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         #[darling(multiple)]
 162         const_before: Vec<syn::Expr>, // must implement MtSerialize + MtDeserialize + PartialEq
 163
 164         #[darling(multiple)]
 165         const_after: Vec<syn::Expr>, // must implement MtSerialize + MtDeserialize + PartialEq
 166
 167         size: Option<syn::Type>, // must implement MtCfg
 168
 169         len: Option<syn::Type>, // must implement MtCfg
 170
 171         zlib: bool,
 172         zstd: bool, // TODO
 173         default: bool, // type must implement Default
 174 }
 175
 176 type Fields<'a> = Vec<(TokStr, &'a syn::Field)>;
 177
 178 fn get_fields(fields: &syn::Fields, ident: impl Fn(TokStr) -> TokStr) -> Fields {
 179         match fields {
 180                 syn::Fields::Named(fs) => fs
 181                         .named
 182                         .iter()
 183                         .map(|f| (ident(f.ident.as_ref().unwrap().to_token_stream()), f))
 184                         .collect(),
 185                 syn::Fields::Unnamed(fs) => fs
 186                         .unnamed
 187                         .iter()
 188                         .enumerate()
 189                         .map(|(i, f)| (ident(syn::Index::from(i).to_token_stream()), f))
 190                         .collect(),
 191                 syn::Fields::Unit => Vec::new(),
 192         }
 193 }
 194
 195 fn serialize_args(res: darling::Result<MtArgs>, body: impl FnOnce(&MtArgs) -> TokStr) -> TokStr {
 196         match res {
 197                 Ok(args) => {
 198                         let mut code = body(&args);
 199
 200                         if args.zlib {
 201                                 code = quote! {
 202                                         let mut __writer = {
 203                                                 let mut __stream = mt_ser::flate2::write::ZlibEncoder::new(
 204                                                         __writer,
 205                                                         mt_ser::flate2::Compression::default(),
 206                                                 );
 207                                                 let __writer = &mut __stream;
 208                                                 #code
 209                                                 __stream.finish()?
 210                                         };
 211                                 };
 212                         }
 213
 214                         if let Some(size) = args.size {
 215                                 code = quote! {
 216                                         mt_ser::MtSerialize::mt_serialize::<#size>(&{
 217                                                 let mut __buf = Vec::new();
 218                                                 let __writer = &mut __buf;
 219                                                 #code
 220                                                 __buf
 221                                         }, __writer)?;
 222                                 };
 223                         }
 224
 225                         for x in args.const_before.iter().rev() {
 226                                 code = quote! {
 227                                         #x.mt_serialize::<mt_ser::DefCfg>(__writer)?;
 228                                         #code
 229                                 }
 230                         }
 231
 232                         for x in args.const_after.iter() {
 233                                 code = quote! {
 234                                         #code
 235                                         #x.mt_serialize::<mt_ser::DefCfg>(__writer)?;
 236                                 }
 237                         }
 238
 239                         code
 240                 }
 241                 Err(e) => return e.write_errors(),
 242         }
 243 }
 244
 245 fn deserialize_args(res: darling::Result<MtArgs>, body: impl FnOnce(&MtArgs) -> TokStr) -> TokStr {
 246         match res {
 247                 Ok(args) => {
 248                         let mut code = body(&args);
 249
 250                         if args.zlib {
 251                                 code = quote! {
 252                                         {
 253                                                 let mut __owned_reader = mt_ser::flate2::read::ZlibDecoder::new(
 254                                                         mt_ser::WrapRead(__reader));
 255                                                 let __reader = &mut __owned_reader;
 256
 257                                                 #code
 258                                         }
 259                                 }
 260                         }
 261
 262
 263                         if let Some(size) = args.size {
 264                                 code = quote! {
 265                                         #size::mt_deserialize::<DefCfg>(__reader).and_then(|size| {
 266                                                 let mut __owned_reader = std::io::Read::take(
 267                                                         mt_ser::WrapRead(__reader), size as u64);
 268                                                 let __reader = &mut __owned_reader;
 269
 270                                                 #code
 271                                         })
 272                                 };
 273                         }
 274
 275                         let impl_const = |value: TokStr| quote! {
 276                                 {
 277                                         fn deserialize_same_type<T: MtDeserialize>(
 278                                                 _: &T,
 279                                                 reader: &mut impl std::io::Read
