Crate oxgraph_layout_util 

Shared layout primitives for OxGraph graph and hypergraph crates.

Two responsibilities live here:

• Build-time (BuildIndex, id_to_slot, slot_or_max, index_from_usize, build_offset_index): validate dense IDs against a known count, convert usize slots back into a typed index width, and flatten per-bucket payloads into CSR-style (offsets, items) pairs. Used by oxgraph-graph-build and oxgraph-hyper-build.
• Read-time (ZerocopyWord, OffsetIntegrityIssue, check_offsets_monotonic, check_value_range, check_offset_section): walk borrowed offset arrays at view-open time to enforce length matches count + 1, first offset is zero, offsets non-decreasing, the final offset matches the value-array length, and every value fits in the dense bound. Used by oxgraph-csr and oxgraph-hyper-bcsr.

Helpers return small typed data enums (IdOutOfBounds, OffsetOverflow, OffsetIntegrityIssue) instead of crate-specific error types. Callers map the issue to their own typed error at the boundary.

no_std + alloc (build-time primitives need Vec). No public domain semantics. No dependency on any other oxgraph crate.

Enums

IdOutOfBounds

Reasons an ID failed dense bounds validation.

OffsetIntegrityIssue

Reasons a borrowed offset or value array failed structural validation.

OffsetOverflow

Reasons a usize could not be represented in a target index width during builder offset construction.

Traits

BuildIndex

Unsigned dense ID width usable by graph and hypergraph builders.

ZerocopyWord

Borrowed offset or value word usable by offset-integrity primitives.

Functions

build_offset_index

Flattens per-bucket payloads into a (offsets, items) pair.

check_offset_section

Validates one offset section against expected_count rows and a backing values array of length value_len.

check_offsets_monotonic

Verifies offsets[0] == 0 and that offsets is non-decreasing.

check_value_range

Verifies every value in values is less than bound.

id_to_slot

Validates that id’s usize representation is less than count.

index_from_usize

Converts a usize value into the target index width.

slot_or_max

Returns id’s usize representation, or usize::MAX when it does not fit in usize on the current target.