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https://issues.apache.org/jira/browse/JENA-1391?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16155844#comment-16155844
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A. Soroka commented on JENA-1391:
---------------------------------
I can see the relevance of the lambda question with respect to {{add}} and
{{remove}} but not WRT the others.
If that is a particular motivation for this ticket, perhaps it might worthwhile
to keep the {{Dataset}} simple, introduce a {{DatasetLib}} (as [~andy.seaborne]
suggests) for everything but {{add}} and {{remove}} and introduce some
{{java.util.stream.Collector}} s for adding and removing from a {{Dataset}}.
Something along the lines of:
{code}
class Collectors {
public Collector<Dataset, ?, Dataset> adder(Dataset d) { .... }
public Collector<Dataset, ?, Dataset> remover(Dataset d) { .... }
public Collector<Model, ?, Model> adder(Model m) { .... }
public Collector<Model, ?, Model> remover(Model m) { .... }
}
{code}
which would collect things up from {{Stream}} s as needed. That could find a
more general audience. In fact, I wouldn't mind dealing with JENA-1390 in a
similar way, by putting a simple {{collect}} method in someplace like the
{{Iter}} library in {{jena-base}} and then having factories of common
"collectors" available in the modules where they would make sense. If that
sounds attractive, I can work up a PR.
> Add Convenience Methods to Dataset
> ----------------------------------
>
> Key: JENA-1391
> URL: https://issues.apache.org/jira/browse/JENA-1391
> Project: Apache Jena
> Issue Type: Improvement
> Components: ARQ
> Affects Versions: Jena 3.4.0
> Reporter: Adam Jacobs
> Priority: Trivial
>
> The Dataset interface could provide several convenience methods similar to
> the Model interface, allowing usability of RDF quads on par with RDF triples.
> Specific examples include,
> # add(Dataset)
> # remove(Dataset)
> # union(Dataset)
> # intersection(Dataset)
> # difference(Dataset)
> # isEmpty()
> Following is a possible implementation of these methods.
> {code:java}
> default Dataset add(Dataset d) {
> this.getDefaultModel().add(d.getDefaultModel());
> d.listNames().forEachRemaining(name ->
> this.getNamedModel(name).add(d.getNamedModel(name)));
> return this;
> }
> default Dataset remove(Dataset d) {
> this.getDefaultModel().remove(d.getDefaultModel());
> d.listNames().forEachRemaining(name ->
> this.getNamedModel(name).remove(d.getNamedModel(name)));
> return this;
> }
> default Dataset union(Dataset d) {
> return DatasetFactory.create().add(this).add(d);
> }
> default Dataset difference(Dataset d) {
> Dataset output = DatasetFactory.create();
>
> output.setDefaultModel(this.getDefaultModel().difference(d.getDefaultModel()));
> this.listNames().forEachRemaining(name -> {
> Model difference =
> this.getNamedModel(name).difference(d.getNamedModel(name));
> if (!difference.isEmpty()) output.addNamedModel(name, difference);
> });
> return output;
> }
> default Dataset intersection(Dataset d) {
> Dataset output = DatasetFactory.create();
>
> output.setDefaultModel(this.getDefaultModel().intersection(d.getDefaultModel()));
> Set<String> names = this.names();
> names.retainAll(d.names());
> names.forEach(name -> {
> Model intersection =
> this.getNamedModel(name).intersection(d.getNamedModel(name));
> if (!intersection.isEmpty()) output.addNamedModel(name,
> intersection);
> });
> return output;
> }
> default Set<String> names() {
> Set<String> names = new HashSet<>();
> this.listNames().forEachRemaining(names::add);
> return names;
> }
> default boolean isEmpty() {
> return this.asDatasetGraph().isEmpty();
> }
> {code}
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