[8.x] chunkWhile(): preserve keys, defer to lazy collections

src/Illuminate/Collections/Collection.php

@@ -1078,23 +1078,9 @@ public function chunk($size)
      */
     public function chunkWhile(callable $callback)
     {
-        $chunks = [];
-
-        $chunk = [];
-
-        foreach ($this->items as $current) {
-            if (isset($previous) && ! $callback($previous, $current)) {
-                $chunks[] = new static($chunk);
-                $chunk = [];
-            }
-
-            $chunk[] = $current;
-            $previous = $current;
-        }
-
-        $chunks[] = new static($chunk);
-
-        return new static($chunks);
+        return new static(
+            $this->lazy()->chunkWhile($callback)->mapInto(static::class)
+        );
     }
 
     /**

src/Illuminate/Collections/LazyCollection.php

@@ -1093,22 +1093,29 @@ public function chunkWhile(callable $callback)
         return new static(function () use ($callback) {
             $iterator = $this->getIterator();
 
-            $chunk = [];
+            $chunk = new Collection();
+
+            if ($iterator->valid()) {
+                $chunk[$iterator->key()] = $iterator->current();
+
+                $iterator->next();
+            }
 
             while ($iterator->valid()) {
-                if (isset($previous) && ! $callback($previous, $iterator->current())) {
+                if (! $callback($iterator->current(), $iterator->key(), $chunk)) {
                     yield new static($chunk);
 
-                    $chunk = [];
+                    $chunk = new Collection();
                 }
 
-                $chunk[] = $iterator->current();
-                $previous = $iterator->current();
+                $chunk[$iterator->key()] = $iterator->current();
 
                 $iterator->next();
             }
 
-            yield new static($chunk);
+            if ($chunk->isNotEmpty()) {
+                yield new static($chunk);
+            }
         });
     }
 

tests/Support/SupportCollectionTest.php

@@ -1650,15 +1650,15 @@ public function testChunkWhenGivenLessThanZero($collection)
     public function testChunkWhileOnEqualElements($collection)
     {
         $data = (new $collection(['A', 'A', 'B', 'B', 'C', 'C', 'C']))
-            ->chunkWhile(function ($previous, $current) {
-                return $previous === $current;
+            ->chunkWhile(function ($current, $key, $chunk) {
+                return $chunk->last() === $current;
             });
 
         $this->assertInstanceOf($collection, $data);
         $this->assertInstanceOf($collection, $data->first());
-        $this->assertEquals(['A', 'A'], $data->first()->toArray());
-        $this->assertEquals(['B', 'B'], $data->get(1)->toArray());
-        $this->assertEquals(['C', 'C', 'C'], $data->last()->toArray());
+        $this->assertEquals([0 => 'A', 1 => 'A'], $data->first()->toArray());
+        $this->assertEquals([2 => 'B', 3 => 'B'], $data->get(1)->toArray());
+        $this->assertEquals([4 => 'C', 5 => 'C', 6 => 'C'], $data->last()->toArray());
     }
 
     /**
@@ -1667,17 +1667,17 @@ public function testChunkWhileOnEqualElements($collection)
     public function testChunkWhileOnContiguouslyIncreasingIntegers($collection)
     {
         $data = (new $collection([1, 4, 9, 10, 11, 12, 15, 16, 19, 20, 21]))
-            ->chunkWhile(function ($previous, $current) {
-                return $previous + 1 == $current;
+            ->chunkWhile(function ($current, $key, $chunk) {
+                return $chunk->last() + 1 == $current;
             });
 
         $this->assertInstanceOf($collection, $data);
         $this->assertInstanceOf($collection, $data->first());
-        $this->assertEquals([1], $data->first()->toArray());
-        $this->assertEquals([4], $data->get(1)->toArray());
-        $this->assertEquals([9, 10, 11, 12], $data->get(2)->toArray());
-        $this->assertEquals([15, 16], $data->get(3)->toArray());
-        $this->assertEquals([19, 20, 21], $data->last()->toArray());
+        $this->assertEquals([0 => 1], $data->first()->toArray());
+        $this->assertEquals([1 => 4], $data->get(1)->toArray());
+        $this->assertEquals([2 => 9, 3 => 10, 4 => 11, 5 => 12], $data->get(2)->toArray());
+        $this->assertEquals([6 => 15, 7 => 16], $data->get(3)->toArray());
+        $this->assertEquals([8 => 19, 9 => 20, 10 => 21], $data->last()->toArray());
     }
 
     /**

tests/Support/SupportLazyCollectionIsLazyTest.php

@@ -29,6 +29,23 @@ public function testChunkIsLazy()
         });
     }
 
+    public function testChunkWhileIsLazy()
+    {
+        $collection = LazyCollection::make(['A', 'A', 'B', 'B', 'C', 'C', 'C']);
+
+        $this->assertDoesNotEnumerateCollection($collection, function ($collection) {
+            $collection->chunkWhile(function ($current, $key, $chunk) {
+                return $current === $chunk->last();
+            });
+        });
+
+        $this->assertEnumeratesCollection($collection, 7, function ($collection) {
+            $collection->chunkWhile(function ($current, $key, $chunk) {
+                return $current === $chunk->last();
+            })->take(7)->all();
+        });
+    }
+
     public function testCollapseIsLazy()
     {
         $collection = LazyCollection::make([