derive/src/lib.rs

   1 use convert_case::{Case, Casing};
   2 use darling::{FromDeriveInput, FromField, FromMeta, FromVariant};
   3 use proc_macro::TokenStream;
   4 use proc_macro2::TokenStream as TokStr;
   5 use quote::{quote, ToTokens};
   6 use syn::{parse_macro_input, parse_quote};
   7
   8 #[derive(Debug, FromMeta, Copy, Clone, Eq, PartialEq)]
   9 #[darling(rename_all = "snake_case")]
  10 enum To {
  11     Clt,
  12     Srv,
  13 }
  14
  15 #[derive(Debug, FromMeta)]
  16 struct MacroArgs {
  17     to: To,
  18     repr: Option<syn::Type>,
  19     tag: Option<String>,
  20     content: Option<String>,
  21     #[darling(default)]
  22     custom: bool,
  23     #[darling(default)]
  24     enumset: bool,
  25 }
  26
  27 fn wrap_attr(attr: &mut syn::Attribute) {
  28     let path = attr.path.clone();
  29     let tokens = attr.tokens.clone();
  30
  31     match attr.path.get_ident().map(|i| i.to_string()).as_deref() {
  32         Some("mt") => {
  33             *attr = parse_quote! {
  34                 #[cfg_attr(any(feature = "client", feature = "server"), #path #tokens)]
  35             };
  36         }
  37         Some("serde") => {
  38             *attr = parse_quote! {
  39                 #[cfg_attr(feature = "serde", #path #tokens)]
  40             };
  41         }
  42         _ => {}
  43     }
  44 }
  45
  46 #[proc_macro_attribute]
  47 pub fn mt_derive(attr: TokenStream, item: TokenStream) -> TokenStream {
  48     let attr_args = parse_macro_input!(attr as syn::AttributeArgs);
  49     let mut input = parse_macro_input!(item as syn::Item);
  50
  51     let args = match MacroArgs::from_list(&attr_args) {
  52         Ok(v) => v,
  53         Err(e) => {
  54             return TokenStream::from(e.write_errors());
  55         }
  56     };
  57
  58     let (serializer, deserializer) = match args.to {
  59         To::Clt => ("server", "client"),
  60         To::Srv => ("client", "server"),
  61     };
  62
  63     let mut out = quote! {
  64         #[derive(Debug)]
  65         #[cfg_attr(feature = "random", derive(GenerateRandom))]
  66         #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
  67     };
  68
  69     macro_rules! iter {
  70         ($t:expr, $f:expr) => {
  71             $t.iter_mut().for_each($f)
  72         };
  73     }
  74
  75     match &mut input {
  76         syn::Item::Enum(e) => {
  77             iter!(e.attrs, wrap_attr);
  78             iter!(e.variants, |v| {
  79                 iter!(v.attrs, wrap_attr);
  80                 iter!(v.fields, |f| iter!(f.attrs, wrap_attr));
  81             });
  82
  83             if args.enumset {
  84                 let repr_str = args
  85                     .repr
  86                     .expect("missing repr for enum")
  87                     .to_token_stream()
  88                     .to_string();
  89
  90                 out.extend(quote! {
  91                     #[derive(EnumSetType)]
  92                     #[enumset(repr = #repr_str, serialize_as_map)]
  93                 })
  94             } else {
  95                 let has_payload = e
  96                     .variants
  97                     .iter()
  98                     .find_map(|v| if v.fields.is_empty() { None } else { Some(()) })
  99                     .is_some();
 100
 101                 if has_payload {
 102                     let tag = args.tag.expect("missing tag for enum with payload");
 103
 104                     out.extend(quote! {
 105                         #[cfg_attr(feature = "serde", serde(tag = #tag))]
 106                     });
 107
 108                     if let Some(content) = args.content {
 109                         out.extend(quote! {
 110                             #[cfg_attr(feature = "serde", serde(content = #content))]
 111                         });
 112                     }
 113                 } else {
 114                     out.extend(quote! {
 115                         #[derive(Copy, Eq)]
 116                     });
 117                 }
 118
 119                 out.extend(quote! {
 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                 if let Some(repr) = args.repr {
 131                     if repr == parse_quote! { str } {
 132                         out.extend(quote! {
 133                                                         #[cfg_attr(any(feature = "client", feature = "server"), mt(string_repr))]
 134                                                 });
 135                     } else {
 136                         out.extend(quote! {
 137                             #[repr(#repr)]
 138                         });
 139                     }
 140                 } else if !args.custom {
 141                     panic!("missing repr for enum");
 142                 }
 143             }
 144
 145             out.extend(quote! {
 146                 #[cfg_attr(feature = "serde", serde(rename_all = "snake_case"))]
 147             });
 148         }
 149         syn::Item::Struct(s) => {
 150             iter!(s.attrs, wrap_attr);
