diff options
Diffstat (limited to 'mingling_macros/src/lib.rs')
| -rw-r--r-- | mingling_macros/src/lib.rs | 62 |
1 files changed, 61 insertions, 1 deletions
diff --git a/mingling_macros/src/lib.rs b/mingling_macros/src/lib.rs index c955e36..ce3455e 100644 --- a/mingling_macros/src/lib.rs +++ b/mingling_macros/src/lib.rs @@ -165,7 +165,7 @@ use attr::completion; use attr::dispatcher_clap; #[cfg(feature = "extras")] use attr::program_setup; -use attr::{chain, help, renderer}; +use attr::{chain, help, metadata, renderer}; use derive::{enum_tag, grouped}; #[cfg(feature = "extras")] use func::entry; @@ -209,6 +209,7 @@ pub(crate) static RENDERERS: Registry = OnceLock::new(); pub(crate) static CHAINS_EXIST: Registry = OnceLock::new(); pub(crate) static RENDERERS_EXIST: Registry = OnceLock::new(); pub(crate) static HELP_REQUESTS: Registry = OnceLock::new(); +pub(crate) static METADATA: Registry = OnceLock::new(); /// Checks if a variant name already exists in a registered set. /// Returns a `compile_error` token stream if a duplicate is found. @@ -1297,6 +1298,26 @@ pub fn register_help(input: TokenStream) -> TokenStream { func::register_help::register_help(input) } +/// Registers metadata mapping between an enum variant and a metadata type. +/// +/// This macro is used internally by the `#[metadata]` attribute and is also +/// available for manual registration if needed. +/// +/// # Syntax +/// +/// ```rust,ignore +/// register_metadata!(EntryVariant, MetadataType); +/// ``` +/// +/// This adds an entry to the global `METADATA` registry, mapping the enum +/// variant for `EntryVariant` to the metadata provider trait +/// `::mingling::Metadata<MetadataType>`. The entry is consumed by +/// `gen_program!` to generate the `get_metadata` method of `ProgramCollect`. +#[proc_macro] +pub fn register_metadata(input: TokenStream) -> TokenStream { + func::register_metadata::register_metadata_impl(input) +} + /// Registers a dispatcher at compile time for the `dispatch_tree` feature. /// /// This macro is called internally by `dispatcher!` when the `dispatch_tree` @@ -1404,6 +1425,45 @@ pub fn help(attr: TokenStream, item: TokenStream) -> TokenStream { help::help_attr(item) } +/// Declares compile-time metadata for an entry variant. +/// +/// The `#[metadata]` attribute attaches an arbitrary, compile-time-typed value +/// to an entry. The annotated function becomes the provider for the metadata: +/// its return type is the metadata type, and the attribute argument names the +/// entry enum variant the metadata belongs to. +/// +/// The macro works by: +/// 1. Generating `impl ::mingling::Metadata<ReturnType> for EntryVariant` whose +/// `init_metadata()` calls the annotated function. +/// 2. Registering the entry via `register_metadata!` in the global `METADATA` +/// registry so that `gen_program!` emits the `get_metadata` method. +/// 3. Keeping the original function unchanged for direct calls. +/// +/// # Syntax +/// +/// ```rust,ignore +/// #[metadata(EntryGreet)] +/// fn greet_desc() -> Description { +/// Description { desc: "ok".into() } +/// } +/// ``` +/// +/// The metadata is later retrieved with `ProgramCollect::get_metadata`: +/// +/// ```rust,ignore +/// let desc = ThisProgram::get_metadata::<Description>(ThisProgram::EntryGreet); +/// ``` +/// +/// # Requirements +/// +/// - The attribute argument must be the enum variant to attach metadata to. +/// - The function must take no parameters and return a concrete type. +/// - The function cannot be async. +#[proc_macro_attribute] +pub fn metadata(attr: TokenStream, item: TokenStream) -> TokenStream { + metadata::metadata_attr(attr, item) +} + /// Marker attribute for the Mingling lint system. /// /// The content of this attribute is ignored by rustc and reserved for |