rdf-data-factory
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    1.1.0 • Public • Published

    RDF Data Factory

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    This package contains an implementation of the RDF/JS Data model. It works in both JavaScript and TypeScript.

    Concretely, it provides an implementation of the following interfaces:

    • DataFactory: A factory for instantiating RDF terms and quads.
    • NamedNode: A term that contains an IRI.
    • BlankNode: A term that represents an RDF blank node with a label.
    • Literal: A term that represents an RDF literal, containing a string with an optional language tag or datatype.
    • Variable: A term that represents a variable.
    • DefaultGraph: A singleton term instance that represents the default graph.

    If using TypeScript, it is recommended to use this in conjunction with @types/rdf-js.

    Installation

    $ npm install rdf-data-factory

    or

    $ yarn add rdf-data-factory

    This package also works out-of-the-box in browsers via tools such as webpack and browserify.

    Usage

    It is recommended to always create terms via a DataFactory instance:

    import { DataFactory } from 'rdf-data-factory';
    import * as RDF from 'rdf-js';
    
    const factory: RDF.DataFactory = new DataFactory();

    You can pass the following option to define a blank node prefix:

    const factory: RDF.DataFactory = new DataFactory({ blankNodePrefix: 'bnode_' });

    If no blankNodePrefix is passed, it will generate a unique prefix of the form df_[0-9]+_, which ensures there will be no blank nodes clashes when instantiating multiple factories.

    Creating named nodes

    const term: RDF.NamedNode = factory.namedNode('http://example.org');
    console.log(term.value); // 'http://example.org'
    console.log(term.termType); // 'NamedNode'
    console.log(term.equals(term)); // true

    Creating blank nodes

    With a given blank node label:

    const term: RDF.BlankNode = factory.blankNode('bnode');
    console.log(term.value); // 'bnode'
    console.log(term.termType); // 'BlankNode'
    console.log(term.equals(term)); // true

    Autogenerate a blank node label using an internal blank node counter:

    const term: RDF.BlankNode = factory.blankNode();
    console.log(term.value); // 'df-0'
    console.log(term.termType); // 'BlankNode'
    console.log(term.equals(term)); // true

    Reset the blank node label counter:

    factory.resetBlankNodeCounter();

    Creating literals

    Plain string literal:

    const term: RDF.Literal = factory.literal('abc');
    console.log(term.value); // 'abc'
    console.log(term.termType); // 'Literal'
    console.log(term.language); // ''
    console.log(term.datatype); // namedNode('http://www.w3.org/2001/XMLSchema#string')
    console.log(term.equals(term)); // true

    Languaged tagged string literal:

    const term: RDF.Literal = factory.literal('abc', 'en-us');
    console.log(term.value); // 'abc'
    console.log(term.termType); // 'Literal'
    console.log(term.language); // 'en-us'
    console.log(term.datatype); // namedNode('http://www.w3.org/1999/02/22-rdf-syntax-ns#langString')
    console.log(term.equals(term)); // true

    Datatyped literal:

    const term: RDF.Literal = factory.literal('1.2', factory.namedNode('http://www.w3.org/2001/XMLSchema#double'));
    console.log(term.value); // 'abc'
    console.log(term.termType); // 'Literal'
    console.log(term.language); // ''
    console.log(term.datatype); // namedNode('http://www.w3.org/2001/XMLSchema#double')
    console.log(term.equals(term)); // true

    Creating variables

    const term: RDF.Variable = factory.variable('myVar');
    console.log(term.value); // 'myVar'
    console.log(term.termType); // 'Variable'
    console.log(term.equals(term)); // true

    Getting the default graph

    This will always produce the same default graph instance;

    const term: RDF.DefaultGraph = factory.defaultGraph();
    console.log(term.value); // ''
    console.log(term.termType); // 'DefaultGraph'
    console.log(term.equals(term)); // true

    Creating quads

    Create a triple in the default graph:

    const quad: RDF.Quad = factory.quad(
      factory.namedNode('ex:s'),
      factory.namedNode('ex:p'),
      factory.literal('o'),
    );
    console.log(term.subject); // An RDF.Term
    console.log(term.predicate); // An RDF.Term
    console.log(term.object); // An RDF.Term
    console.log(term.graph); // An RDF.Term, in this case defaultGraph()
    console.log(quad.equals(quad)); // true

    Create a triple in a named graph:

    const quad: RDF.Quad = factory.quad(
      factory.namedNode('ex:s'),
      factory.namedNode('ex:p'),
      factory.literal('o'),
      factory.namedNode('ex:g'),
    );
    console.log(term.subject); // An RDF.Term
    console.log(term.predicate); // An RDF.Term
    console.log(term.object); // An RDF.Term
    console.log(term.graph); // An RDF.Term
    console.log(quad.equals(quad)); // true

    Since a Quad is also a Term, it is possible to annotate Quad's by nesting them:

    const quad: RDF.Quad = factory.quad(
      factory.quad(
        factory.namedNode('ex:s'),
        factory.namedNode('ex:p1'),
        factory.literal('o'),
      ),
      factory.namedNode('ex:p2'),
      factory.literal('o'),
    );

    Copying terms

    Create a deep copy of the given term:

    const term1 = factory.namedNode('ex:s');
    const term1 = factory.fromTerm(term1);

    This is useful if you need to transform terms from another data factory.

    Copying quads

    Create a deep copy of the given quad:

    const quad1: RDF.Quad = factory.quad(
      factory.namedNode('ex:s'),
      factory.namedNode('ex:p'),
      factory.literal('o'),
    );
    const quad2 = factory.fromQuad(quad1);

    This is useful if you need to transform quads from another data factory.

    Nested quads will be copied recursively to produce an actual deep copy.

    License

    This software is written by Ruben Taelman.

    This code is released under the MIT license.

    Install

    npm i rdf-data-factory

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    10,089

    Version

    1.1.0

    License

    MIT

    Unpacked Size

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    Total Files

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    Collaborators

    • rubensworks