 151             iter!(s.fields, |f| iter!(f.attrs, wrap_attr));
 152
 153             out.extend(quote! {
 154                 #[derive(Clone, PartialEq)]
 155             });
 156
 157             if !args.custom {
 158                 out.extend(quote! {
 159                     #[cfg_attr(feature = #serializer, derive(MtSerialize))]
 160                     #[cfg_attr(feature = #deserializer, derive(MtDeserialize))]
 161                 });
 162             }
 163         }
 164         _ => panic!("only enum and struct supported"),
 165     }
 166
 167     out.extend(input.to_token_stream());
 168     out.into()
 169 }
 170
 171 #[derive(Debug, Default, FromDeriveInput, FromVariant, FromField)]
 172 #[darling(attributes(mt))]
 173 #[darling(default)]
 174 struct MtArgs {
 175     #[darling(multiple)]
 176     const_before: Vec<syn::Expr>, // must implement MtSerialize + MtDeserialize + PartialEq
 177
 178     #[darling(multiple)]
 179     const_after: Vec<syn::Expr>, // must implement MtSerialize + MtDeserialize + PartialEq
 180
 181     size: Option<syn::Type>, // must implement MtCfg
 182
 183     len: Option<syn::Type>, // must implement MtCfg
 184
 185     zlib: bool,
 186     zstd: bool,    // TODO
 187     default: bool, // type must implement Default
 188
 189     string_repr: bool, // for enums
 190 }
 191
 192 type Fields<'a> = Vec<(TokStr, &'a syn::Field)>;
 193
 194 fn get_fields(fields: &syn::Fields, ident: impl Fn(TokStr) -> TokStr) -> Fields {
 195     match fields {
 196         syn::Fields::Named(fs) => fs
 197             .named
 198             .iter()
 199             .map(|f| (ident(f.ident.as_ref().unwrap().to_token_stream()), f))
 200             .collect(),
 201         syn::Fields::Unnamed(fs) => fs
 202             .unnamed
 203             .iter()
 204             .enumerate()
 205             .map(|(i, f)| (ident(syn::Index::from(i).to_token_stream()), f))
 206             .collect(),
 207         syn::Fields::Unit => Vec::new(),
 208     }
 209 }
 210
 211 fn serialize_args(res: darling::Result<MtArgs>, body: impl FnOnce(&MtArgs) -> TokStr) -> TokStr {
 212     match res {
 213         Ok(args) => {
 214             let mut code = body(&args);
 215
 216             if args.zlib {
 217                 code = quote! {
 218                     let mut __writer = {
 219                         let mut __stream = mt_ser::flate2::write::ZlibEncoder::new(
 220                             __writer,
 221                             mt_ser::flate2::Compression::default(),
 222                         );
 223                         let __writer = &mut __stream;
 224                         #code
 225                         __stream.finish()?
 226                     };
 227                 };
 228             }
 229
 230             if let Some(size) = args.size {
 231                 code = quote! {
 232                     mt_ser::MtSerialize::mt_serialize::<#size>(&{
 233                         let mut __buf = Vec::new();
 234                         let __writer = &mut __buf;
 235                         #code
 236                         __buf
 237                     }, __writer)?;
 238                 };
 239             }
 240
 241             for x in args.const_before.iter().rev() {
 242                 code = quote! {
 243                     #x.mt_serialize::<mt_ser::DefCfg>(__writer)?;
 244                     #code
 245                 }
 246             }
 247
 248             for x in args.const_after.iter() {
 249                 code = quote! {
 250                     #code
 251                     #x.mt_serialize::<mt_ser::DefCfg>(__writer)?;
 252                 }
 253             }
 254
 255             code
 256         }
 257         Err(e) => e.write_errors(),
 258     }
 259 }
 260
 261 fn deserialize_args(res: darling::Result<MtArgs>, body: impl FnOnce(&MtArgs) -> TokStr) -> TokStr {
 262     match res {
 263         Ok(args) => {
 264             let mut code = body(&args);
 265
 266             if args.zlib {
 267                 code = quote! {
 268                     {
 269                         let mut __owned_reader = mt_ser::flate2::read::ZlibDecoder::new(
 270                             mt_ser::WrapRead(__reader));
 271                         let __reader = &mut __owned_reader;
 272
 273                         #code
 274                     }
 275                 }
 276             }
 277
 278             if let Some(size) = args.size {
 279                 code = quote! {
 280                     #size::mt_deserialize::<DefCfg>(__reader).and_then(|size| {
 281                         let mut __owned_reader = std::io::Read::take(
 282                             mt_ser::WrapRead(__reader), size as u64);
 283                         let __reader = &mut __owned_reader;
 284
 285                         #code
 286                     })
 287                 };
 288             }
 289
 290             let impl_const = |value: TokStr| {
 291                 quote! {
 292                     {
 293                         fn deserialize_same_type<T: MtDeserialize>(
 294                             _: &T,
