1 use proc_macro2::{Literal, TokenStream, TokenTree}; 2 use quote::{format_ident, quote}; 3 use std::collections::HashSet; 4 use std::fmt; 5 use syn::parse::{Parse, ParseStream}; 6 use syn::punctuated::Punctuated; 7 use syn::{braced, parse_macro_input, parse_quote, Data, DeriveInput, Error, Result, Token}; 8 use wasmtime_component_util::{DiscriminantSize, FlagsSize}; 9 10 #[derive(Debug, Copy, Clone)] 11 enum VariantStyle { 12 Variant, 13 Enum, 14 Union, 15 } 16 17 impl fmt::Display for VariantStyle { 18 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { 19 f.write_str(match self { 20 Self::Variant => "variant", 21 Self::Enum => "enum", 22 Self::Union => "union", 23 }) 24 } 25 } 26 27 #[derive(Debug, Copy, Clone)] 28 enum Style { 29 Record, 30 Variant(VariantStyle), 31 } 32 33 fn find_style(input: &DeriveInput) -> Result<Style> { 34 let mut style = None; 35 36 for attribute in &input.attrs { 37 if attribute.path.leading_colon.is_some() || attribute.path.segments.len() != 1 { 38 continue; 39 } 40 41 let ident = &attribute.path.segments[0].ident; 42 43 if "component" != &ident.to_string() { 44 continue; 45 } 46 47 let syntax_error = || { 48 Err(Error::new_spanned( 49 &attribute.tokens, 50 "expected `component(<style>)` syntax", 51 )) 52 }; 53 54 let style_string = if let [TokenTree::Group(group)] = 55 &attribute.tokens.clone().into_iter().collect::<Vec<_>>()[..] 56 { 57 if let [TokenTree::Ident(style)] = &group.stream().into_iter().collect::<Vec<_>>()[..] { 58 style.to_string() 59 } else { 60 return syntax_error(); 61 } 62 } else { 63 return syntax_error(); 64 }; 65 66 if style.is_some() { 67 return Err(Error::new(ident.span(), "duplicate `component` attribute")); 68 } 69 70 style = Some(match style_string.as_ref() { 71 "record" => Style::Record, 72 "variant" => Style::Variant(VariantStyle::Variant), 73 "enum" => Style::Variant(VariantStyle::Enum), 74 "union" => Style::Variant(VariantStyle::Union), 75 "flags" => { 76 return Err(Error::new_spanned( 77 &attribute.tokens, 78 "`flags` not allowed here; \ 79 use `wasmtime::component::flags!` macro to define `flags` types", 80 )) 81 } 82 _ => { 83 return Err(Error::new_spanned( 84 &attribute.tokens, 85 "unrecognized component type keyword \ 86 (expected `record`, `variant`, `enum`, or `union`)", 87 )) 88 } 89 }); 90 } 91 92 style.ok_or_else(|| Error::new_spanned(input, "missing `component` attribute")) 93 } 94 95 fn find_rename(attributes: &[syn::Attribute]) -> Result<Option<Literal>> { 96 let mut name = None; 97 98 for attribute in attributes { 99 if attribute.path.leading_colon.is_some() || attribute.path.segments.len() != 1 { 100 continue; 101 } 102 103 let ident = &attribute.path.segments[0].ident; 104 105 if "component" != &ident.to_string() { 106 continue; 107 } 108 109 let syntax_error = || { 110 Err(Error::new_spanned( 111 &attribute.tokens, 112 "expected `component(name = <name literal>)` syntax", 113 )) 114 }; 115 116 let name_literal = if let [TokenTree::Group(group)] = 117 &attribute.tokens.clone().into_iter().collect::<Vec<_>>()[..] 118 { 119 match &group.stream().into_iter().collect::<Vec<_>>()[..] { 120 [TokenTree::Ident(key), TokenTree::Punct(op), TokenTree::Literal(literal)] 121 if "name" == &key.to_string() && '=' == op.as_char() => 122 { 123 literal.clone() 124 } 125 _ => return syntax_error(), 126 } 127 } else { 128 return syntax_error(); 129 }; 130 131 if name.is_some() { 132 return Err(Error::new(ident.span(), "duplicate field rename attribute")); 133 } 134 135 name = Some(name_literal); 136 } 137 138 Ok(name) 139 } 140 141 fn add_trait_bounds(generics: &syn::Generics, bound: syn::TypeParamBound) -> syn::Generics { 142 let mut generics = generics.clone(); 143 for param in &mut generics.params { 144 if let syn::GenericParam::Type(ref mut type_param) = *param { 145 type_param.bounds.push(bound.clone()); 146 } 147 } 148 generics 149 } 150 151 struct VariantCase<'a> { 152 attrs: &'a [syn::Attribute], 153 ident: &'a syn::Ident, 154 ty: Option<&'a syn::Type>, 155 } 156 157 trait Expander { 158 fn expand_record( 159 &self, 160 name: &syn::Ident, 161 generics: &syn::Generics, 162 fields: &[&syn::Field], 163 ) -> Result<TokenStream>; 164 165 fn expand_variant( 166 &self, 167 name: &syn::Ident, 168 generics: &syn::Generics, 169 discriminant_size: DiscriminantSize, 170 cases: &[VariantCase], 171 style: VariantStyle, 172 ) -> Result<TokenStream>; 173 } 174 175 fn expand(expander: &dyn Expander, input: &DeriveInput) -> Result<TokenStream> { 176 match find_style(input)? { 177 Style::Record => expand_record(expander, input), 178 Style::Variant(style) => expand_variant(expander, input, style), 179 } 180 } 181 182 fn expand_record(expander: &dyn Expander, input: &DeriveInput) -> Result<TokenStream> { 183 let name = &input.ident; 184 185 let body = if let Data::Struct(body) = &input.data { 186 body 187 } else { 188 return Err(Error::new( 189 name.span(), 190 "`record` component types can only be derived for Rust `struct`s", 191 )); 192 }; 193 194 match &body.fields { 195 syn::Fields::Named(fields) => expander.expand_record( 196 &input.ident, 197 &input.generics, 198 &fields.named.iter().collect::<Vec<_>>(), 199 ), 200 201 syn::Fields::Unnamed(_) | syn::Fields::Unit => Err(Error::new( 202 name.span(), 203 "`record` component types can only be derived for `struct`s with named fields", 204 )), 205 } 206 } 207 208 fn expand_variant( 209 expander: &dyn Expander, 210 input: &DeriveInput, 211 style: VariantStyle, 212 ) -> Result<TokenStream> { 213 let name = &input.ident; 214 215 let body = if let Data::Enum(body) = &input.data { 216 body 217 } else { 218 return Err(Error::new( 219 name.span(), 220 format!( 221 "`{}` component types can only be derived for Rust `enum`s", 222 style 223 ), 224 )); 225 }; 226 227 if body.variants.is_empty() { 228 return Err(Error::new( 229 name.span(), 230 format!("`{}` component types can only be derived for Rust `enum`s with at least one variant", style), 231 )); 232 } 233 234 let discriminant_size = DiscriminantSize::from_count(body.variants.len()).ok_or_else(|| { 235 Error::new( 236 input.ident.span(), 237 "`enum`s with more than 2^32 variants are not supported", 238 ) 239 })?; 240 241 let cases = body 242 .variants 243 .iter() 244 .map( 245 |syn::Variant { 246 attrs, 247 ident, 248 fields, 249 .. 250 }| { 251 Ok(VariantCase { 252 attrs, 253 ident, 254 ty: match fields { 255 syn::Fields::Unnamed(fields) if fields.unnamed.len() == 1 => { 256 Some(&fields.unnamed[0].ty) 257 } 258 syn::Fields::Unit => None, 259 _ => { 260 return Err(Error::new( 261 name.span(), 262 format!( 263 "`{}` component types can only be derived for Rust `enum`s \ 264 containing variants with {}", 265 style, 266 match style { 267 VariantStyle::Variant => "at most one unnamed field each", 268 VariantStyle::Enum => "no fields", 269 VariantStyle::Union => "exactly one unnamed field each", 270 } 271 ), 272 )) 273 } 274 }, 275 }) 276 }, 277 ) 278 .collect::<Result<Vec<_>>>()?; 279 280 expander.expand_variant( 281 &input.ident, 282 &input.generics, 283 discriminant_size, 284 &cases, 285 style, 286 ) 287 } 288 289 fn expand_record_for_component_type( 290 name: &syn::Ident, 291 generics: &syn::Generics, 292 fields: &[&syn::Field], 293 typecheck: TokenStream, 294 typecheck_argument: TokenStream, 295 ) -> Result<TokenStream> { 296 let internal = quote!(wasmtime::component::__internal); 297 298 let mut lower_generic_params = TokenStream::new(); 299 let mut lower_generic_args = TokenStream::new(); 300 let mut lower_field_declarations = TokenStream::new(); 301 let mut abi_list = TokenStream::new(); 302 let mut unique_types = HashSet::new(); 303 304 for (index, syn::Field { ident, ty, .. }) in fields.iter().enumerate() { 305 let generic = format_ident!("T{}", index); 306 307 lower_generic_params.extend(quote!(#generic: Copy,)); 308 lower_generic_args.extend(quote!(<#ty as wasmtime::component::ComponentType>::Lower,)); 309 310 lower_field_declarations.extend(quote!(#ident: #generic,)); 311 312 abi_list.extend(quote!( 313 <#ty as wasmtime::component::ComponentType>::ABI, 314 )); 315 316 unique_types.insert(ty); 317 } 318 319 let generics = add_trait_bounds(generics, parse_quote!(wasmtime::component::ComponentType)); 320 let (impl_generics, ty_generics, where_clause) = generics.split_for_impl(); 321 let lower = format_ident!