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|
use darling::FromMeta;
use proc_macro::{self, TokenStream};
use quote::{quote, ToTokens};
use syn::{parse_macro_input, parse_quote};
#[derive(Debug, FromMeta, Copy, Clone, Eq, PartialEq)]
#[darling(rename_all = "snake_case")]
enum To {
Clt,
Srv,
}
#[derive(Debug, FromMeta)]
struct MacroArgs {
to: To,
repr: Option<syn::Type>,
tag: Option<String>,
content: Option<String>,
#[darling(default)]
enumset: bool,
}
fn wrap_attr(attr: &mut syn::Attribute) {
match attr.path.get_ident().map(|i| i.to_string()).as_deref() {
Some("mt") => {
let path = attr.path.clone();
let tokens = attr.tokens.clone();
*attr = parse_quote! {
#[cfg_attr(any(feature = "client", feature = "server"), #path #tokens)]
};
}
Some("serde") => {
let path = attr.path.clone();
let tokens = attr.tokens.clone();
*attr = parse_quote! {
#[cfg_attr(feature = "serde", #path #tokens)]
};
}
_ => {}
}
}
#[proc_macro_attribute]
pub fn mt_derive(attr: TokenStream, item: TokenStream) -> TokenStream {
let item2 = item.clone();
let attr_args = parse_macro_input!(attr as syn::AttributeArgs);
let mut input = parse_macro_input!(item2 as syn::Item);
let args = match MacroArgs::from_list(&attr_args) {
Ok(v) => v,
Err(e) => {
return TokenStream::from(e.write_errors());
}
};
let (serializer, deserializer) = match args.to {
To::Clt => ("server", "client"),
To::Srv => ("client", "server"),
};
let mut out = quote! {
#[derive(Debug)]
#[cfg_attr(feature = "random", derive(GenerateRandom))]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
};
macro_rules! iter {
($t:expr, $f:expr) => {
$t.iter_mut().for_each($f)
};
}
match &mut input {
syn::Item::Enum(e) => {
iter!(e.attrs, wrap_attr);
iter!(e.variants, |v| {
iter!(v.attrs, wrap_attr);
iter!(v.fields, |f| iter!(f.attrs, wrap_attr));
});
let repr = args.repr.expect("missing repr for enum");
if args.enumset {
let repr_str = repr.to_token_stream().to_string();
out.extend(quote! {
#[derive(EnumSetType)]
#[enumset(repr = #repr_str, serialize_as_map)]
})
} else {
let has_payload = e
.variants
.iter()
.find_map(|v| if v.fields.is_empty() { None } else { Some(()) })
.is_some();
if has_payload {
let tag = args.tag.expect("missing tag for enum with payload");
out.extend(quote! {
#[derive(Clone)]
#[cfg_attr(feature = "serde", serde(tag = #tag))]
});
if let Some(content) = args.content {
out.extend(quote! {
#[cfg_attr(feature = "serde", serde(content = #content))]
});
}
} else {
out.extend(quote! {
#[derive(Copy, Clone, PartialEq, Eq)]
});
}
out.extend(quote! {
#[repr(#repr)]
#[cfg_attr(feature = #serializer, derive(MtSerialize))]
#[cfg_attr(feature = #deserializer, derive(MtDeserialize))]
});
}
out.extend(quote! {
#[cfg_attr(feature = "serde", serde(rename_all = "snake_case"))]
});
}
syn::Item::Struct(s) => {
iter!(s.attrs, wrap_attr);
iter!(s.fields, |f| iter!(f.attrs, wrap_attr));
out.extend(quote! {
#[derive(Clone)]
#[cfg_attr(feature = #serializer, derive(MtSerialize))]
#[cfg_attr(feature = #deserializer, derive(MtDeserialize))]
});
}
_ => panic!("only enum and struct supported"),
}
out.extend(input.to_token_stream());
out.into()
}
#[proc_macro_derive(MtSerialize, attributes(mt))]
pub fn derive_serialize(input: TokenStream) -> TokenStream {
let syn::DeriveInput { ident, .. } = parse_macro_input!(input);
let output = quote! {
impl MtSerialize for #ident {
fn mt_serialize<W: std::io::Write>(&self, writer: &mut W) -> Result<(), mt_data::SerializeError> {
Err(mt_data::SerializeError::Unimplemented)
}
}
};
output.into()
}
#[proc_macro_derive(MtDeserialize, attributes(mt))]
pub fn derive_deserialize(input: TokenStream) -> TokenStream {
let syn::DeriveInput { ident, .. } = parse_macro_input!(input);
quote! {
impl MtDeserialize for #ident {
fn mt_deserialize<R: std::io::Read>(reader: &mut R) -> Result<Self, mt_data::DeserializeError> {
Err(mt_data::DeserializeError::Unimplemented)
}
}
}.into()
}
|
