scattered-collect 0.3.0

Link-time collections for Rust (distributed slices, registries)
Documentation 
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//! A collection of sized items gathered into a slice in arbitrary link order.
#![doc = concat!("```rust\n", include_str!("../examples/slice.rs"), "\n```\n")]

use link_section::TypedSection;

/// A collection of sized items gathered into a slice in arbitrary link order.
///
/// For a sorted slice without per-item handles, use [`crate::ScatteredSortedSlice`]. For
/// arbitrary link order with `static` handles at each scatter site, use
/// [`crate::ScatteredReferencedSlice`]. For sorted data with stable per-item references,
/// use [`crate::ScatteredSortedReferencedSlice`]. For key lookup, use [`crate::ScatteredMap`].
#[doc = concat!("```rust\n", include_str!("../examples/slice.rs"), "\n```\n")]
pub struct ScatteredSlice<T: 'static> {
    section: &'static TypedSection<T>,
}

impl<T> ScatteredSlice<T> {
    #[doc(hidden)]
    #[allow(unsafe_code)]
    pub const unsafe fn new(section: &'static TypedSection<T>) -> Self {
        Self { section }
    }
}

impl<T> ::core::ops::Deref for ScatteredSlice<T> {
    type Target = [T];
    fn deref(&self) -> &Self::Target {
        self.section
    }
}

/// Declare a scattered slice.
#[macro_export]
#[doc(hidden)]
macro_rules! __slice {
    (@gather $(#[$meta:meta])* $vis:vis static $name:ident: $collection:ident < $ty:ty >;) => {
        #[doc(hidden)]
        #[allow(unused)]
        $vis use $crate::__slice as $name;

        $(#[$meta])*
        $vis static $name: $collection<$ty> = {
            $crate::__support::link_section::declarative::section!(
                #[section(typed)]
                static $name: $crate::__support::link_section::TypedSection<$ty>;
            );

            unsafe { $crate::slice::ScatteredSlice::new(
                $name.const_deref()
            ) }
        };
    };

    (@scatter [$($meta:tt)*] $(#[$imeta:meta])* $vis:vis $type:ident $name:tt: $ty:ty = $expr:expr;) => {
        $crate::__support::link_section::declarative::in_section!(
            #[in_section(unsafe, name = $($meta)*, type = typed)]
            $(#[$imeta])*
            $vis $type $name: $ty = $expr;
        );
    };
    (($collection:ident => $(#[$imeta:meta])* $vis:vis $type:ident $name:tt: $ty:ty = $expr:expr;)) => {
        $crate::__slice!(
            @scatter [$collection]
            $(#[$imeta])*
            $vis $type $name: $ty = $expr;
        );
    };
}

#[cfg(all(test, not(miri)))]
mod tests {
    pub use super::ScatteredSlice;

    __slice!(@gather pub static TEST_SLICE: ScatteredSlice<u32>;);
    __slice!(@scatter [TEST_SLICE] const _: u32 = 1;);
    __slice!(@scatter [TEST_SLICE] const _: u32 = 3;);
    __slice!(@scatter [TEST_SLICE] const _: u32 = 2;);

    #[test]
    fn test_scattered_slice() {
        assert_eq!(TEST_SLICE.len(), 3);
        assert!(TEST_SLICE.contains(&1));
        assert!(TEST_SLICE.contains(&2));
        assert!(TEST_SLICE.contains(&3));
    }
}