("Lower{}", name); 322 323 // You may wonder why we make the types of all the fields of the #lower struct generic. This is to work 324 // around the lack of [perfect derive support in 325 // rustc](https://smallcultfollowing.com/babysteps//blog/2022/04/12/implied-bounds-and-perfect-derive/#what-is-perfect-derive) 326 // as of this writing. 327 // 328 // If the struct we're deriving a `ComponentType` impl for has any generic parameters, then #lower needs 329 // generic parameters too. And if we just copy the parameters and bounds from the impl to #lower, then the 330 // `#[derive(Clone, Copy)]` will fail unless the original generics were declared with those bounds, which 331 // we don't want to require. 332 // 333 // Alternatively, we could just pass the `Lower` associated type of each generic type as arguments to 334 // #lower, but that would require distinguishing between generic and concrete types when generating 335 // #lower_field_declarations, which would require some form of symbol resolution. That doesn't seem worth 336 // the trouble. 337 338 let expanded = quote! { 339 #[doc(hidden)] 340 #[derive(Clone, Copy)] 341 #[repr(C)] 342 pub struct #lower <#lower_generic_params> { 343 #lower_field_declarations 344 _align: [wasmtime::ValRaw; 0], 345 } 346 347 unsafe impl #impl_generics wasmtime::component::ComponentType for #name #ty_generics #where_clause { 348 type Lower = #lower <#lower_generic_args>; 349 350 const ABI: #internal::CanonicalAbiInfo = 351 #internal::CanonicalAbiInfo::record_static(&[#abi_list]); 352 353 #[inline] 354 fn typecheck( 355 ty: &#internal::InterfaceType, 356 types: &#internal::ComponentTypes, 357 ) -> #internal::anyhow::Result<()> { 358 #internal::#typecheck(ty, types, &[#typecheck_argument]) 359 } 360 } 361 }; 362 363 Ok(quote!(const _: () = { #expanded };)) 364 } 365 366 fn quote(size: DiscriminantSize, discriminant: usize) -> TokenStream { 367 match size { 368 DiscriminantSize::Size1 => { 369 let discriminant = u8::try_from(discriminant).unwrap(); 370 quote!(#discriminant) 371 } 372 DiscriminantSize::Size2 => { 373 let discriminant = u16::try_from(discriminant).unwrap(); 374 quote!(#discriminant) 375 } 376 DiscriminantSize::Size4 => { 377 let discriminant = u32::try_from(discriminant).unwrap(); 378 quote!(#discriminant) 379 } 380 } 381 } 382 383 #[proc_macro_derive(Lift, attributes(component))] 384 pub fn lift(input: proc_macro::TokenStream) -> proc_macro::TokenStream { 385 expand(&LiftExpander, &parse_macro_input!(input as DeriveInput)) 386 .unwrap_or_else(Error::into_compile_error) 387 .into() 388 } 389 390 struct LiftExpander; 391 392 impl Expander for LiftExpander { 393 fn expand_record( 394 &self, 395 name: &syn::Ident, 396 generics: &syn::Generics, 397 fields: &[&syn::Field], 398 ) -> Result<TokenStream> { 399 let internal = quote!(wasmtime::component::__internal); 400 401 let mut lifts = TokenStream::new(); 402 let mut loads = TokenStream::new(); 403 404 for syn::Field { ident, ty, .. } in fields { 405 lifts.extend(quote!(#ident: <#ty as wasmtime::component::Lift>::lift( 406 store, options, &src.#ident 407 )?,)); 408 409 loads.extend(quote!(#ident: <#ty as wasmtime::component::Lift>::load( 410 memory, 411 &bytes 412 [<#ty as wasmtime::component::ComponentType>::ABI.next_field32_size(&mut offset)..] 413 [..<#ty as wasmtime::component::ComponentType>::SIZE32] 414 )?,)); 415 } 416 417 let generics = add_trait_bounds(generics, parse_quote!(wasmtime::component::Lift)); 418 let (impl_generics, ty_generics, where_clause) = generics.split_for_impl(); 419 420 let expanded = quote! { 421 unsafe impl #impl_generics wasmtime::component::Lift for #name #ty_generics #where_clause { 422 #[inline] 423 fn lift( 424 store: &#internal::StoreOpaque, 425 options: &#internal::Options, 426 src: &Self::Lower, 427 ) -> #internal::anyhow::Result<Self> { 428 Ok(Self { 429 #lifts 430 }) 431 } 432 433 #[inline] 434 fn load(memory: &#internal::Memory, bytes: &[u8]) -> #internal::anyhow::Result<Self> { 435 debug_assert!( 436 (bytes.as_ptr() as usize) 437 % (<Self as wasmtime::component::ComponentType>::ALIGN32 as usize) 438 == 0 439 ); 440 let mut offset = 0; 441 Ok(Self { 442 #loads 443 }) 444 } 445 } 446 }; 447 448 Ok(expanded) 449 } 450 451 fn expand_variant( 452 &self, 453 name: &syn::Ident, 454 generics: &syn::Generics, 455 discriminant_size: DiscriminantSize, 456 cases: &[VariantCase], 457 _style: VariantStyle, 458 ) -> Result<TokenStream> { 459 let internal = quote!