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https://issues.apache.org/jira/browse/GROOVY-10223?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17558504#comment-17558504
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Eric Milles commented on GROOVY-10223:
--------------------------------------
Here is my "iterator()" implementation, in case someone wants to try this out
as a category method or whatever. I do not see enough value to pursue it plus
{{OptionalInt}}, {{OptionalLong}} and {{OptionalDouble}} variants.
{code:java}
/**
* If a value is present in the {@code Optional}, returns a single-element
* {@code Iterator}; otherwise returns an empty {@code Iterator}.
*
* <pre class="groovyTestCase">
* def iter = Optional.empty().iterator()
* assert !iter.hasNext()
*
* iter = Optional.of('x').iterator()
* assert iter.hasNext()
* assert iter.next() == 'x'
* assert !iter.hasNext()
*
* // for-each supported via iterator()
* int values = 0
* for (value in Optional.empty()) {
* values += 1
* }
* assert values == 0
* for (value in Optional.of('x')) {
* assert value == 'x'
* values += 1
* }
* assert values == 1
* </pre>
*/
public static <T> Iterator<T> iterator(final Optional<T> self) {
return
self.map(Collections::singleton).orElseGet(Collections::emptySet).iterator();
}
{code}
> Add support for Optional to DefaultTypeTransformation.asCollection()
> --------------------------------------------------------------------
>
> Key: GROOVY-10223
> URL: https://issues.apache.org/jira/browse/GROOVY-10223
> Project: Groovy
> Issue Type: New Feature
> Components: groovy-jdk
> Reporter: Stephen Smith
> Assignee: Eric Milles
> Priority: Trivial
> Labels: features
>
> The JDK recently added support for *Optional::stream()* which returns a
> stream containing either the unwrapped value or an empty stream if the
> *Optional* is empty.
> In the groovy-jdk, using iteration however will call
> {noformat}
> DefaultTypeTransformation.asCollection(){noformat}
> which does not specifically check for type *Optional*, instead it will just
> wrap the *Optional* itself in a *List* rather than the unwrapped value as the
> default behavior.
> Adding an _if else_ clause will allow using the Optional as either a single
> or empty list.
> {code:java}
> if (value instanceOf Optional) {
> return ((Optional)value).map(List::of).orElse(List.of())
> }{code}
> Alternatively, add an *asList()* to the Optional class.
> (edit: 2021-09-13, missing bracket in code example)
>
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