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                 out.extend(quote! {
  85                     #[derive(EnumSetType)]
  86                     #[enumset(serialize_as_map)]
  87                 });
  88
  89                 if let Some(repr) = args.repr {
  90                     let repr_str = repr.to_token_stream().to_string();
  91
  92                     out.extend(quote! {
  93                         #[enumset(repr = #repr_str)]
  94                     });
  95                 } else if !args.custom {
  96                     panic!("missing repr for enum");
  97                 }
  98             } else {
  99                 let has_payload = e
 100                     .variants
 101                     .iter()
 102                     .find_map(|v| if v.fields.is_empty() { None } else { Some(()) })
 103                     .is_some();
 104
 105                 if has_payload {
 106                     let tag = args.tag.expect("missing tag for enum with payload");
 107
 108                     out.extend(quote! {
 109                         #[cfg_attr(feature = "serde", serde(tag = #tag))]
 110                     });
 111
 112                     if let Some(content) = args.content {
 113                         out.extend(quote! {
 114                             #[cfg_attr(feature = "serde", serde(content = #content))]
 115                         });
 116                     }
 117                 } else {
 118                     out.extend(quote! {
 119                         #[derive(Copy, Eq)]
 120                     });
 121                 }
 122
 123                 out.extend(quote! {
 124                     #[derive(Clone, PartialEq)]
 125                 });
 126
 127                 if !args.custom {
 128                     out.extend(quote! {
 129                         #[cfg_attr(feature = #serializer, derive(MtSerialize))]
 130                         #[cfg_attr(feature = #deserializer, derive(MtDeserialize))]
 131                     });
 132                 }
 133
 134                 if let Some(repr) = args.repr {
 135                     if repr == parse_quote! { str } {
 136                         out.extend(quote! {
 137                                                         #[cfg_attr(any(feature = "client", feature = "server"), mt(string_repr))]
 138                                                 });
 139                     } else {
 140                         out.extend(quote! {
 141                             #[repr(#repr)]
 142                         });
 143                     }
 144                 } else if !args.custom {
 145                     panic!("missing repr for enum");
 146                 }
 147             }
 148
 149             out.extend(quote! {
 150                 #[cfg_attr(feature = "serde", serde(rename_all = "snake_case"))]
 151             });
 152         }
 153         syn::Item::Struct(s) => {
 154             iter!(s.attrs, wrap_attr);
 155             iter!(s.fields, |f| iter!(f.attrs, wrap_attr));
 156
 157             out.extend(quote! {
 158                 #[derive(Clone, PartialEq)]
 159             });
 160
 161             if !args.custom {
 162                 out.extend(quote! {
 163                     #[cfg_attr(feature = #serializer, derive(MtSerialize))]
 164                     #[cfg_attr(feature = #deserializer, derive(MtDeserialize))]
 165                 });
 166             }
 167         }
 168         _ => panic!("only enum and struct supported"),
 169     }
 170
 171     out.extend(input.to_token_stream());
 172     out.into()
 173 }
 174
 175 #[derive(Debug, Default, FromDeriveInput, FromVariant, FromField)]
 176 #[darling(attributes(mt))]
 177 #[darling(default)]
 178 struct MtArgs {
 179     #[darling(multiple)]
 180     const_before: Vec<syn::Expr>, // must implement MtSerialize + MtDeserialize + PartialEq
 181     #[darling(multiple)]
 182     const_after: Vec<syn::Expr>, // must implement MtSerialize + MtDeserialize + PartialEq
 183     size: Option<syn::Type>, // must implement MtCfg
 184     len: Option<syn::Type>,  // must implement MtCfg
 185     default: bool,           // type must implement Default
 186     string_repr: bool,       // for enums
 187     zlib: bool,
 188     zstd: bool,
 189     typename: Option<syn::Ident>, // remote derive
 190     bounds: Option<syn::WhereClause>,
 191 }
 192
 193 type Fields<'a> = Vec<(TokStr, &'a syn::Field)>;
 194
 195 fn get_fields(fields: &syn::Fields, ident: impl Fn(TokStr) -> TokStr) -> Fields {
 196     match fields {
 197         syn::Fields::Named(fs) => fs
 198             .named
 199             .iter()
 200             .map(|f| (ident(f.ident.as_ref().unwrap().to_token_stream()), f))
 201             .collect(),
 202         syn::Fields::Unnamed(fs) => fs
 203             .unnamed
 204             .iter()
 205             .enumerate()
 206             .map(|(i, f)| (ident(syn::Index::from(i).to_token_stream()), f))
 207             .collect(),
 208         syn::Fields::Unit => Vec::new(),
 209     }
 210 }
 211
 212 fn serialize_args(args: &MtArgs, code: &mut TokStr) {
 213     macro_rules! impl_compress {
 214         ($create:expr) => {
 215             *code = quote! {
 216                 let mut __writer = {
 217                     let mut __stream = $create;
 218                     let __writer = &mut __stream;
 219                     #code
 220                     __stream.finish()?
