Module rdftk_core::resource

Implementation of the Resource pattern as a kind of statement builder. As a builder type the interface is only additive, no update or remove methods exist.

Each Resource comprises a common subject value and a set of predicates each of which may have multiple associated values. It should therefore be noted that calling a predicate method will add a new value, and not replace any existing value. New resource instances can be used directly as the object of a predicate and so nested or related resources can be written inline. This is particulary useful where the object is a blank node.

Additionally a Predicate builder is provided where it is more readable to add only the values individually rather than repeating the same predicate IRI as the Resource interface requires. The interface for Predicate is intended to be a precise sub-set of the Resource methods so that the same look and feel is maintained.

Example

The following short example shows the use of Resource, and a nested resource, to build a small RDF model. Once a resource is created it can be converted into a vector of Statements for either writing out or constructing a Graph instance.

use rdftk_core::{Literal, Resource, Statement};
use rdftk_iri::IRI;
use rdftk_names::{dc::elements as dc, foaf, rdf};
use std::str::FromStr;

fn contact(name: &str) -> IRI {
    IRI::from_str(&format!(
        "http://www.w3.org/2000/10/swap/pim/contact#{}",
        name
    ))
    .unwrap()
}

let resource =
    Resource::named(IRI::from_str("http://en.wikipedia.org/wiki/Tony_Benn").unwrap().into())
        .value_of(dc::publisher().clone(), Literal::new("Wikipedia"))
        .value_of(dc::title().clone(), Literal::new("Tony Benn"))
        .resource(
            dc::description().clone(),
            Resource::blank()
                .resource_named(rdf::a_type().clone(), foaf::person().clone())
                .value_of(foaf::name().clone(), Literal::new("Tony Benn"))
                .to_owned(),
        )
        .to_owned();

let sts: Vec<Statement> = resource.into();
assert_eq!(sts.len(), 5);

for st in sts {
    println!("{}", st);
}

The output from the example above will look like this, although blank node identifiers will likely be different.

<http://en.wikipedia.org/wiki/Tony_Benn> <http://purl.org/dc/elements/1.1/title> "Tony Benn" .
_:B1 <http://xmlns.com/foaf/0.1/name> "Tony Benn" .
_:B1 <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://xmlns.com/foaf/0.1/Person> .
<http://en.wikipedia.org/wiki/Tony_Benn> <http://purl.org/dc/elements/1.1/description> _:B1 .
<http://en.wikipedia.org/wiki/Tony_Benn> <http://purl.org/dc/elements/1.1/publisher> "Wikipedia" .

Structs

Predicate	A predicate builder type, optionally used for multi-valued predicates.
Resource	The main resource builder type.