[Bug-68] added support for length on array

+ added token value check for length only if named key doesn't exist
+ updated test case to show it working
+ bonus: fixed test case for working length checks on script expressions

Author: Luke Jones

src/Filters/IndexFilter.php

@@ -41,6 +41,12 @@ public function filter($collection): array
             return AccessHelper::arrayValues($collection);
         }
 
+        if ($this->token->value === 'length') {
+            return [
+                count($collection),
+            ];
+        }
+
         return [];
     }
 }

tests/QueryTest.php

@@ -808,7 +808,7 @@ public function queryDataProvider(): array
                 'dot_notation_with_key_named_length_on_array',
                 '$.length',
                 '[4,5,6]',
-                '[]'
+                '[3]'
             ],
             [ // data set #114
                 'dot_notation_with_key_named_null',
@@ -1454,7 +1454,7 @@ public function queryDataProvider(): array
                 'script_expression',
                 '$[(@.length-1)]',
                 '["first","second","third","forth","fifth"]',
-                ''
+                'fifth'
             ],
             [ // data set #214
                 'union',