fa-sharp
1d6708e23b
- Added public `Error`, `Result`, `InitFuture`, and `ShutdownFuture` aliases. - Added `TypeMapState` as the default state instead of `Arc<TypeMap>`. - Added `App::route`, `App::mount`, and `App::store`. - Changed `App::init()` to return `InitializedApp<S>`. - Added `InitializedApp::router()`, `state()`, `into_parts()`, and `shutdown()`. - Made shutdown hooks fallible: `Result<()>`. - Made `AdHocPlugin::on_shutdown` accept capturing closures. - Added `Default` for `App` and `AdHocPlugin`. Improved AppState macro: - Uses `axum_app_wrapper::Error`. - Supports generic state structs. - Fixed the stale `Arc<AppState>` doc snippet.
75 lines
2.5 KiB
Rust
75 lines
2.5 KiB
Rust
use proc_macro::TokenStream;
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use quote::quote;
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use syn::{Data, DeriveInput, Fields, parse_macro_input};
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/// Derive macro that implements [`TryFrom<TypeMap>`] for `T`.
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///
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/// Apply this to your state struct and each named field will be extracted from the
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/// [`TypeMap`] by type automatically. Keep in mind each field must be of a
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/// different type — if you need to store multiple values of the same type, use
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/// a wrapper like `struct Foo(type)` or `enum Foo { A(type), B(type) }`.
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///
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/// How the state is stored and cloned is up to you —
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/// if you want cheap clones, wrap your fields in `Arc` individually or use
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/// `Arc<AppState>` as your axum state type.
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///
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/// ```ignore
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/// #[derive(AppState)]
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/// struct AppState {
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/// config: Config,
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/// pool: Pool,
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/// db: Db,
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/// }
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/// // To wrap the whole state in `Arc`, implement `TryFrom<TypeMap>` for `Arc<AppState>`:
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/// impl TryFrom<TypeMap> for Arc<AppState> {
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/// type Error = axum_app_wrapper::Error;
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///
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/// fn try_from(map: TypeMap) -> Result<Self, Self::Error> {
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/// Ok(Arc::new(AppState::try_from(map)?))
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/// }
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/// }
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/// ```
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#[proc_macro_derive(AppState)]
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pub fn derive_app_state(input: TokenStream) -> TokenStream {
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let input = parse_macro_input!(input as DeriveInput);
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let name = &input.ident;
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let fields = match &input.data {
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Data::Struct(s) => match &s.fields {
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Fields::Named(f) => &f.named,
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_ => {
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return syn::Error::new_spanned(
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name,
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"#[derive(AppState)] only supports structs with named fields",
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)
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.to_compile_error()
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.into();
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}
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},
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_ => {
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return syn::Error::new_spanned(
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name,
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"#[derive(AppState)] can only be applied to structs",
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)
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.to_compile_error()
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.into();
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}
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};
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let field_names = fields.iter().map(|f| &f.ident);
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let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl();
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quote! {
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impl #impl_generics ::std::convert::TryFrom<::axum_app_wrapper::TypeMap> for #name #ty_generics #where_clause {
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type Error = ::axum_app_wrapper::Error;
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fn try_from(mut map: ::axum_app_wrapper::TypeMap) -> ::std::result::Result<Self, Self::Error> {
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Ok(#name {
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#(#field_names: ::axum_app_wrapper::extract_type_field(&mut map)?,)*
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})
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}
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}
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}
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.into()
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}
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