| // tidy-alphabetical-start |
| #![cfg_attr(feature = "nightly", allow(internal_features))] |
| #![cfg_attr(feature = "nightly", feature(allow_internal_unstable))] |
| // tidy-alphabetical-end |
| |
| use proc_macro::TokenStream; |
| |
| mod newtype; |
| |
| /// Creates a struct type `S` that can be used as an index with |
| /// `IndexVec` and so on. |
| /// |
| /// There are two ways of interacting with these indices: |
| /// |
| /// - The `From` impls are the preferred way. So you can do |
| /// `S::from(v)` with a `usize` or `u32`. And you can convert back |
| /// to an integer with `u32::from(s)`. |
| /// |
| /// - Alternatively, you can use the methods `S::new(v)` and `s.index()` |
| /// to create/return a value. |
| /// |
| /// Internally, the index uses a u32, so the index must not exceed |
| /// `u32::MAX`. |
| /// |
| /// The impls provided by default are Clone, Copy, PartialEq, Eq, and Hash. |
| /// |
| /// Accepted attributes for customization: |
| /// - `#[derive(HashStable_Generic)]`/`#[derive(HashStable)]`: derives |
| /// `HashStable`, as normal. |
| /// - `#[encodable]`: derives `Encodable`/`Decodable`. |
| /// - `#[orderable]`: derives `PartialOrd`/`Ord`, plus step-related methods. |
| /// - `#[debug_format = "Foo({})"]`: derives `Debug` with particular output. |
| /// - `#[max = 0xFFFF_FFFD]`: specifies the max value, which allows niche |
| /// optimizations. The default max value is 0xFFFF_FF00. |
| /// - `#[gate_rustc_only]`: makes parts of the generated code nightly-only. |
| #[proc_macro] |
| #[cfg_attr(feature = "nightly", allow_internal_unstable(step_trait, rustc_attrs, trusted_step))] |
| pub fn newtype_index(input: TokenStream) -> TokenStream { |
| newtype::newtype(input) |
| } |