 280                                         ) -> Result<T, DeserializeError> {
 281                                                 T::mt_deserialize::<mt_ser::DefCfg>(reader)
 282                                         }
 283
 284                                         deserialize_same_type(&want, __reader)
 285                                                 .and_then(|got| {
 286                                                         if want == got {
 287                                                                 #value
 288                                                         } else {
 289                                                                 Err(mt_ser::DeserializeError::InvalidConst(
 290                                                                         Box::new(want), Box::new(got)
 291                                                                 ))
 292                                                         }
 293                                                 })
 294                                 }
 295                         };
 296
 297                         for want in args.const_before.iter().rev() {
 298                                 let imp = impl_const(code);
 299                                 code = quote! {
 300                                         {
 301                                                 let want = #want;
 302                                                 #imp
 303                                         }
 304                                 };
 305                         }
 306
 307                         for want in args.const_after.iter() {
 308                                 let imp = impl_const(quote! { Ok(value) });
 309                                 code = quote! {
 310                                         {
 311                                                 let want = #want;
 312                                                 #code.and_then(|value| { #imp })
 313                                         }
 314                                 };
 315                         }
 316
 317                         code
 318                 }
 319                 Err(e) => return e.write_errors(),
 320         }
 321 }
 322
 323 fn serialize_fields(fields: &Fields) -> TokStr {
 324         fields
 325                 .iter()
 326                 .map(|(ident, field)| {
 327                         serialize_args(MtArgs::from_field(field), |args| {
 328                                 let def = parse_quote! { mt_ser::DefCfg };
 329                                 let len = args.len.as_ref().unwrap_or(&def);
 330                                 quote! { mt_ser::MtSerialize::mt_serialize::<#len>(#ident, __writer)?; }
 331                         })
 332                 })
 333                 .collect()
 334 }
 335
 336 fn deserialize_fields(fields: &Fields) -> TokStr {
 337         fields
 338                 .iter()
 339                 .map(|(ident, field)| {
 340                         let code = deserialize_args(MtArgs::from_field(field), |args| {
 341                                 let def = parse_quote! { mt_ser::DefCfg };
 342                                 let len = args.len.as_ref().unwrap_or(&def);
 343                                 let mut code = quote! { mt_ser::MtDeserialize::mt_deserialize::<#len>(__reader) };
 344
 345                                 if args.default {
 346                                         code = quote! {
 347                                                 mt_ser::OrDefault::or_default(#code)
 348                                         };
 349                                 }
 350
 351                                 code
 352                         });
 353
 354                         quote! {
 355                                 let #ident = #code?;
 356                         }
 357                 })
 358                 .collect()
 359 }
 360
 361 fn get_fields_struct(input: &syn::Fields) -> (Fields, TokStr) {
 362         let ident_fn = match input {
 363                 syn::Fields::Unnamed(_) => |f| {
 364                         quote! {
 365                                 mt_ser::paste::paste! { [<field_ #f>] }
 366                         }
 367                 },
 368                 _ => |f| quote! { #f },
 369         };
 370
 371         let fields = get_fields(input, ident_fn);
 372         let fields_comma: TokStr = fields
 373                 .iter()
 374                 .rfold(TokStr::new(), |after, (ident, _)| quote! { #ident, #after });
 375
 376         let fields_struct = match input {
 377                 syn::Fields::Named(_) => quote! { { #fields_comma } },
 378                 syn::Fields::Unnamed(_) => quote! { ( #fields_comma ) },
 379                 syn::Fields::Unit => TokStr::new(),
 380         };
 381
 382         (fields, fields_struct)
 383 }
 384
 385 fn get_repr(input: &syn::DeriveInput) -> syn::Type {
 386         input
 387                 .attrs
 388                 .iter()
 389                 .find(|a| a.path.is_ident("repr"))
 390                 .expect("missing repr")
 391                 .parse_args()
 392                 .expect("invalid repr")
 393 }
 394
 395 #[proc_macro_derive(MtSerialize, attributes(mt))]
 396 pub fn derive_serialize(input: TokenStream) -> TokenStream {
 397         let input = parse_macro_input!(input as syn::DeriveInput);
 398         let typename = &input.ident;
 399
 400         let code = serialize_args(MtArgs::from_derive_input(&input), |_| match &input.data {
 401                 syn::Data::Enum(e) => {
 402                         let repr = get_repr(&input);
 403                         let variants: TokStr = e.variants
 404                                 .iter()
