uschindler commented on code in PR #15823:
URL: https://github.com/apache/lucene/pull/15823#discussion_r3010575641
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lucene/core/src/java/org/apache/lucene/util/PriorityQueue.java:
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@@ -174,6 +177,38 @@ public void addAll(Collection<T> elements) {
}
}
+ /**
+ * Adds all elements of the stream into the queue. This method should be
preferred over calling
+ * {@link #add(Object)} in loop if all elements are known in advance as it
builds queue faster.
+ *
+ * <p>If one needs to map or filter element in the iteration of elements in
this method, call this
+ * method with elements wrapped by {@link Stream#map(Function)} or {@link
+ * Stream#filter(Predicate)}, etc. In these cases, this method should be
preferred over calling
+ * {@link #addAll(Collection)}.
+ *
+ * <p>If one tries to add more objects than the maxSize passed in the
constructor, an {@link
+ * ArrayIndexOutOfBoundsException} is thrown. Which may result in parts of
elements added into the
+ * queue, but the heap is still stay in correct state. In this case, if
caller wants to readd or
+ * {@link #updateTop(Object)} with remaining elements, it should use a new
stream, and use {@link
+ * Stream#skip(long)} to skip consumed elements with the delta size of queue.
+ */
+ public void addAll(Stream<T> elements) {
+ // Heap with size S always takes first S elements of the array,
+ // and thus it's safe to fill array further - no actual non-sentinel value
will be overwritten.
+ try {
+ elements.forEachOrdered(
+ element -> {
+ this.heap[size + 1] = element;
+ this.size++;
Review Comment:
Final note: streams are "declarative", that's the key takeaway.
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