1 files changed, 93 insertions, 0 deletions
diff --git a/vendor/github.com/golang/geo/s2/query_entry.go b/vendor/github.com/golang/geo/s2/query_entry.go
new file mode 100644
index 000000000..65e819e3a
--- /dev/null
+++ b/vendor/github.com/golang/geo/s2/query_entry.go
@@ -0,0 +1,93 @@
+// Copyright 2020 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package s2
+
+import "container/heap"
+
+// A queryQueueEntry stores CellIDs and distance from a target. It is used by the
+// different S2 Query types to efficiently build their internal priority queue
+// in the optimized algorithm implementations.
+type queryQueueEntry struct {
+	// A lower bound on the distance from the target to ID. This is the key
+	// of the priority queue.
+	distance distance
+
+	// The cell being queued.
+	id CellID
+
+	// If the CellID belongs to a ShapeIndex, this field stores the
+	// corresponding ShapeIndexCell. Otherwise ID is a proper ancestor of
+	// one or more ShapeIndexCells and this field stores is nil.
+	indexCell *ShapeIndexCell
+}
+
+// queryQueue is used by the optimized algorithm to maintain a priority queue of
+// unprocessed CellIDs, sorted in increasing order of distance from the target.
+type queryQueue struct {
+	queue queryPQ
+}
+
+// newQueryQueue returns a new initialized queryQueue.
+func newQueryQueue() *queryQueue {
+	q := &queryQueue{
+		queue: make(queryPQ, 0),
+	}
+	heap.Init(&q.queue)
+	return q
+}
+
+// push adds the given entry to the top of this queue.
+func (q *queryQueue) push(e *queryQueueEntry) {
+	heap.Push(&q.queue, e)
+}
+
+// pop returns the top element of this queue.
+func (q *queryQueue) pop() *queryQueueEntry {
+	return heap.Pop(&q.queue).(*queryQueueEntry)
+}
+
+func (q *queryQueue) size() int {
+	return q.queue.Len()
+}
+
+func (q *queryQueue) reset() {
+	q.queue = q.queue[:0]
+}
+
+// queryPQ is a priority queue that implements the heap interface.
+type queryPQ []*queryQueueEntry
+
+func (q queryPQ) Len() int { return len(q) }
+func (q queryPQ) Less(i, j int) bool {
+	return q[i].distance.less(q[j].distance)
+}
+
+// Swap swaps the two entries.
+func (q queryPQ) Swap(i, j int) {
+	q[i], q[j] = q[j], q[i]
+}
+
+// Push adds the given entry to the queue.
+func (q *queryPQ) Push(x interface{}) {
+	item := x.(*queryQueueEntry)
+	*q = append(*q, item)
+}
+
+// Pop returns the top element of the queue.
+func (q *queryPQ) Pop() interface{} {
+	item := (*q)[len(*q)-1]
+	*q = (*q)[:len(*q)-1]
+	return item
+}