Proposal for a fix of #580.

Author: niconoe-

src/Components/AlterOperation.php

@@ -131,7 +131,10 @@ class AlterOperation extends Component
         'BY' => 2,
         'FOREIGN' => 2,
         'FULLTEXT' => 2,
-        'KEY' => 2,
+        'KEY' => [
+            2,
+            'var',
+        ],
         'KEYS' => 2,
         'PARTITION' => 2,
         'PARTITION BY' => 2,

tests/data/bugs/gh317.out

@@ -209,19 +209,15 @@
                             "@type": "PhpMyAdmin\\SqlParser\\Components\\OptionsArray",
                             "options": {
                                 "1": "ADD",
-                                "2": "KEY"
+                                "2": {
+                                    "name": "KEY",
+                                    "equals": false,
+                                    "expr": "`IDX_REPAIR`",
+                                    "value": "IDX_REPAIR"
+                                }
                             }
                         },
-                        "field": {
-                            "@type": "PhpMyAdmin\\SqlParser\\Components\\Expression",
-                            "database": null,
-                            "table": null,
-                            "column": "IDX_REPAIR",
-                            "expr": "`IDX_REPAIR`",
-                            "alias": null,
-                            "function": null,
-                            "subquery": null
-                        },
+                        "field": null,
                         "partitions": null,
                         "unknown": [
                             {

tests/data/parser/parseAlter.out

@@ -327,19 +327,15 @@
                             "@type": "PhpMyAdmin\\SqlParser\\Components\\OptionsArray",
                             "options": {
                                 "1": "ADD",
-                                "2": "KEY"
+                                "2": {
+                                    "name": "KEY",
+                                    "equals": false,
+                                    "expr": "`idx_actor_last_name`",
+                                    "value": "idx_actor_last_name"
+                                }
                             }
                         },
-                        "field": {
-                            "@type": "PhpMyAdmin\\SqlParser\\Components\\Expression",
-                            "database": null,
-                            "table": null,
-                            "column": "idx_actor_last_name",
-                            "expr": "`idx_actor_last_name`",
-                            "alias": null,
-                            "function": null,
-                            "subquery": null
-                        },
+                        "field": null,
                         "partitions": null,
                         "unknown": [
                             {

tests/data/parser/parsephpMyAdminExport1.out

@@ -5480,19 +5480,15 @@
                                     "@type": "PhpMyAdmin\\SqlParser\\Components\\OptionsArray",
                                     "options": {
                                         "1": "ADD",
-                                        "2": "KEY"
+                                        "2": {
+                                            "name": "KEY",
+                                            "equals": false,
+                                            "expr": "`INDEX_totalTime`",
+                                            "value": "INDEX_totalTime"
+                                        }
                                     }
                                 },
-                                "field": {
-                                    "@type": "PhpMyAdmin\\SqlParser\\Components\\Expression",
-                                    "database": null,
-                                    "table": null,
-                                    "column": "INDEX_totalTime",
-                                    "expr": "`INDEX_totalTime`",
-                                    "alias": null,
-                                    "function": null,
-                                    "subquery": null
-                                },
+                                "field": null,
                                 "partitions": null,
                                 "unknown": [
                                     {