 221                 };
 222             };
 223         };
 224     }
 225
 226     if args.zlib {
 227         impl_compress!(mt_ser::flate2::write::ZlibEncoder::new(
 228             __writer,
 229             mt_ser::flate2::Compression::default()
 230         ));
 231     }
 232
 233     if args.zstd {
 234         impl_compress!(mt_ser::zstd::stream::write::Encoder::new(__writer, 0)?);
 235     }
 236
 237     if let Some(size) = &args.size {
 238         *code = quote! {
 239             mt_ser::MtSerialize::mt_serialize::<#size>(&{
 240                 let mut __buf = Vec::new();
 241                 let __writer = &mut __buf;
 242                 #code
 243                 __buf
 244             }, __writer)?;
 245         };
 246     }
 247
 248     for x in args.const_before.iter().rev() {
 249         *code = quote! {
 250             #x.mt_serialize::<mt_ser::DefCfg>(__writer)?;
 251             #code
 252         }
 253     }
 254
 255     for x in args.const_after.iter() {
 256         *code = quote! {
 257             #code
 258             #x.mt_serialize::<mt_ser::DefCfg>(__writer)?;
 259         }
 260     }
 261 }
 262
 263 fn deserialize_args(args: &MtArgs, code: &mut TokStr) {
 264     macro_rules! impl_compress {
 265         ($create:expr) => {
 266             *code = quote! {
 267                 {
 268                     let mut __owned_reader = $create;
 269                     let __reader = &mut __owned_reader;
 270
 271                     #code
 272                 }
 273             }
 274         };
 275     }
 276
 277     if args.zlib {
 278         impl_compress!(mt_ser::flate2::read::ZlibDecoder::new(mt_ser::WrapRead(
 279             __reader
 280         )));
 281     }
 282
 283     if args.zstd {
 284         impl_compress!(mt_ser::zstd::stream::read::Decoder::new(mt_ser::WrapRead(
 285             __reader
 286         ))?);
 287     }
 288
 289     if let Some(size) = &args.size {
 290         *code = quote! {
 291             #size::mt_deserialize::<DefCfg>(__reader).and_then(|size| {
 292                 let mut __owned_reader = std::io::Read::take(
 293                     mt_ser::WrapRead(__reader), size as u64);
 294                 let __reader = &mut __owned_reader;
 295
 296                 #code
 297             })
 298         };
 299     }
 300
 301     let impl_const = |value: &TokStr| {
 302         quote! {
 303             {
 304                 fn deserialize_same_type<T: MtDeserialize>(
 305                     _: &T,
 306                     reader: &mut impl std::io::Read
 307                 ) -> Result<T, mt_ser::DeserializeError> {
 308                     T::mt_deserialize::<mt_ser::DefCfg>(reader)
 309                 }
 310
 311                 deserialize_same_type(&want, __reader)
 312                     .and_then(|got| {
 313                         if want == got {
 314                             #value
 315                         } else {
 316                             Err(mt_ser::DeserializeError::InvalidConst(
 317                                 Box::new(want), Box::new(got)
 318                             ))
 319                         }
 320                     })
 321             }
 322         }
 323     };
 324
 325     for want in args.const_before.iter().rev() {
 326         let imp = impl_const(&code);
 327         *code = quote! {
 328             {
 329                 let want = #want;
 330                 #imp
 331             }
 332         };
 333     }
 334
 335     for want in args.const_after.iter() {
 336         let imp = impl_const(&quote! { Ok(value) });
 337         *code = quote! {
 338             {
 339                 let want = #want;
 340                 #code.and_then(|value| { #imp })
 341             }
 342         };
 343     }
 344 }
 345
 346 fn serialize_fields(fields: &Fields) -> TokStr {
 347     fields
 348         .iter()
 349         .map(|(ident, field)| {
 350             let args = MtArgs::from_field(field).unwrap();
 351             let def = parse_quote! { mt_ser::DefCfg };
 352             let len = args.len.as_ref().unwrap_or(&def);
 353
 354             let mut code = quote! { mt_ser::MtSerialize::mt_serialize::<#len>(#ident, __writer)?; };
 355             serialize_args(&args, &mut code);
 356
 357             code
 358         })
 359         .collect()
 360 }
 361
 362 fn deserialize_fields(fields: &Fields) -> TokStr {
 363     fields