(wasmtime::component::__internal); 460 461 let mut lifts = TokenStream::new(); 462 let mut loads = TokenStream::new(); 463 464 for (index, VariantCase { ident, ty, .. }) in cases.iter().enumerate() { 465 let index_u32 = u32::try_from(index).unwrap(); 466 467 let index_quoted = quote(discriminant_size, index); 468 469 if let Some(ty) = ty { 470 lifts.extend( 471 quote!(#index_u32 => Self::#ident(<#ty as wasmtime::component::Lift>::lift( 472 store, options, unsafe { &src.payload.#ident } 473 )?),), 474 ); 475 476 loads.extend( 477 quote!(#index_quoted => Self::#ident(<#ty as wasmtime::component::Lift>::load( 478 memory, &payload[..<#ty as wasmtime::component::ComponentType>::SIZE32] 479 )?),), 480 ); 481 } else { 482 lifts.extend(quote!(#index_u32 => Self::#ident,)); 483 484 loads.extend(quote!(#index_quoted => Self::#ident,)); 485 } 486 } 487 488 let generics = add_trait_bounds(generics, parse_quote!(wasmtime::component::Lift)); 489 let (impl_generics, ty_generics, where_clause) = generics.split_for_impl(); 490 491 let from_bytes = match discriminant_size { 492 DiscriminantSize::Size1 => quote!(bytes[0]), 493 DiscriminantSize::Size2 => quote!(u16::from_le_bytes(bytes[0..2].try_into()?)), 494 DiscriminantSize::Size4 => quote!(u32::from_le_bytes(bytes[0..4].try_into()?)), 495 }; 496 497 let expanded = quote! { 498 unsafe impl #impl_generics wasmtime::component::Lift for #name #ty_generics #where_clause { 499 #[inline] 500 fn lift( 501 store: &#internal::StoreOpaque, 502 options: &#internal::Options, 503 src: &Self::Lower, 504 ) -> #internal::anyhow::Result<Self> { 505 Ok(match src.tag.get_u32() { 506 #lifts 507 discrim => #internal::anyhow::bail!("unexpected discriminant: {}", discrim), 508 }) 509 } 510 511 #[inline] 512 fn load(memory: &#internal::Memory, bytes: &[u8]) -> #internal::anyhow::Result<Self> { 513 let align = <Self as wasmtime::component::ComponentType>::ALIGN32; 514 debug_assert!((bytes.as_ptr() as usize) % (align as usize) == 0); 515 let discrim = #from_bytes; 516 let payload_offset = <Self as #internal::ComponentVariant>::PAYLOAD_OFFSET32; 517 let payload = &bytes[payload_offset..]; 518 Ok(match discrim { 519 #loads 520 discrim => #internal::anyhow::bail!("unexpected discriminant: {}", discrim), 521 }) 522 } 523 } 524 }; 525 526 Ok(expanded) 527 } 528 } 529 530 #[proc_macro_derive(Lower, attributes(component))] 531 pub fn lower(input: proc_macro::TokenStream) -> proc_macro::TokenStream { 532 expand(&LowerExpander, &parse_macro_input!(input as DeriveInput)) 533 .unwrap_or_else(Error::into_compile_error) 534 .into() 535 } 536 537 struct LowerExpander; 538 539 impl Expander for LowerExpander { 540 fn expand_record( 541 &self, 542 name: &syn::Ident, 543 generics: &syn::Generics, 544 fields: &[&syn::Field], 545 ) -> Result<TokenStream> { 546 let internal = quote!(wasmtime::component::__internal); 547 548 let mut lowers = TokenStream::new(); 549 let mut stores = TokenStream::new(); 550 551 for syn::Field { ident, ty, .. } in fields { 552 lowers.extend(quote!(wasmtime::component::Lower::lower( 553 &self.#ident, store, options, #internal::map_maybe_uninit!(dst.#ident) 554 )?;)); 555 556 stores.extend(quote!(wasmtime::component::Lower::store( 557 &self.#ident, 558 memory, 559 <#ty as wasmtime::component::ComponentType>::ABI.next_field32_size(&mut offset), 560 )?;)); 561 } 562 563 let generics = add_trait_bounds(generics, parse_quote!(wasmtime::component::Lower)); 564 let (impl_generics, ty_generics, where_clause) = generics.split_for_impl(); 565 566 let expanded = quote! { 567 unsafe impl #impl_generics wasmtime::component::Lower for #name #ty_generics #where_clause { 568 #[inline] 569 fn lower<T>( 570 &self, 571 store: &mut wasmtime::StoreContextMut<T>, 572 options: &#internal::Options, 573 dst: &mut std::mem::MaybeUninit<Self::Lower>, 574 ) -> #internal::anyhow::Result<()> { 575 #lowers 576 Ok(()) 577 } 578 579 #[inline] 580 fn store<T>( 581 &self, 582 memory: &mut #internal::MemoryMut<'_, T>, 583 mut offset: usize 584 ) -> #internal::anyhow::Result<()> { 585 debug_assert!