error::new(
Span::call_site(),
"missing #[trakt(response = \"...\")] attribute",
)
.into_compile_error()
.into();
};
let SerializeStructs {
q_ident,
p_ident,
stream,
} = match derive_request_structs(&input, &endpoint.value()) {
Ok(s) => s,
Err(e) => return e.to_compile_error().into(),
};
let expanded = quote! {
#stream
#[automatically_derived]
impl crate::Request for #name {
type Response = #response;
const METADATA: crate::Metadata = crate::Metadata {
endpoint: #endpoint,
method: ::http::Method::#method,
auth: #auth,
};
fn try_into_http_request<T: Default + ::bytes::BufMut>(
self,
ctx: crate::Context,
) -> Result<::http::Request<T>, crate::IntoHttpError> {
let (path, query): (#p_ident, #q_ident) = self.into();
let url = crate::url::construct_url(
ctx.base_url,
#endpoint,
&path,
&query,
)?;
let request = ::http::Request::builder()
.method(Self::METADATA.method)
.uri(url)
.header("Content-Type", "application/json")
.header("trakt-api-version", "2")
.header("trakt-api-key", ctx.client_id)
.body(T::default())?;
Ok(request)
}
}
};
TokenStream::from(expanded)
}
fn parse_url_params(endpoint: &str) -> Vec<&str> {
let mut params = vec![];
for (i, c) in endpoint.char_indices() {
if c == '{' {
let end = endpoint[i..].find('}').unwrap();
params.push(&endpoint[i + 1..i + end]);
}
}
params
}
struct RequestAttrs {
endpoint: LitStr,
method: Ident,
auth: bool,
response: Option<Type>,
}
fn derive_request_attrs(input: &DeriveInput) -> syn::Result<RequestAttrs> {
let mut ret = RequestAttrs {
endpoint: LitStr::new("/", Span::call_site()),
method: format_ident!("GET"),
auth: false,
response: None,
};
for attr in &input.attrs {
if attr.path().is_ident("trakt") {
attr.parse_nested_meta(|meta| {
if meta.path.is_ident("response") {
let value = meta.value()?;
ret.response = Some(value.parse()?);
Ok(())
} else if meta.path.is_ident("endpoint") {
let value = meta.value()?;
ret.endpoint = value.parse()?;
Ok(())
} else if meta.path.is_ident("method") {
let value = meta.value()?;
ret.method = value.parse()?;
Ok(())
} else if meta.path.is_ident("auth") {
ret.auth = true;
Ok(())
} else {
Err(meta.error("unsupported attribute"))
}
})?;
}
}
Ok(ret)
}
struct SerializeStructs {
q_ident: Ident,
p_ident: Ident,
stream: proc_macro2::TokenStream,
}
fn derive_request_structs(input: &DeriveInput, endpoint: &str) -> syn::Result<SerializeStructs> {
let syn::Data::Struct(data) = &input.data else {
return Err(syn::Error::new(
Span::call_site(),
"Request structs must be structs",
));
};
match &data.fields {
Fields::Named(f) => Ok(make_structs(&input.ident, &f.named, endpoint)),
Fields::Unnamed(_) => Err(syn::Error::new(
Span::call_site(),
"Request structs cannot have unnamed fields",
)),
Fields::Unit => Ok(make_structs(&input.ident, &Punctuated::new(), endpoint)),
}
}
fn make_structs(
ident: &Ident,
fields: &Punctuated<Field, Token![,]>,
endpoint: &str,
) -> SerializeStructs {
let path_params_str = parse_url_params(endpoint);
let mut path_params = Punctuated::<_, Token![,]>::new();
let mut query_params = Punctuated::<_, Token![,]>::new();
for field in fields {
let ident = field.ident.as_ref().unwrap();
if path_params_str.contains(&&*ident.to_string()) {
path_params.push(field);
} else {
query_params.push(field);
}
}
let q_ident = format_ident!("{}QueryParams", ident);
let p_ident = format_ident!("{}PathParams", ident);
let p_names = path_params.iter().map(|f| &f.ident).collect::<Vec<_>>();
let q_names = query_params.iter().map(|f| &f.ident).collect::<Vec<_>>();
let stream = quote! {
#[doc(hidden)]
#[derive(Debug, Clone, ::serde::Serialize)]
struct #q_ident {
#query_params
}
#[doc(hidden)]
#[derive(Debug, Clone, ::serde::Serialize)]
struct #p_ident {
#path_params
}
impl std::convert::From<#ident> for (#p_ident, #q_ident) {
fn from(req: #ident) -> Self {
let #ident { #(#p_names,)* #(#q_names,)* } = req;
(#p_ident { #(#p_names,)* }, #q_ident { #(#q_names,)* })
}
}
};
SerializeStructs {
q_ident,
p_ident,
stream,
}
}
|
