Merge branch '8.x'

# Conflicts:
#	CHANGELOG-6.x.md
#	CHANGELOG-8.x.md
#	composer.json
#	src/Illuminate/Database/Schema/Grammars/MySqlGrammar.php
#	src/Illuminate/Database/Schema/Grammars/SQLiteGrammar.php
#	src/Illuminate/Foundation/Application.php
#	src/Illuminate/Foundation/Providers/ArtisanServiceProvider.php

Author: driesvints

Collection.php

@@ -959,6 +959,22 @@ public function shuffle($seed = null)
         return new static(Arr::shuffle($this->items, $seed));
     }
 
+    /**
+     * Create chunks representing a "sliding window" view of the items in the collection.
+     *
+     * @param  int  $size
+     * @param  int  $step
+     * @return static
+     */
+    public function sliding($size = 2, $step = 1)
+    {
+        $chunks = floor(($this->count() - $size) / $step) + 1;
+
+        return static::times($chunks, function ($number) use ($size, $step) {
+            return $this->slice(($number - 1) * $step, $size);
+        });
+    }
+
     /**
      * Skip the first {$count} items.
      *

LazyCollection.php

@@ -920,6 +920,45 @@ public function shuffle($seed = null)
         return $this->passthru('shuffle', func_get_args());
     }
 
+    /**
+     * Create chunks representing a "sliding window" view of the items in the collection.
+     *
+     * @param  int  $size
+     * @param  int  $step
+     * @return static
+     */
+    public function sliding($size = 2, $step = 1)
+    {
+        return new static(function () use ($size, $step) {
+            $iterator = $this->getIterator();
+
+            $chunk = [];
+
+            while ($iterator->valid()) {
+                $chunk[$iterator->key()] = $iterator->current();
+
+                if (count($chunk) == $size) {
+                    yield tap(new static($chunk), function () use (&$chunk, $step) {
+                        $chunk = array_slice($chunk, $step, null, true);
+                    });
+
+                    // If the $step between chunks is bigger than each chunk's $size
+                    // we will skip the extra items (which should never be in any
+                    // chunk) before we continue to the next chunk in the loop.
+                    if ($step > $size) {
+                        $skip = $step - $size;
+
+                        for ($i = 0; $i < $skip && $iterator->valid(); $i++) {
+                            $iterator->next();
+                        }
+                    }
+                }
+
+                $iterator->next();
+            }
+        });
+    }
+
     /**
      * Skip the first {$count} items.
      *