Scattered Collections

The crate is part of the linktime project.

crate		docs	version
linktime	Convenience crate for ctor, dtor and link-section
ctor	Module initialization functions before main
dtor	Module shutdown functions before main
link-section	Linker-managed typed (slices) and untyped sections
scattered-collect	Linker-managed collections: slices, sorted slices, maps

A crate for defining linker-managed scattered collections in Rust.

The collections come in a 'referenced' and 'unreferenced' variant. The referenced variants allow you to access the items as static handles at the declaration site, while the unreferenced variants allow you to access the items as a slice only. The latter, unreferenced variants may be more efficient.

Zero-allocation collections

The collections are all zero-allocation. This means that they can be used in no-std/no-alloc environments, and that they do not contribute to heap usage whatsoever.

Collections

• [ScatteredIterable]: A collection of items that are available only via iterator.
• [ScatteredSlice]: A collection of sized items that collected into a slice in an arbitrary order.
• [ScatteredSortedSlice]: A collection of items that are available via slice, in sorted order.
• [ScatteredReferencedSlice]: A collection of items collected into a slice (link order), with each static item auto-wrapped as [referenced_slice::Ref].
• [ScatteredSortedReferencedSlice]: A collection of sized items that are available both via sorted slice and via reference at the declaration site (auto-wrapped as [sorted_referenced_slice::Ref]).
• [ScatteredMap]: A collection of key-value pairs that are available via slice, as well as indexed by key.

Scatter/Gather syntax

The collections are defined as a single scatter call with multiple gather calls that submit items to the collection.

# use scattered_collect::{gather, scatter, slice::ScatteredSlice};
# struct DatabaseDriver(&'static str);
#[gather]
static COLLECTION: ScatteredSlice<DatabaseDriver>;

... and then elsewhere in your crate:

# mod root { // doctests have weird scope for macros...
# use scattered_collect::{gather, scatter, slice::ScatteredSlice};
# struct DatabaseDriver(&'static str);
# #[gather] static COLLECTION: ScatteredSlice<DatabaseDriver>;

mod postgres {
    # use super::*;
    #[scatter(COLLECTION)]
    static POSTGRES_DRIVER: DatabaseDriver = DatabaseDriver("postgres" /*, ...*/);
}

mod mysql {
    # use super::*;
    # struct DatabaseDriver(&'static str);
    #[scatter(COLLECTION)]
    static MYSQL_DRIVER: DatabaseDriver = DatabaseDriver("mysql" /*, ...*/);
}
# }