(offset % (<Self as wasmtime::component::ComponentType>::ALIGN32 as usize) == 0); 586 #stores 587 Ok(()) 588 } 589 } 590 }; 591 592 Ok(expanded) 593 } 594 595 fn expand_variant( 596 &self, 597 name: &syn::Ident, 598 generics: &syn::Generics, 599 discriminant_size: DiscriminantSize, 600 cases: &[VariantCase], 601 _style: VariantStyle, 602 ) -> Result<TokenStream> { 603 let internal = quote!(wasmtime::component::__internal); 604 605 let mut lowers = TokenStream::new(); 606 let mut stores = TokenStream::new(); 607 608 for (index, VariantCase { ident, ty, .. }) in cases.iter().enumerate() { 609 let index_u32 = u32::try_from(index).unwrap(); 610 611 let index_quoted = quote(discriminant_size, index); 612 613 let discriminant_size = usize::from(discriminant_size); 614 615 let pattern; 616 let lower; 617 let store; 618 619 if ty.is_some() { 620 pattern = quote!(Self::#ident(value)); 621 lower = quote!(value.lower(store, options, dst)); 622 store = quote!(value.store( 623 memory, 624 offset + <Self as #internal::ComponentVariant>::PAYLOAD_OFFSET32, 625 )); 626 } else { 627 pattern = quote!(Self::#ident); 628 lower = quote!(Ok(())); 629 store = quote!(Ok(())); 630 } 631 632 lowers.extend(quote!(#pattern => { 633 #internal::map_maybe_uninit!(dst.tag).write(wasmtime::ValRaw::u32(#index_u32)); 634 unsafe { 635 #internal::lower_payload( 636 #internal::map_maybe_uninit!(dst.payload), 637 |payload| #internal::map_maybe_uninit!(payload.#ident), 638 |dst| #lower, 639 ) 640 } 641 })); 642 643 stores.extend(quote!(#pattern => { 644 *memory.get::<#discriminant_size>(offset) = #index_quoted.to_le_bytes(); 645 #store 646 })); 647 } 648 649 let generics = add_trait_bounds(generics, parse_quote!(wasmtime::component::Lower)); 650 let (impl_generics, ty_generics, where_clause) = generics.split_for_impl(); 651 652 let expanded = quote! { 653 unsafe impl #impl_generics wasmtime::component::Lower for #name #ty_generics #where_clause { 654 #[inline] 655 fn lower<T>( 656 &self, 657 store: &mut wasmtime::StoreContextMut<T>, 658 options: &#internal::Options, 659 dst: &mut std::mem::MaybeUninit<Self::Lower>, 660 ) -> #internal::anyhow::Result<()> { 661 match self { 662 #lowers 663 } 664 } 665 666 #[inline] 667 fn store<T>( 668 &self, 669 memory: &mut #internal::MemoryMut<'_, T>, 670 mut offset: usize 671 ) -> #internal::anyhow::Result<()> { 672 debug_assert!(offset % (<Self as wasmtime::component::ComponentType>::ALIGN32 as usize) == 0); 673 match self { 674 #stores 675 } 676 } 677 } 678 }; 679 680 Ok(expanded) 681 } 682 } 683 684 #[proc_macro_derive(ComponentType, attributes(component))] 685 pub fn component_type(input: proc_macro::TokenStream) -> proc_macro::TokenStream { 686 expand( 687 &ComponentTypeExpander, 688 &parse_macro_input!(input as DeriveInput), 689 ) 690 .unwrap_or_else(Error::into_compile_error) 691 .into() 692 } 693 694 struct ComponentTypeExpander; 695 696 impl Expander for ComponentTypeExpander { 697 fn expand_record( 698 &self, 699 name: &syn::Ident, 700 generics: &syn::Generics, 701 fields: &[&syn::Field], 702 ) -> Result<TokenStream> { 703 expand_record_for_component_type( 704 name, 705 generics, 706 fields, 707 quote!(typecheck_record), 708 fields 709 .iter() 710 .map( 711 |syn::Field { 712 attrs, ident, ty, .. 713 }| { 714 let name = find_rename(attrs)?.unwrap_or_else(|| { 715 Literal::string(&ident.as_ref().unwrap().to_string()) 716 }); 717 718 Ok(quote!((#name, <#ty as wasmtime::component::ComponentType>::typecheck),)) 719 }, 720 ) 721 .collect::<Result<_>>()?, 722 ) 723 } 724 725 fn expand_variant( 726 &self, 727 name: &syn::Ident, 728 generics: &syn::Generics, 729 _discriminant_size: DiscriminantSize, 730 cases: &[VariantCase], 731 style: VariantStyle, 732 ) -> Result<TokenStream> { 733 let internal = quote!(wasmtime::component::__internal); 734 735 let mut case_names_and_checks = TokenStream::new(); 736 let mut lower_payload_generic_params = TokenStream::new(); 737 let mut lower_payload_generic_args = TokenStream::new(); 738 let mut lower_payload_case_declarations = TokenStream::new(); 739 let mut lower_generic_args = TokenStream::new(); 740 let mut abi_list = TokenStream::new(); 741 let mut unique_types = HashSet::new(); 742 743 for (index, VariantCase { attrs, ident, ty }) in cases.iter().enumerate() { 744 let rename = find_rename(attrs)?; 745 746 if let (Some(_), VariantStyle::Union) = (&rename, style) { 747 return Err(Error::new( 748 ident.span(), 749 "renaming `union` cases is not permitted; only the type is used", 750 )); 751 } 752 753 let name = rename.unwrap_or_else(|| Literal::string(&ident.to_string())); 754 755 if let Some(ty) = ty { 756 abi_list.extend(quote!