 405                                 .fold((parse_quote! { 0 }, TokStr::new()), |(discr, before), v| {
 406                                         let discr = v.discriminant.clone().map(|x| x.1).unwrap_or(discr);
 407                                         let (fields, fields_struct) = get_fields_struct(&v.fields);
 408
 409                                         let code = serialize_args(MtArgs::from_variant(v), |_|
 410                                                 serialize_fields(&fields));
 411                                         let variant = &v.ident;
 412
 413                                         (
 414                                                 parse_quote! { 1 + #discr },
 415                                                 quote! {
 416                                                         #before
 417                                                         #typename::#variant #fields_struct => {
 418                                                                 mt_ser::MtSerialize::mt_serialize::<mt_ser::DefCfg>(&((#discr) as #repr), __writer)?;
 419                                                                 #code
 420                                                         }
 421                                                 }
 422                                         )
 423                                 }).1;
 424
 425                         quote! {
 426                                 match self {
 427                                         #variants
 428                                 }
 429                         }
 430                 }
 431                 syn::Data::Struct(s) => serialize_fields(&get_fields(&s.fields, |f| quote! { &self.#f })),
 432                 _ => {
 433                         panic!("only enum and struct supported");
 434                 }
 435         });
 436
 437         quote! {
 438                 #[automatically_derived]
 439                 impl mt_ser::MtSerialize for #typename {
 440                         fn mt_serialize<C: mt_ser::MtCfg>(&self, __writer: &mut impl std::io::Write) -> Result<(), mt_ser::SerializeError> {
 441                                 #code
 442
 443                                 Ok(())
 444                         }
 445                 }
 446         }.into()
 447 }
 448
 449 #[proc_macro_derive(MtDeserialize, attributes(mt))]
 450 pub fn derive_deserialize(input: TokenStream) -> TokenStream {
 451         let input = parse_macro_input!(input as syn::DeriveInput);
 452         let typename = &input.ident;
 453
 454         let code = deserialize_args(MtArgs::from_derive_input(&input), |_| match &input.data {
 455                 syn::Data::Enum(e) => {
 456                         let repr = get_repr(&input);
 457                         let type_str = typename.to_string();
 458
 459                         let mut consts = TokStr::new();
 460                         let mut arms = TokStr::new();
 461                         let mut discr = parse_quote! { 0 };
 462
 463                         for v in e.variants.iter() {
 464                                 discr = v.discriminant.clone().map(|x| x.1).unwrap_or(discr);
 465
 466                                 let ident = &v.ident;
 467                                 let (fields, fields_struct) = get_fields_struct(&v.fields);
 468                                 let code = deserialize_args(MtArgs::from_variant(v), |_| {
 469                                         let fields_code = deserialize_fields(&fields);
 470
 471                                         quote! {
 472                                                 #fields_code
 473                                                 Ok(Self::#ident #fields_struct)
 474                                         }
 475                                 });
 476
 477                                 consts.extend(quote! {
 478                                         const #ident: #repr = #discr;
 479                                 });
 480
 481                                 arms.extend(quote! {
 482                                         #ident => { #code }
 483                                 });
 484
 485                                 discr = parse_quote! { 1 + #discr };
 486                         }
 487
 488                         quote! {
 489                                 #consts
 490
 491                                 match mt_ser::MtDeserialize::mt_deserialize::<DefCfg>(__reader)? {
 492                                         #arms
 493                                         x => Err(mt_ser::DeserializeError::InvalidEnumVariant(#type_str, x as u64))
 494                                 }
 495                         }
 496                 }
 497                 syn::Data::Struct(s) => {
 498                         let (fields, fields_struct) = get_fields_struct(&s.fields);
 499                         let code = deserialize_fields(&fields);
 500
 501                         quote! {
 502                                 #code
 503                                 Ok(Self #fields_struct)
 504                         }
 505                 }
 506                 _ => {
 507                         panic!("only enum and struct supported");
 508                 }
 509         });
 510
 511         quote! {
 512                 #[automatically_derived]
 513                 impl mt_ser::MtDeserialize for #typename {
 514                         #[allow(non_upper_case_globals)]
 515                         fn mt_deserialize<C: mt_ser::MtCfg>(__reader: &mut impl std::io::Read) -> Result<Self, mt_ser::DeserializeError> {
 516                                 #code
 517                         }
 518                 }
 519         }.into()
 520 }