feral-ordering-core

Shared input/output types for FERAL's fill-reducing ordering crates.

This crate defines the locked contract surface that every sibling ordering crate in FERAL (feral-amd, feral-metis, feral-scotch, feral-kahip) implements:

• CscPattern<'_> — borrowed, full-symmetric, 0-based, i32-indexed sparsity pattern.
• OrderingStats — producer-agnostic diagnostic counters (time, optional fill / flop estimates).
• OrderingError — shared error shape with a static Internal(&str) escape hatch.
• CONTRACT_VERSION: u32 — bumped on breaking changes.

Zero dependencies beyond std. The full design rationale lives in dev/plans/ordering-crate-contract.md.

Per-crate contract function

Each ordering crate exposes exactly one contract-conforming function:

pub fn xxx_order(
    pattern: &feral_ordering_core::CscPattern<'_>,
    opts: &XxxOptions,
) -> Result<
    (Vec<i32>, feral_ordering_core::OrderingStats, XxxStats),
    feral_ordering_core::OrderingError,
>;

perm[k] = j means new index k corresponds to old index j (new-to-old). Convenience overloads (e.g. defaults, skipping stats) are allowed but the three-tuple signature above is mandatory.

License

MIT.