derive/src/lib.rs

   1 use darling::{FromDeriveInput, FromField, FromMeta, FromVariant};
   2 use proc_macro::TokenStream;
   3 use proc_macro2::TokenStream as TokStr;
   4 use quote::{quote, ToTokens};
   5 use syn::{parse_macro_input, parse_quote};
   6
   7 #[derive(Debug, FromMeta, Copy, Clone, Eq, PartialEq)]
   8 #[darling(rename_all = "snake_case")]
   9 enum To {
  10         Clt,
  11         Srv,
  12 }
  13
  14 #[derive(Debug, FromMeta)]
  15 struct MacroArgs {
  16         to: To,
  17         repr: Option<syn::Type>,
  18         tag: Option<String>,
  19         content: Option<String>,
  20         #[darling(default)]
  21         custom: bool,
  22         #[darling(default)]
  23         enumset: bool,
  24 }
  25
  26 fn wrap_attr(attr: &mut syn::Attribute) {
  27         let path = attr.path.clone();
  28         let tokens = attr.tokens.clone();
  29
  30         match attr.path.get_ident().map(|i| i.to_string()).as_deref() {
  31                 Some("mt") => {
  32                         *attr = parse_quote! {
  33                                 #[cfg_attr(any(feature = "client", feature = "server"), #path #tokens)]
  34                         };
  35                 }
  36                 Some("serde") => {
  37                         *attr = parse_quote! {
  38                                 #[cfg_attr(feature = "serde", #path #tokens)]
  39                         };
  40                 }
  41                 _ => {}
  42         }
  43 }
  44
  45 #[proc_macro_attribute]
  46 pub fn mt_derive(attr: TokenStream, item: TokenStream) -> TokenStream {
  47         let item2 = item.clone();
  48
  49         let attr_args = parse_macro_input!(attr as syn::AttributeArgs);
  50         let mut input = parse_macro_input!(item2 as syn::Item);
  51
  52         let args = match MacroArgs::from_list(&attr_args) {
  53                 Ok(v) => v,
  54                 Err(e) => {
  55                         return TokenStream::from(e.write_errors());
  56                 }
  57         };
  58
  59         let (serializer, deserializer) = match args.to {
  60                 To::Clt => ("server", "client"),
  61                 To::Srv => ("client", "server"),
  62         };
  63
  64         let mut out = quote! {
  65                 #[derive(Debug)]
  66                 #[cfg_attr(feature = "random", derive(GenerateRandom))]
  67                 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
  68         };
  69
  70         macro_rules! iter {
  71                 ($t:expr, $f:expr) => {
  72                         $t.iter_mut().for_each($f)
  73                 };
  74         }
  75
  76         match &mut input {
  77                 syn::Item::Enum(e) => {
  78                         iter!(e.attrs, wrap_attr);
  79                         iter!(e.variants, |v| {
  80                                 iter!(v.attrs, wrap_attr);
  81                                 iter!(v.fields, |f| iter!(f.attrs, wrap_attr));
  82                         });
  83
  84                         let repr = args.repr.expect("missing repr for enum");
  85
  86                         if args.enumset {
  87                                 let repr_str = repr.to_token_stream().to_string();
  88
  89                                 out.extend(quote! {
  90                                         #[derive(EnumSetType)]
  91                                         #[enumset(repr = #repr_str, serialize_as_map)]
  92                                 })
  93                         } else {
  94                                 let has_payload = e
  95                                         .variants
  96                                         .iter()
  97                                         .find_map(|v| if v.fields.is_empty() { None } else { Some(()) })
  98                                         .is_some();
  99
 100                                 if has_payload {
 101                                         let tag = args.tag.expect("missing tag for enum with payload");
 102
 103                                         out.extend(quote! {
 104                                                 #[cfg_attr(feature = "serde", serde(tag = #tag))]
 105                                         });
 106
 107                                         if let Some(content) = args.content {
 108                                                 out.extend(quote! {
 109                                                         #[cfg_attr(feature = "serde", serde(content = #content))]
 110                                                 });
 111                                         }
 112                                 } else {
 113                                         out.extend(quote! {
 114                                                 #[derive(Copy, Eq)]
 115                                         });
 116                                 }
 117
 118                                 out.extend(quote! {
 119                                         #[repr(#repr)]
 120                                         #[derive(Clone, PartialEq)]
 121                                 });
 122
 123                                 if !args.custom {
 124                                         out.extend(quote! {
 125                                                 #[cfg_attr(feature = #serializer, derive(MtSerialize))]