 364         .iter()
 365         .map(|(ident, field)| {
 366             let args = MtArgs::from_field(field).unwrap();
 367
 368             let def = parse_quote! { mt_ser::DefCfg };
 369             let len = args.len.as_ref().unwrap_or(&def);
 370             let mut code = quote! { mt_ser::MtDeserialize::mt_deserialize::<#len>(__reader) };
 371
 372             if args.default {
 373                 code = quote! {
 374                     mt_ser::OrDefault::or_default(#code)
 375                 };
 376             }
 377
 378             deserialize_args(&args, &mut code);
 379
 380             quote! {
 381                 let #ident = #code?;
 382             }
 383         })
 384         .collect()
 385 }
 386
 387 fn get_fields_struct(input: &syn::Fields) -> (Fields, TokStr) {
 388     let ident_fn = match input {
 389         syn::Fields::Unnamed(_) => |f| {
 390             quote! {
 391                 mt_ser::paste::paste! { [<field_ #f>] }
 392             }
 393         },
 394         _ => |f| quote! { #f },
 395     };
 396
 397     let fields = get_fields(input, ident_fn);
 398     let fields_comma: TokStr = fields
 399         .iter()
 400         .rfold(TokStr::new(), |after, (ident, _)| quote! { #ident, #after });
 401
 402     let fields_struct = match input {
 403         syn::Fields::Named(_) => quote! { { #fields_comma } },
 404         syn::Fields::Unnamed(_) => quote! { ( #fields_comma ) },
 405         syn::Fields::Unit => TokStr::new(),
 406     };
 407
 408     (fields, fields_struct)
 409 }
 410
 411 fn get_repr(input: &syn::DeriveInput, args: &MtArgs) -> syn::Type {
 412     if args.string_repr {
 413         parse_quote! { &str }
 414     } else {
 415         input
 416             .attrs
 417             .iter()
 418             .find(|a| a.path.is_ident("repr"))
 419             .expect("missing repr")
 420             .parse_args()
 421             .expect("invalid repr")
 422     }
 423 }
 424
 425 fn iter_variants(e: &syn::DataEnum, args: &MtArgs, mut f: impl FnMut(&syn::Variant, &syn::Expr)) {
 426     let mut discr = parse_quote! { 0 };
 427
 428     for v in e.variants.iter() {
 429         discr = if args.string_repr {
 430             let lit = v.ident.to_string().to_case(Case::Snake);
 431             parse_quote! { #lit }
 432         } else {
 433             v.discriminant.clone().map(|x| x.1).unwrap_or(discr)
 434         };
 435
 436         f(v, &discr);
 437
 438         discr = parse_quote! { 1 + #discr };
 439     }
 440 }
 441
 442 fn make_impl(
 443     traitname: TokStr,
 444     input: &syn::DeriveInput,
 445     typename: &syn::Ident,
 446     args: &MtArgs,
 447     code: TokStr,
 448 ) -> TokenStream {
 449     let generics = &input.generics;
 450     let bounds = args.bounds.clone().or_else(|| {
 451         if generics.params.is_empty() {
 452             None
 453         } else {
 454             Some(
 455                 syn::parse(
 456                     generics
 457                         .params
 458                         .iter()
 459                         .rfold(quote! { where }, |before, t| match t {
 460                             syn::GenericParam::Type(x) => quote! { #before #x: #traitname, },
 461                             _ => before,
 462                         })
 463                         .into(),
 464                 )
 465                 .expect("invalid where clause"),
 466             )
 467         }
 468     });
 469
 470     quote! {
 471         #[automatically_derived]
 472         impl #generics #traitname for #typename #generics #bounds { #code }
 473     }
 474     .into()
 475 }
 476
 477 #[proc_macro_derive(MtSerialize, attributes(mt))]
 478 pub fn derive_serialize(input: TokenStream) -> TokenStream {
 479     let input = parse_macro_input!(input as syn::DeriveInput);
 480     let args = MtArgs::from_derive_input(&input).unwrap();
 481     let typename = args.typename.as_ref().unwrap_or(&input.ident);
 482
 483     let mut code = match &input.data {
 484         syn::Data::Enum(e) => {
 485             let repr = get_repr(&input, &args);
 486             let mut variants = TokStr::new();
 487
 488             iter_variants(e, &args, |v, discr| {
 489                 let args = MtArgs::from_variant(v).unwrap();
 490
 491                 let (fields, fields_struct) = get_fields_struct(&v.fields);
 492
 493                 let mut code = serialize_fields(&fields);