(Some(<#ty as wasmtime::component::ComponentType>::ABI),)); 757 758 case_names_and_checks.extend(match style { 759 VariantStyle::Variant => { 760 quote!((#name, Some(<#ty as wasmtime::component::ComponentType>::typecheck)),) 761 } 762 VariantStyle::Union => { 763 quote!(<#ty as wasmtime::component::ComponentType>::typecheck,) 764 } 765 VariantStyle::Enum => { 766 return Err(Error::new( 767 ident.span(), 768 "payloads are not permitted for `enum` cases", 769 )) 770 } 771 }); 772 773 let generic = format_ident!("T{}", index); 774 775 lower_payload_generic_params.extend(quote!(#generic: Copy,)); 776 lower_payload_generic_args.extend(quote!(#generic,)); 777 lower_payload_case_declarations.extend(quote!(#ident: #generic,)); 778 lower_generic_args 779 .extend(quote!(<#ty as wasmtime::component::ComponentType>::Lower,)); 780 781 unique_types.insert(ty); 782 } else { 783 abi_list.extend(quote!(None,)); 784 case_names_and_checks.extend(match style { 785 VariantStyle::Variant => { 786 quote!((#name, None),) 787 } 788 VariantStyle::Union => { 789 quote!(<() as wasmtime::component::ComponentType>::typecheck,) 790 } 791 VariantStyle::Enum => quote!(#name,), 792 }); 793 lower_payload_case_declarations.extend(quote!(#ident: [wasmtime::ValRaw; 0],)); 794 } 795 } 796 797 let typecheck = match style { 798 VariantStyle::Variant => quote!(typecheck_variant), 799 VariantStyle::Union => quote!(typecheck_union), 800 VariantStyle::Enum => quote!(typecheck_enum), 801 }; 802 803 let generics = add_trait_bounds(generics, parse_quote!(wasmtime::component::ComponentType)); 804 let (impl_generics, ty_generics, where_clause) = generics.split_for_impl(); 805 let lower = format_ident!("Lower{}", name); 806 let lower_payload = format_ident!("LowerPayload{}", name); 807 808 // You may wonder why we make the types of all the fields of the #lower struct and #lower_payload union 809 // generic. This is to work around a [normalization bug in 810 // rustc](https://github.com/rust-lang/rust/issues/90903) such that the compiler does not understand that 811 // e.g. `<i32 as ComponentType>::Lower` is `Copy` despite the bound specified in `ComponentType`'s 812 // definition. 813 // 814 // See also the comment in `Self::expand_record` above for another reason why we do this. 815 816 let expanded = quote! { 817 #[doc(hidden)] 818 #[derive(Clone, Copy)] 819 #[repr(C)] 820 pub struct #lower<#lower_payload_generic_params> { 821 tag: wasmtime::ValRaw, 822 payload: #lower_payload<#lower_payload_generic_args> 823 } 824 825 #[doc(hidden)] 826 #[allow(non_snake_case)] 827 #[derive(Clone, Copy)] 828 #[repr(C)] 829 union #lower_payload<#lower_payload_generic_params> { 830 #lower_payload_case_declarations 831 } 832 833 unsafe impl #impl_generics wasmtime::component::ComponentType for #name #ty_generics #where_clause { 834 type Lower = #lower<#lower_generic_args>; 835 836 #[inline] 837 fn typecheck( 838 ty: &#internal::InterfaceType, 839 types: &#internal::ComponentTypes, 840 ) -> #internal::anyhow::Result<()> { 841 #internal::#typecheck(ty, types, &[#case_names_and_checks]) 842 } 843 844 const ABI: #internal::CanonicalAbiInfo = 845 #internal::CanonicalAbiInfo::variant_static(&[#abi_list]); 846 } 847 848 unsafe impl #impl_generics #internal::ComponentVariant for #name #ty_generics #where_clause { 849 const CASES: &'static [Option<#internal::CanonicalAbiInfo>] = &[#abi_list]; 850 } 851 }; 852 853 Ok(quote!(const _: () = { #expanded };)) 854 } 855 } 856 857 #[derive(Debug)] 858 struct Flag { 859 rename: Option<String>, 860 name: String, 861 } 862 863 impl Parse for Flag { 864 fn parse(input: ParseStream) -> Result<Self> { 865 let attributes = syn::Attribute::parse_outer(input)?; 866 867 let rename = find_rename(&attributes)? 