 295                             reader: &mut impl std::io::Read
 296                         ) -> Result<T, mt_ser::DeserializeError> {
 297                             T::mt_deserialize::<mt_ser::DefCfg>(reader)
 298                         }
 299
 300                         deserialize_same_type(&want, __reader)
 301                             .and_then(|got| {
 302                                 if want == got {
 303                                     #value
 304                                 } else {
 305                                     Err(mt_ser::DeserializeError::InvalidConst(
 306                                         Box::new(want), Box::new(got)
 307                                     ))
 308                                 }
 309                             })
 310                     }
 311                 }
 312             };
 313
 314             for want in args.const_before.iter().rev() {
 315                 let imp = impl_const(code);
 316                 code = quote! {
 317                     {
 318                         let want = #want;
 319                         #imp
 320                     }
 321                 };
 322             }
 323
 324             for want in args.const_after.iter() {
 325                 let imp = impl_const(quote! { Ok(value) });
 326                 code = quote! {
 327                     {
 328                         let want = #want;
 329                         #code.and_then(|value| { #imp })
 330                     }
 331                 };
 332             }
 333
 334             code
 335         }
 336         Err(e) => e.write_errors(),
 337     }
 338 }
 339
 340 fn serialize_fields(fields: &Fields) -> TokStr {
 341     fields
 342         .iter()
 343         .map(|(ident, field)| {
 344             serialize_args(MtArgs::from_field(field), |args| {
 345                 let def = parse_quote! { mt_ser::DefCfg };
 346                 let len = args.len.as_ref().unwrap_or(&def);
 347                 quote! { mt_ser::MtSerialize::mt_serialize::<#len>(#ident, __writer)?; }
 348             })
 349         })
 350         .collect()
 351 }
 352
 353 fn deserialize_fields(fields: &Fields) -> TokStr {
 354     fields
 355         .iter()
 356         .map(|(ident, field)| {
 357             let code = deserialize_args(MtArgs::from_field(field), |args| {
 358                 let def = parse_quote! { mt_ser::DefCfg };
 359                 let len = args.len.as_ref().unwrap_or(&def);
 360                 let mut code = quote! { mt_ser::MtDeserialize::mt_deserialize::<#len>(__reader) };
 361
 362                 if args.default {
 363                     code = quote! {
 364                         mt_ser::OrDefault::or_default(#code)
 365                     };
 366                 }
 367
 368                 code
 369             });
 370
 371             quote! {
 372                 let #ident = #code?;
 373             }
 374         })
 375         .collect()
 376 }
 377
 378 fn get_fields_struct(input: &syn::Fields) -> (Fields, TokStr) {
 379     let ident_fn = match input {
 380         syn::Fields::Unnamed(_) => |f| {
 381             quote! {
 382                 mt_ser::paste::paste! { [<field_ #f>] }
 383             }
 384         },
 385         _ => |f| quote! { #f },
 386     };
 387
 388     let fields = get_fields(input, ident_fn);
 389     let fields_comma: TokStr = fields
 390         .iter()
 391         .rfold(TokStr::new(), |after, (ident, _)| quote! { #ident, #after });
 392
 393     let fields_struct = match input {
 394         syn::Fields::Named(_) => quote! { { #fields_comma } },
 395         syn::Fields::Unnamed(_) => quote! { ( #fields_comma ) },
 396         syn::Fields::Unit => TokStr::new(),
 397     };
 398
 399     (fields, fields_struct)
 400 }
 401
 402 fn get_repr(input: &syn::DeriveInput, args: &MtArgs) -> syn::Type {
 403     if args.string_repr {
 404         parse_quote! { &str }
 405     } else {
 406         input
 407             .attrs
 408             .iter()
 409             .find(|a| a.path.is_ident("repr"))
 410             .expect("missing repr")
 411             .parse_args()
 412             .expect("invalid repr")
 413     }
 414 }
 415
 416 fn iter_variants(e: &syn::DataEnum, args: &MtArgs, mut f: impl FnMut(&syn::Variant, &syn::Expr)) {
 417     let mut discr = parse_quote! { 0 };
 418
 419     for v in e.variants.iter() {
 420         discr = if args.string_repr {
 421             let lit = v.ident.to_string().to_case(Case::Snake);
 422             parse_quote! { #lit }
 423         } else {
 424             v.discriminant.clone().map(|x| x.1).unwrap_or(discr)
 425         };
 426
 427         f(v, &discr);
 428
 429         discr = parse_quote! { 1 + #discr };
 430     }
 431 }
 432
 433 #[proc_macro_derive(MtSerialize, attributes(mt))]
 434 pub fn derive_serialize(input: TokenStream) -> TokenStream {
 435     let input = parse_macro_input!(input as syn::DeriveInput);
 436     let typename = &input.ident;
 437
 438     let code = serialize_args(MtArgs::from_derive_input(&input), |args| {
 439         match &input.data {