 126                                                 #[cfg_attr(feature = #deserializer, derive(MtDeserialize))]
 127                                         });
 128                                 }
 129                         }
 130
 131                         out.extend(quote! {
 132                                 #[cfg_attr(feature = "serde", serde(rename_all = "snake_case"))]
 133                         });
 134                 }
 135                 syn::Item::Struct(s) => {
 136                         iter!(s.attrs, wrap_attr);
 137                         iter!(s.fields, |f| iter!(f.attrs, wrap_attr));
 138
 139                         out.extend(quote! {
 140                                 #[derive(Clone, PartialEq)]
 141                         });
 142
 143                         if !args.custom {
 144                                 out.extend(quote! {
 145                                         #[cfg_attr(feature = #serializer, derive(MtSerialize))]
 146                                         #[cfg_attr(feature = #deserializer, derive(MtDeserialize))]
 147                                 });
 148                         }
 149                 }
 150                 _ => panic!("only enum and struct supported"),
 151         }
 152
 153         out.extend(input.to_token_stream());
 154         out.into()
 155 }
 156
 157 #[derive(Debug, Default, FromDeriveInput, FromVariant, FromField)]
 158 #[darling(attributes(mt))]
 159 #[darling(default)]
 160 struct MtArgs {
 161         const8: Option<u8>,
 162         const16: Option<u16>,
 163         const32: Option<u32>,
 164         const64: Option<u64>,
 165         size8: bool,
 166         size16: bool,
 167         size32: bool,
 168         size64: bool,
 169         len0: bool,
 170         len8: bool,
 171         len16: bool,
 172         len32: bool,
 173         len64: bool,
 174         utf16: bool,
 175         zlib: bool,
 176         zstd: bool, // TODO
 177         default: bool,
 178 }
 179
 180 fn get_cfg(args: &MtArgs) -> syn::Type {
 181         let mut ty: syn::Type = parse_quote! { mt_ser::DefCfg  };
 182
 183         if args.len0 {
 184                 ty = parse_quote! { () };
 185         }
 186
 187         macro_rules! impl_len {
 188                 ($name:ident, $T:ty) => {
 189                         if args.$name {
 190                                 ty = parse_quote! { $T  };
 191                         }
 192                 };
 193         }
 194
 195         impl_len!(len8, u8);
 196         impl_len!(len16, u16);
 197         impl_len!(len32, u32);
 198         impl_len!(len64, u64);
 199
 200         if args.utf16 {
 201                 ty = parse_quote! { mt_ser::Utf16<#ty> };
 202         }
 203
 204         ty
 205 }
 206
 207 type Fields<'a> = Vec<(TokStr, &'a syn::Field)>;
 208
 209 fn get_fields(fields: &syn::Fields, ident: impl Fn(TokStr) -> TokStr) -> Fields {
 210         match fields {
 211                 syn::Fields::Named(fs) => fs
 212                         .named
 213                         .iter()
 214                         .map(|f| (ident(f.ident.as_ref().unwrap().to_token_stream()), f))
 215                         .collect(),
 216                 syn::Fields::Unnamed(fs) => fs
 217                         .unnamed
 218                         .iter()
 219                         .enumerate()
 220                         .map(|(i, f)| (ident(i.to_string().to_token_stream()), f))
 221                         .collect(),
 222                 syn::Fields::Unit => Vec::new(),
 223         }
 224 }
 225
 226 fn serialize_args(res: darling::Result<MtArgs>, body: impl FnOnce(&MtArgs) -> TokStr) -> TokStr {
 227         match res {
 228                 Ok(args) => {
 229                         let mut code = TokStr::new();
 230
 231                         macro_rules! impl_const {
 232                                 ($name:ident) => {
 233                                         if let Some(x) = args.$name {
 234                                                 code.extend(quote! {
 235                                                         #x.mt_serialize::<mt_ser::DefCfg>(__writer)?;
 236                                                 });
 237                                         }
 238                                 };
 239                         }
 240
 241                         impl_const!(const8);
 242                         impl_const!(const16);
 243                         impl_const!(const32);
 244                         impl_const!(const64);
 245
 246                         code.extend(body(&args));
 247
 248                         if args.zlib {
 249                                 code = quote! {
 250                                         let mut __writer = {
 251                                                 let mut __stream = mt_ser::flate2::write::ZlibEncoder::new(
 252                                                         __writer,
 253                                                         mt_ser::flate2::Compression::default(),
 254                                                 );
 255                                                 let __writer = &mut __stream;
 256                                                 #code
 257                                                 __stream.finish()?