868 .map(|literal| { 869 let s = literal.to_string(); 870 871 s.strip_prefix('"') 872 .and_then(|s| s.strip_suffix('"')) 873 .map(|s| s.to_owned()) 874 .ok_or_else(|| Error::new(literal.span(), "expected string literal")) 875 }) 876 .transpose()?; 877 878 input.parse::<Token![const]>()?; 879 let name = input.parse::<syn::Ident>()?.to_string(); 880 881 Ok(Self { rename, name }) 882 } 883 } 884 885 #[derive(Debug)] 886 struct Flags { 887 name: String, 888 flags: Vec<Flag>, 889 } 890 891 impl Parse for Flags { 892 fn parse(input: ParseStream) -> Result<Self> { 893 let name = input.parse::<syn::Ident>()?.to_string(); 894 895 let content; 896 braced!(content in input); 897 898 let flags = content 899 .parse_terminated::<_, Token![;]>(Flag::parse)? 900 .into_iter() 901 .collect(); 902 903 Ok(Self { name, flags }) 904 } 905 } 906 907 #[proc_macro] 908 pub fn flags(input: proc_macro::TokenStream) -> proc_macro::TokenStream { 909 expand_flags(&parse_macro_input!(input as Flags)) 910 .unwrap_or_else(Error::into_compile_error) 911 .into() 912 } 913 914 fn expand_flags(flags: &Flags) -> Result<TokenStream> { 915 let size = FlagsSize::from_count(flags.flags.len()); 916 917 let ty; 918 let eq; 919 920 let count = flags.flags.len(); 921 922 match size { 923 FlagsSize::Size0 => { 924 ty = quote!(()); 925 eq = quote!(true); 926 } 927 FlagsSize::Size1 => { 928 ty = quote!(u8); 929 930 eq = if count == 8 { 931 quote!(self.__inner0.eq(&rhs.__inner0)) 932 } else { 933 let mask = !(0xFF_u8 << count); 934 935 quote!((self.__inner0 & #mask).eq(&(rhs.__inner0 & #mask))) 936 }; 937 } 938 FlagsSize::Size2 => { 939 ty = quote!(u16); 940 941 eq = if count == 16 { 942 quote!(self.__inner0.eq(&rhs.__inner0)) 943 } else { 944 let mask = !(0xFFFF_u16 << count); 945 946 quote!((self.__inner0 & #mask).eq(&(rhs.__inner0 & #mask))) 947 }; 948 } 949 FlagsSize::Size4Plus(n) => { 950 ty = quote!(u32); 951 952 let comparisons = (0..(n - 1)) 953 .map(|index| { 954 let field = format_ident!("__inner{}", index); 955 956 quote!(self.#field.eq(&rhs.#field) &&) 957 }) 958 .collect::<TokenStream>(); 959 960 let field = format_ident!("__inner{}", n - 1); 961 962 eq = if count % 32 == 0 { 963 quote!(#comparisons self.#field.eq(&rhs.#field)) 964 } else { 965 let mask = !(0xFFFF_FFFF_u32 << (count % 32)); 966 967 quote!(#comparisons (self.#field & #mask).eq(&(rhs.#field & #mask))) 968 } 969 } 970 } 971 972 let count; 973 let mut as_array; 974 let mut bitor; 975 let mut bitor_assign; 976 let mut bitand; 977 let mut bitand_assign; 978 let mut bitxor; 979 let mut bitxor_assign; 980 let mut not; 981 982 match size { 983 FlagsSize::Size0 => { 984 count = 0; 985 as_array = quote!([]); 986 bitor = quote!(Self {}); 987 bitor_assign = quote!(); 988 bitand = quote!(Self {}); 989 bitand_assign = quote!(); 990 bitxor = quote!(Self {}); 991 bitxor_assign = quote!(); 992 not = quote!(Self {}); 993 } 994 FlagsSize::Size1 | FlagsSize::Size2 => { 995 count = 1; 996 as_array = quote!([self.__inner0 as u32]); 997 bitor = quote!(Self { 998 __inner0: self.__inner0.bitor(rhs.__inner0) 999 }); 1000 bitor_assign = quote!(self.__inner0.bitor_assign(rhs.__inner0)); 1001 bitand = quote!(Self { 1002 __inner0: self.__inner0.bitand(rhs.__inner0) 1003 }); 1004 bitand_assign = quote!(self.__inner0.bitand_assign(rhs.__inner0)); 1005 bitxor = quote!(Self { 1006 __inner0: self.__inner0.bitxor(rhs.__inner0) 1007 }); 1008 bitxor_assign = quote!(self.__inner0.bitxor_assign(rhs.__inner0)); 1009 not = quote!(Self { 1010 __inner0: self.__inner0.not() 1011 }); 1012 } 1013 FlagsSize::Size4Plus(n) => { 1014 count = usize::from(n); 1015 as_array = TokenStream::new(); 1016 bitor = TokenStream::new(); 1017 bitor_assign = TokenStream::new(); 1018 bitand = TokenStream::new(); 1019 bitand_assign = TokenStream::new(); 1020 bitxor = TokenStream::new(); 1021 bitxor_assign = TokenStream::new(); 1022 not = TokenStream::new(); 1023 1024 for index in 0..n { 1025 let field = format_ident!("__inner{}", index); 1026 1027 as_array.extend(quote!(self.#field,)); 1028 bitor.extend(quote!(#field: self.#field.bitor(rhs.#field),)); 1029 bitor_assign.extend(quote!(self.#field.bitor_assign(rhs.#field);)); 1030 bitand.extend(quote!(#field: self.#field.bitand(rhs.#field),)); 1031 bitand_assign.extend(quote!(self.#field.bitand_assign(rhs.#field);)); 1032 bitxor.extend(quote!(#field: self.