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| 1 | +use crate::reducer::{assert_only_lifetime_generics, extract_typed_args}; |
| 2 | +use crate::sym; |
| 3 | +use crate::util::{check_duplicate, ident_to_litstr, match_meta}; |
| 4 | +use proc_macro2::TokenStream; |
| 5 | +use quote::quote; |
| 6 | +use syn::parse::Parser as _; |
| 7 | +use syn::{ItemFn, LitStr}; |
| 8 | + |
| 9 | +#[derive(Default)] |
| 10 | +pub(crate) struct ProcedureArgs { |
| 11 | + /// For consistency with reducers: allow specifying a different export name than the Rust function name. |
| 12 | + name: Option<LitStr>, |
| 13 | +} |
| 14 | + |
| 15 | +impl ProcedureArgs { |
| 16 | + pub(crate) fn parse(input: TokenStream) -> syn::Result<Self> { |
| 17 | + let mut args = Self::default(); |
| 18 | + syn::meta::parser(|meta| { |
| 19 | + match_meta!(match meta { |
| 20 | + sym::name => { |
| 21 | + check_duplicate(&args.name, &meta)?; |
| 22 | + args.name = Some(meta.value()?.parse()?); |
| 23 | + } |
| 24 | + }); |
| 25 | + Ok(()) |
| 26 | + }) |
| 27 | + .parse2(input)?; |
| 28 | + Ok(args) |
| 29 | + } |
| 30 | +} |
| 31 | + |
| 32 | +pub(crate) fn procedure_impl(args: ProcedureArgs, original_function: &ItemFn) -> syn::Result<TokenStream> { |
| 33 | + let func_name = &original_function.sig.ident; |
| 34 | + let vis = &original_function.vis; |
| 35 | + |
| 36 | + let procedure_name = args.name.unwrap_or_else(|| ident_to_litstr(func_name)); |
| 37 | + |
| 38 | + assert_only_lifetime_generics(original_function, "procedures")?; |
| 39 | + |
| 40 | + let typed_args = extract_typed_args(original_function)?; |
| 41 | + |
| 42 | + // TODO: Require that procedures be `async` functions syntactically, |
| 43 | + // and use `futures_util::FutureExt::now_or_never` to poll them. |
| 44 | + // if !&original_function.sig.asyncness.is_some() { |
| 45 | + // return Err(syn::Error::new_spanned( |
| 46 | + // original_function.sig.clone(), |
| 47 | + // "procedures must be `async`", |
| 48 | + // )); |
| 49 | + // }; |
| 50 | + |
| 51 | + // Extract all function parameter names. |
| 52 | + let opt_arg_names = typed_args.iter().map(|arg| { |
| 53 | + if let syn::Pat::Ident(i) = &*arg.pat { |
| 54 | + let name = i.ident.to_string(); |
| 55 | + quote!(Some(#name)) |
| 56 | + } else { |
| 57 | + quote!(None) |
| 58 | + } |
| 59 | + }); |
| 60 | + |
| 61 | + let arg_tys = typed_args.iter().map(|arg| arg.ty.as_ref()).collect::<Vec<_>>(); |
| 62 | + let first_arg_ty = arg_tys.first().into_iter(); |
| 63 | + let rest_arg_tys = arg_tys.iter().skip(1); |
| 64 | + |
| 65 | + // Extract the return type. |
| 66 | + let ret_ty_for_assert = match &original_function.sig.output { |
| 67 | + syn::ReturnType::Default => None, |
| 68 | + syn::ReturnType::Type(_, t) => Some(&**t), |
| 69 | + } |
| 70 | + .into_iter(); |
| 71 | + |
| 72 | + let ret_ty_for_info = match &original_function.sig.output { |
| 73 | + syn::ReturnType::Default => quote!(()), |
| 74 | + syn::ReturnType::Type(_, t) => quote!(#t), |
| 75 | + }; |
| 76 | + |
| 77 | + let register_describer_symbol = format!("__preinit__20_register_describer_{}", procedure_name.value()); |
| 78 | + |
| 79 | + let lifetime_params = &original_function.sig.generics; |
| 80 | + let lifetime_where_clause = &lifetime_params.where_clause; |
| 81 | + |
| 82 | + let generated_describe_function = quote! { |
| 83 | + #[export_name = #register_describer_symbol] |
| 84 | + pub extern "C" fn __register_describer() { |
| 85 | + spacetimedb::rt::register_procedure::<_, _, #func_name>(#func_name) |
| 86 | + } |
| 87 | + }; |
| 88 | + |
| 89 | + Ok(quote! { |
| 90 | + const _: () = { |
| 91 | + #generated_describe_function |
| 92 | + }; |
| 93 | + #[allow(non_camel_case_types)] |
| 94 | + #vis struct #func_name { _never: ::core::convert::Infallible } |
| 95 | + const _: () = { |
| 96 | + fn _assert_args #lifetime_params () #lifetime_where_clause { |
| 97 | + #(let _ = <#first_arg_ty as spacetimedb::rt::ProcedureContextArg>::_ITEM;)* |
| 98 | + #(let _ = <#rest_arg_tys as spacetimedb::rt::ProcedureArg>::_ITEM;)* |
| 99 | + #(let _ = <#ret_ty_for_assert as spacetimedb::rt::IntoProcedureResult>::to_result;)* |
| 100 | + } |
| 101 | + }; |
| 102 | + impl #func_name { |
| 103 | + fn invoke(__ctx: spacetimedb::ProcedureContext, __args: &[u8]) -> spacetimedb::ProcedureResult { |
| 104 | + spacetimedb::rt::invoke_procedure(#func_name, __ctx, __args) |
| 105 | + } |
| 106 | + } |
| 107 | + #[automatically_derived] |
| 108 | + impl spacetimedb::rt::FnInfo for #func_name { |
| 109 | + /// The type of this function. |
| 110 | + type Invoke = spacetimedb::rt::ProcedureFn; |
| 111 | + |
| 112 | + /// The function kind, which will cause scheduled tables to accept procedures. |
| 113 | + type FnKind = spacetimedb::rt::FnKindProcedure<#ret_ty_for_info>; |
| 114 | + |
| 115 | + /// The name of this function |
| 116 | + const NAME: &'static str = #procedure_name; |
| 117 | + |
| 118 | + /// The parameter names of this function |
| 119 | + const ARG_NAMES: &'static [Option<&'static str>] = &[#(#opt_arg_names),*]; |
| 120 | + |
| 121 | + /// The pointer for invoking this function |
| 122 | + const INVOKE: spacetimedb::rt::ProcedureFn = #func_name::invoke; |
| 123 | + |
| 124 | + /// The return type of this function |
| 125 | + fn return_type(ts: &mut impl spacetimedb::sats::typespace::TypespaceBuilder) -> Option<spacetimedb::sats::AlgebraicType> { |
| 126 | + Some(<#ret_ty_for_info as spacetimedb::SpacetimeType>::make_type(ts)) |
| 127 | + } |
| 128 | + } |
| 129 | + }) |
| 130 | +} |
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