Add cursor support

src/Jenssegers/Mongodb/Query/Builder.php

@@ -8,6 +8,7 @@ use Illuminate\Database\Query\Builder as BaseBuilder;
 use Illuminate\Database\Query\Expression;
 use Illuminate\Support\Arr;
 use Illuminate\Support\Collection;
+use Illuminate\Support\LazyCollection;
 use Illuminate\Support\Str;
 use Jenssegers\Mongodb\Connection;
 use MongoCollection;
@@ -15,7 +16,12 @@ use MongoDB\BSON\Binary;
 use MongoDB\BSON\ObjectID;
 use MongoDB\BSON\Regex;
 use MongoDB\BSON\UTCDateTime;
+use RuntimeException;
 
+/**
+ * Class Builder
+ * @package Jenssegers\Mongodb\Query
+ */
 class Builder extends BaseBuilder
 {
     /**
@@ -209,12 +215,25 @@ class Builder extends BaseBuilder
         return $this->getFresh($columns);
     }
 
+    /**
+     * @inheritdoc
+     */
+    public function cursor($columns = [])
+    {
+        $result =  $this->getFresh($columns, true);
+        if ($result instanceof LazyCollection) {
+            return $result;
+        }
+        throw new RuntimeException("Query not compatible with cursor");
+    }
+
     /**
      * Execute the query as a fresh "select" statement.
      * @param array $columns
-     * @return array|static[]|Collection
+     * @param bool $returnLazy
+     * @return array|static[]|Collection|LazyCollection
      */
-    public function getFresh($columns = [])
+    public function getFresh($columns = [], $returnLazy = false)
     {
         // If no columns have been specified for the select statement, we will set them
         // here to either the passed columns, or the standard default of retrieving
@@ -402,6 +421,14 @@ class Builder extends BaseBuilder
             // Execute query and get MongoCursor
             $cursor = $this->collection->find($wheres, $options);
 
+            if ($returnLazy) {
+                return LazyCollection::make(function () use ($cursor) {
+                    foreach ($cursor as $item) {
+                        yield $item;
+                    }
+                });
+            }
+
             // Return results as an array with numeric keys
             $results = iterator_to_array($cursor, false);
             return $this->useCollections ? new Collection($results) : $results;