 258                                         };
 259                                 };
 260                         }
 261
 262                         macro_rules! impl_size {
 263                                 ($name:ident, $T:ty) => {
 264                                         if args.$name {
 265                                                 code = quote! {
 266                                                                 mt_ser::MtSerialize::mt_serialize::<$T>(&{
 267                                                                         let mut __buf = Vec::new();
 268                                                                         let __writer = &mut __buf;
 269                                                                         #code
 270                                                                         __buf
 271                                                                 }, __writer)?;
 272                                                 };
 273                                         }
 274                                 };
 275                         }
 276
 277                         impl_size!(size8, u8);
 278                         impl_size!(size16, u16);
 279                         impl_size!(size32, u32);
 280                         impl_size!(size64, u64);
 281
 282                         code
 283                 }
 284                 Err(e) => return e.write_errors(),
 285         }
 286 }
 287
 288 fn serialize_fields(fields: &Fields) -> TokStr {
 289         fields
 290                 .iter()
 291                 .map(|(ident, field)| {
 292                         serialize_args(MtArgs::from_field(field), |args| {
 293                                 let cfg = get_cfg(args);
 294                                 quote! { mt_ser::MtSerialize::mt_serialize::<#cfg>(#ident, __writer)?; }
 295                         })
 296                 })
 297                 .collect()
 298 }
 299
 300 #[proc_macro_derive(MtSerialize, attributes(mt))]
 301 pub fn derive_serialize(input: TokenStream) -> TokenStream {
 302         let input = parse_macro_input!(input as syn::DeriveInput);
 303         let typename = &input.ident;
 304
 305         let code = serialize_args(MtArgs::from_derive_input(&input), |_| match &input.data {
 306                 syn::Data::Enum(e) => {
 307                         let repr: syn::Type = input
 308                                 .attrs
 309                                 .iter()
 310                                 .find(|a| a.path.is_ident("repr"))
 311                                 .expect("missing repr")
 312                                 .parse_args()
 313                                 .expect("invalid repr");
 314
 315                         let variants: TokStr = e.variants
 316                                 .iter()
 317                                 .fold((parse_quote! { 0 }, TokStr::new()), |(discr, before), v| {
 318                                         let discr = v.discriminant.clone().map(|x| x.1).unwrap_or(discr);
 319
 320                                         let ident_fn = match &v.fields {
 321                                                 syn::Fields::Unnamed(_) => |f| quote! {
 322                                                         mt_ser::paste::paste! { [<field_ #f>] }
 323                                                 },
 324                                                 _ => |f| quote! { #f },
 325                                         };
 326
 327                                         let fields = get_fields(&v.fields, ident_fn);
 328                                         let fields_comma: TokStr = fields.iter()
 329                                                 .rfold(TokStr::new(), |after, (ident, _)| quote! { #ident, #after });
 330
 331                                         let destruct = match &v.fields {
 332                                                 syn::Fields::Named(_) => quote! { { #fields_comma } },
 333                                                 syn::Fields::Unnamed(_) => quote! { ( #fields_comma ) },
 334                                                 syn::Fields::Unit => TokStr::new(),
 335                                         };
 336
 337                                         let code = serialize_args(MtArgs::from_variant(v), |_|
 338                                                 serialize_fields(&fields));
 339                                         let variant = &v.ident;
 340
 341                                         (
 342                                                 parse_quote! { 1 + #discr },
 343                                                 quote! {
 344                                                         #before
 345                                                         #typename::#variant #destruct => {
 346                                                                 mt_ser::MtSerialize::mt_serialize::<mt_ser::DefCfg>(&((#discr) as #repr), __writer)?;
 347                                                                 #code
 348                                                         }
 349                                                 }
 350                                         )
 351                                 }).1;
 352
 353                         quote! {
 354                                 match self {
 355                                         #variants
 356                                 }
 357                         }
 358                 }
 359                 syn::Data::Struct(s) => serialize_fields(&get_fields(&s.fields, |f| quote! { &self.#f })),
 360                 _ => {
 361                         panic!("only enum and struct supported");
 362                 }
 363         });
 364
 365         quote! {
 366                 #[automatically_derived]
 367                 impl mt_ser::MtSerialize for #typename {
 368                         fn mt_serialize<C: mt_ser::MtCfg>(&self, __writer: &mut impl std::io::Write) -> Result<(), mt_ser::SerializeError> {
 369                                 #code
 370
 371                                 Ok(())
 372                         }
 373                 }
 374         }.into()
 375 }
 376
 377 #[proc_macro_derive(MtDeserialize, attributes(mt))]
 378 pub fn derive_deserialize(input: TokenStream) -> TokenStream {
 379         let syn::DeriveInput {
 380                 ident: typename, ..
 381         } = parse_macro_input!(input);
 382         quote! {
 383                 #[automatically_derived]
 384                 impl mt_ser::MtDeserialize for #typename {
 385                         fn mt_deserialize<C: mt_ser::MtCfg>(__reader: &mut impl std::io::Read) -> Result<Self, mt_ser::DeserializeError> {
 386                                 Err(mt_ser::DeserializeError::Unimplemented)
 387                         }
 388                 }
 389         }.into()
 390 }