 494                 serialize_args(&args, &mut code);
 495
 496                 let ident = &v.ident;
 497
 498                 variants.extend(quote! {
 499                                         #typename::#ident #fields_struct => {
 500                                                 mt_ser::MtSerialize::mt_serialize::<mt_ser::DefCfg>(&((#discr) as #repr), __writer)?;
 501                                                 #code
 502                                         }
 503                                 });
 504             });
 505
 506             quote! {
 507                 match self {
 508                     #variants
 509                 }
 510             }
 511         }
 512         syn::Data::Struct(s) => serialize_fields(&get_fields(&s.fields, |f| quote! { &self.#f })),
 513         _ => {
 514             panic!("only enum and struct supported");
 515         }
 516     };
 517
 518     serialize_args(&args, &mut code);
 519
 520     make_impl(
 521         quote! { mt_ser::MtSerialize },
 522         &input,
 523         typename,
 524         &args,
 525         quote! {
 526             fn mt_serialize<C: mt_ser::MtCfg>(&self, __writer: &mut impl std::io::Write) -> Result<(), mt_ser::SerializeError> {
 527                 #code
 528
 529                 Ok(())
 530             }
 531         },
 532     )
 533 }
 534
 535 #[proc_macro_derive(MtDeserialize, attributes(mt))]
 536 pub fn derive_deserialize(input: TokenStream) -> TokenStream {
 537     let input = parse_macro_input!(input as syn::DeriveInput);
 538     let args = MtArgs::from_derive_input(&input).unwrap();
 539     let typename = args.typename.as_ref().unwrap_or(&input.ident);
 540
 541     let mut code = match &input.data {
 542         syn::Data::Enum(e) => {
 543             let repr = get_repr(&input, &args);
 544
 545             let mut consts = TokStr::new();
 546             let mut arms = TokStr::new();
 547
 548             iter_variants(e, &args, |v, discr| {
 549                 let args = MtArgs::from_variant(v).unwrap();
 550
 551                 let ident = &v.ident;
 552                 let (fields, fields_struct) = get_fields_struct(&v.fields);
 553                 let mut code = deserialize_fields(&fields);
 554                 code = quote! {
 555                     #code
 556                     Ok(Self::#ident #fields_struct)
 557                 };
 558
 559                 deserialize_args(&args, &mut code);
 560
 561                 consts.extend(quote! {
 562                     const #ident: #repr = #discr;
 563                 });
 564
 565                 arms.extend(quote! {
 566                     #ident => { #code }
 567                 });
 568             });
 569
 570             let type_str = typename.to_string();
 571             let discr_match = if args.string_repr {
 572                 quote! {
 573                     let __discr = String::mt_deserialize::<DefCfg>(__reader)?;
 574                     match __discr.as_str()
 575                 }
 576             } else {
 577                 quote! {
 578                     let __discr = mt_ser::MtDeserialize::mt_deserialize::<DefCfg>(__reader)?;
 579                     match __discr
 580                 }
 581             };
 582
 583             quote! {
 584                 #consts
 585
 586                 #discr_match {
 587                     #arms
 588                     _ => Err(mt_ser::DeserializeError::InvalidEnum(#type_str, Box::new(__discr)))
 589                 }
 590             }
 591         }
 592         syn::Data::Struct(s) => {
 593             let (fields, fields_struct) = get_fields_struct(&s.fields);
 594             let code = deserialize_fields(&fields);
 595
 596             quote! {
 597                 #code
 598                 Ok(Self #fields_struct)
 599             }
 600         }
 601         _ => {
 602             panic!("only enum and struct supported");
 603         }
 604     };
 605
 606     deserialize_args(&args, &mut code);
 607
 608     make_impl(
 609         quote! { mt_ser::MtDeserialize },
 610         &input,
 611         typename,
 612         &args,
 613         quote! {
 614             #[allow(non_upper_case_globals)]
 615             fn mt_deserialize<C: mt_ser::MtCfg>(__reader: &mut impl std::io::Read) -> Result<Self, mt_ser::DeserializeError> {
 616                 #code
 617             }
 618         },
 619     )
 620 }