oxgraph-csr

Borrowed CSR graph views implementing oxgraph-graph traits.

The first concrete graph layout of the oxgraph crate family. no_std, unsafe-free.

What it is

A CsrGraph borrows validated compressed-sparse-row offset and target slices, native or straight out of a snapshot section, and implements the storage-agnostic graph traits from oxgraph-graph. Validation happens once at construction; traversal after that is slice indexing with no parse step and no copy of the edges.

CSR is optimized for outgoing traversal. Incoming traversal requires a reverse index and is deliberately not implemented here; that is oxgraph-csc, a separate crate so forward and inbound views cannot be mixed at the type level.

Where it sits

oxgraph-graph                     node/edge capability traits
└── oxgraph-csr                 ← this crate (borrowed CSR layout)
    ├── reads oxgraph-snapshot sections (CSR_OFFSETS / CSR_TARGETS)
    ├── reuses oxgraph-layout-util widths and integrity checks
    └── traversed by oxgraph-algo (BFS, PageRank)

Snapshot section kinds are width-coded: each persisted kind is BASE | WIDTH_CODE, where the low two bits select the little-endian word width (u16/u32/u64).

Example

Adapted from the runnable example examples/csr_directed.rs (cargo run -p oxgraph-csr --example csr_directed):

use oxgraph_csr::{CsrGraph, CsrNodeId};
use oxgraph_graph::{EdgeTargetGraph, GraphCounts, OutgoingEdgeCount, OutgoingGraph};

static OFFSETS: &[u32] = &[0, 2, 3, 4, 4];
static TARGETS: &[u32] = &[1, 2, 2, 3];

let graph = CsrGraph::validate(4, OFFSETS, TARGETS)?;

println!("nodes={} edges={}", graph.node_count(), graph.edge_count());
println!("out_degree(0)={}", graph.out_degree(CsrNodeId::new(0)));

for edge in graph.outgoing_edges(CsrNodeId::new(0)) {
    println!("edge={edge:?} target={:?}", graph.target(edge));
}

Opening a view from a packed snapshot instead of native slices is examples/open_snapshot.rs.

Features

Documentation

See docs.rs/oxgraph-csr for the full API and the oxgraph family README for how the layers fit together. Also available through the umbrella crate: cargo add oxgraph --features csr (or graph-build for the builders).

License

MIT. See LICENSE.