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31 lines
1.0 KiB
Rust
31 lines
1.0 KiB
Rust
#![cfg_attr(feature = "nightly", feature(allow_internal_unstable))]
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#![cfg_attr(feature = "nightly", allow(internal_features))]
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use proc_macro::TokenStream;
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mod newtype;
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/// Creates a struct type `S` that can be used as an index with
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/// `IndexVec` and so on.
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///
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/// There are two ways of interacting with these indices:
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///
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/// - The `From` impls are the preferred way. So you can do
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/// `S::from(v)` with a `usize` or `u32`. And you can convert back
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/// to an integer with `u32::from(s)`.
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///
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/// - Alternatively, you can use the methods `S::new(v)` and `s.index()`
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/// to create/return a value.
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///
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/// Internally, the index uses a u32, so the index must not exceed
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/// `u32::MAX`. You can also customize things like the `Debug` impl,
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/// what traits are derived, and so forth via the macro.
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#[proc_macro]
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#[cfg_attr(
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feature = "nightly",
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allow_internal_unstable(step_trait, rustc_attrs, trusted_step, spec_option_partial_eq)
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)]
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pub fn newtype_index(input: TokenStream) -> TokenStream {
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newtype::newtype(input)
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}
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