Crate grdf

Expand description

The Resource Description Framework (RDF) is a powerful method for modeling data and knowledge defined by the World Wide Web Consortium (W3C). A RDF dataset consists in a collection of graphs connecting nodes, values and predicates. This crate provides traits and implementations of Generalized RDF (gRDF) where nodes, values and predicates have the same representation.

Note that this crates requires the nightly compiler. It needs Generic Associated Typed (GAT) to work properly, which are still being implemented.

Basic usage

Exploring a dataset

Each Dataset implementation provides many iterators to explore the data. One simple way is to iterate through the quad of the dataset:

for Quad(subject, predicate, object, graph) in dataset.quads() {
  // do something
}

Another way is to access each graph individually using Dataset::graph. For a given graph, it is then possible to iterate through the triples of the graph:

let graph = dataset.graph(id).unwrap();

for Triple(subject, predicate, object) in graph.triples() {
  // do something
}

It is also possible to explore the graph logically, subject by subject, predicate by predicate, object by object:

// for each subject of the graph...
for (subject, predicates) in graph.subjects() {
  // for each predicate it is subject...
  for (predicate, objects) in predicates {
    // for each triple (subject, predicate, object)...
    for object in objects {
      // do something
    }
  }
}

Inserting new data

Insertion can be done on MutableDataset implementations using MutableDataset::insert:

let mut dataset: HashDataset<Term> = HashDataset::new();
dataset.insert(Quad(subject, predicate, object, graph));

Again it is possible to access each graph of the dataset mutably:

let mut graph = dataset.graph_mut(id).unwrap();
graph.insert(Triple(subject, predicate, object));

Custom node type

The type used to represent RDF nodes (subjects, predicate and objects) is a parameter of the dataset. Anything can be used although this crate provide a default Term type that represents generic RDF nodes (blank nodes, IRI-named nodes and literal values).