 440             syn::Data::Enum(e) => {
 441                 let repr = get_repr(&input, args);
 442                 let mut variants = TokStr::new();
 443
 444                 iter_variants(e, args, |v, discr| {
 445                     let (fields, fields_struct) = get_fields_struct(&v.fields);
 446                     let code =
 447                         serialize_args(MtArgs::from_variant(v), |_| serialize_fields(&fields));
 448                     let ident = &v.ident;
 449
 450                     variants.extend(quote! {
 451                                         #typename::#ident #fields_struct => {
 452                                                 mt_ser::MtSerialize::mt_serialize::<mt_ser::DefCfg>(&((#discr) as #repr), __writer)?;
 453                                                 #code
 454                                         }
 455                                 });
 456                 });
 457
 458                 quote! {
 459                     match self {
 460                         #variants
 461                     }
 462                 }
 463             }
 464             syn::Data::Struct(s) => {
 465                 serialize_fields(&get_fields(&s.fields, |f| quote! { &self.#f }))
 466             }
 467             _ => {
 468                 panic!("only enum and struct supported");
 469             }
 470         }
 471     });
 472
 473     quote! {
 474                 #[automatically_derived]
 475                 impl mt_ser::MtSerialize for #typename {
 476                         fn mt_serialize<C: mt_ser::MtCfg>(&self, __writer: &mut impl std::io::Write) -> Result<(), mt_ser::SerializeError> {
 477                                 #code
 478
 479                                 Ok(())
 480                         }
 481                 }
 482         }.into()
 483 }
 484
 485 #[proc_macro_derive(MtDeserialize, attributes(mt))]
 486 pub fn derive_deserialize(input: TokenStream) -> TokenStream {
 487     let input = parse_macro_input!(input as syn::DeriveInput);
 488     let typename = &input.ident;
 489
 490     let code = deserialize_args(MtArgs::from_derive_input(&input), |args| {
 491         match &input.data {
 492             syn::Data::Enum(e) => {
 493                 let repr = get_repr(&input, args);
 494
 495                 let mut consts = TokStr::new();
 496                 let mut arms = TokStr::new();
 497
 498                 iter_variants(e, args, |v, discr| {
 499                     let ident = &v.ident;
 500                     let (fields, fields_struct) = get_fields_struct(&v.fields);
 501                     let code = deserialize_args(MtArgs::from_variant(v), |_| {
 502                         let fields_code = deserialize_fields(&fields);
 503
 504                         quote! {
 505                             #fields_code
 506                             Ok(Self::#ident #fields_struct)
 507                         }
 508                     });
 509
 510                     consts.extend(quote! {
 511                         const #ident: #repr = #discr;
 512                     });
 513
 514                     arms.extend(quote! {
 515                         #ident => { #code }
 516                     });
 517                 });
 518
 519                 let type_str = typename.to_string();
 520                 let discr_match = if args.string_repr {
 521                     quote! {
 522                         let __discr = String::mt_deserialize::<DefCfg>(__reader)?;
 523                         match __discr.as_str()
 524                     }
 525                 } else {
 526                     quote! {
 527                         let __discr = mt_ser::MtDeserialize::mt_deserialize::<DefCfg>(__reader)?;
 528                         match __discr
 529                     }
 530                 };
 531
 532                 quote! {
 533                     #consts
 534
 535                     #discr_match {
 536                         #arms
 537                         _ => Err(mt_ser::DeserializeError::InvalidEnum(#type_str, Box::new(__discr)))
 538                     }
 539                 }
 540             }
 541             syn::Data::Struct(s) => {
 542                 let (fields, fields_struct) = get_fields_struct(&s.fields);
 543                 let code = deserialize_fields(&fields);
 544
 545                 quote! {
 546                     #code
 547                     Ok(Self #fields_struct)
 548                 }
 549             }
 550             _ => {
 551                 panic!("only enum and struct supported");
 552             }
 553         }
 554     });
 555
 556     quote! {
 557                 #[automatically_derived]
 558                 impl mt_ser::MtDeserialize for #typename {
 559                         #[allow(non_upper_case_globals)]
 560                         fn mt_deserialize<C: mt_ser::MtCfg>(__reader: &mut impl std::io::Read) -> Result<Self, mt_ser::DeserializeError> {
 561                                 #code
 562                         }
 563                 }
 564         }.into()
 565 }