#field.bitxor(rhs.#field),)); 1033 bitxor_assign.extend(quote!(self.#field.bitxor_assign(rhs.#field);)); 1034 not.extend(quote!(#field: self.#field.not(),)); 1035 } 1036 1037 as_array = quote!([#as_array]); 1038 bitor = quote!(Self { #bitor }); 1039 bitand = quote!(Self { #bitand }); 1040 bitxor = quote!(Self { #bitxor }); 1041 not = quote!(Self { #not }); 1042 } 1043 }; 1044 1045 let name = format_ident!("{}", flags.name); 1046 1047 let mut constants = TokenStream::new(); 1048 let mut rust_names = TokenStream::new(); 1049 let mut component_names = TokenStream::new(); 1050 1051 for (index, Flag { name, rename }) in flags.flags.iter().enumerate() { 1052 rust_names.extend(quote!(#name,)); 1053 1054 let component_name = rename.as_ref().unwrap_or(name); 1055 component_names.extend(quote!(#component_name,)); 1056 1057 let fields = match size { 1058 FlagsSize::Size0 => quote!(), 1059 FlagsSize::Size1 => { 1060 let init = 1_u8 << index; 1061 quote!(__inner0: #init) 1062 } 1063 FlagsSize::Size2 => { 1064 let init = 1_u16 << index; 1065 quote!(__inner0: #init) 1066 } 1067 FlagsSize::Size4Plus(n) => (0..n) 1068 .map(|i| { 1069 let field = format_ident!("__inner{}", i); 1070 1071 let init = if index / 32 == usize::from(i) { 1072 1_u32 << (index % 32) 1073 } else { 1074 0 1075 }; 1076 1077 quote!(#field: #init,) 1078 }) 1079 .collect::<TokenStream>(), 1080 }; 1081 1082 let name = format_ident!("{}", name); 1083 1084 constants.extend(quote!(const #name: Self = Self { #fields };)); 1085 } 1086 1087 let generics = syn::Generics { 1088 lt_token: None, 1089 params: Punctuated::new(), 1090 gt_token: None, 1091 where_clause: None, 1092 }; 1093 1094 let fields = { 1095 let ty = syn::parse2::<syn::Type>(ty.clone())?; 1096 1097 (0..count) 1098 .map(|index| syn::Field { 1099 attrs: Vec::new(), 1100 vis: syn::Visibility::Inherited, 1101 ident: Some(format_ident!("__inner{}", index)), 1102 colon_token: None, 1103 ty: ty.clone(), 1104 }) 1105 .collect::<Vec<_>>() 1106 }; 1107 1108 let fields = fields.iter().collect::<Vec<_>>(); 1109 1110 let component_type_impl = expand_record_for_component_type( 1111 &name, 1112 &generics, 1113 &fields, 1114 quote!(typecheck_flags), 1115 component_names, 1116 )?; 1117 1118 let lower_impl = LowerExpander.expand_record(&name, &generics, &fields)?; 1119 1120 let lift_impl = LiftExpander.expand_record(&name, &generics, &fields)?; 1121 1122 let internal = quote!(wasmtime::component::__internal); 1123 1124 let fields = fields 1125 .iter() 1126 .map(|syn::Field { ident, .. }| quote!(#[doc(hidden)] #ident: #ty,)) 1127 .collect::<TokenStream>(); 1128 1129 let expanded = quote! { 1130 #[derive(Copy, Clone, Default)] 1131 struct #name { #fields } 1132 1133 impl #name { 1134 #constants 1135 1136 fn as_array(&self) -> [u32; #count] { 1137 #as_array 1138 } 1139 } 1140 1141 impl std::cmp::PartialEq for #name { 1142 fn eq(&self, rhs: &#name) -> bool { 1143 #eq 1144 } 1145 } 1146 1147 impl std::cmp::Eq for #name { } 1148 1149 impl std::fmt::Debug for #name { 1150 fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result { 1151 #internal::format_flags(&self.as_array(), &[#rust_names], f) 1152 } 1153 } 1154 1155 impl std::ops::BitOr for #name { 1156 type Output = #name; 1157 1158 fn bitor(self, rhs: #name) -> #name { 1159 #bitor 1160 } 1161 } 1162 1163 impl std::ops::BitOrAssign for #name { 1164 fn bitor_assign(&mut self, rhs: #name) { 1165 #bitor_assign 1166 } 1167 } 1168 1169 impl std::ops::BitAnd for #name { 1170 type Output = #name; 1171 1172 fn bitand(self, rhs: #name) -> #name { 1173 #bitand 1174 } 1175 } 1176 1177 impl std::ops::BitAndAssign for #name { 1178 fn bitand_assign(&mut self, rhs: #name) { 1179 #bitand_assign 1180 } 1181 } 1182 1183 impl std::ops::BitXor for #name { 1184 type Output = #name; 1185 1186 fn bitxor(self, rhs: #name) -> #name { 1187 #bitxor 1188 } 1189 } 1190 1191 impl std::ops::BitXorAssign for #name { 1192 fn bitxor_assign(&mut self, rhs: #name) { 1193 #bitxor_assign 1194 } 1195 } 1196 1197 impl std::ops::Not for #name { 1198 type Output = #name; 1199 1200 fn not(self) -> #name { 1201 #not 1202 } 1203 } 1204 1205 #component_type_impl 1206 1207 #lower_impl 1208 1209 #lift_impl 1210 }; 1211 1212 Ok(expanded) 1213 } 1214