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https://issues.apache.org/jira/browse/JENA-1391?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16310292#comment-16310292
]
ASF GitHub Bot commented on JENA-1391:
--------------------------------------
Github user afs commented on a diff in the pull request:
https://github.com/apache/jena/pull/337#discussion_r159528932
--- Diff: jena-base/src/main/java/org/apache/jena/atlas/lib/Pair.java ---
@@ -37,6 +40,30 @@
public A car() { return a ; }
public B cdr() { return b ; }
+ public static class OfSameType<T> extends Pair<T, T> {
+
--- End diff --
Point 3 was the observation
```
public <S, X> S apply(BiFunction<X, X, S> f, Function<T, X> op) {
return f.apply(op.apply(a), op.apply(b));
}
```
could be a function that can acts on `Pair<X,X>`.
```
static public <S, X> S apply(Pair<X,X> pair, BiFunction<X, X, S> f,
Function<T, X> op) {
return f.apply(op.apply(pair.car()), op.apply(pair.cdr()));
}
```
now whether `<S, X>` can meaningfully/usefully be `<S, X extends FOO>` and
interface FOO defines the "to boolean" method,
I don't usually push generics very hard - I leave that to Scala.
> 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
> Assignee: A. Soroka
> 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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