grammar: move constraint to hidden rule

grammar.js

@@ -160,7 +160,7 @@ module.exports = grammar({
 
     conflict_target: ($) =>
       choice(
-        seq(kw("on"), kw("constraint"), $.identifier),
+        seq(kw("on"), $._constraint, $.identifier),
         seq("(", commaSep($._value_expression), ")")
       ),
 
@@ -298,7 +298,7 @@ module.exports = grammar({
         ),
         seq(
           kw("drop"),
-          kw("constraint"),
+          $._constraint,
           optional($.if_exists),
           $.identifier,
           optional($.alter_table_fk_ref_action)
@@ -330,7 +330,7 @@ module.exports = grammar({
 
     table_constraint: ($) =>
       seq(
-        optional(seq(kw("constraint"), $.identifier)),
+        optional(seq($._constraint, $.identifier)),
         $.table_constraint_ty,
         optional($.constraint_when)
       ),
@@ -379,20 +379,18 @@ module.exports = grammar({
 
     alter_column_type: ($) =>
       seq($._type, optional(seq(kw("using"), $._value_expression))),
+
     alter_table_fk_ref_action: ($) => choice(kw("restrict"), kw("cascade")),
+
     table_column_item: ($) =>
       seq($.identifier, $._type, repeat($.column_constraint)),
 
     column_constraint: ($) =>
-      choice(
       seq(
-          kw("constraint"),
+        optional(seq($._constraint, $.identifier)),
-          $.identifier,
         $.column_constraint_ty,
         optional($.constraint_when)
       ),
-        seq($.column_constraint_ty, optional($.constraint_when))
-      ),
 
     column_constraint_ty: ($) =>
       choice(
@@ -413,9 +411,12 @@ module.exports = grammar({
         kw("to"),
         $.identifier
       ),
+
     alter_table_rename_constraint: ($) =>
-      seq(kw("rename"), kw("constraint"), $.identifier, kw("to"), $.identifier),
+      seq(kw("rename"), $._constraint, $.identifier, kw("to"), $.identifier),
+
     alter_table_rename_table: ($) => seq(kw("rename"), kw("to"), $.identifier),
+
     alter_table_change_schema: ($) =>
       seq(kw("set"), kw("schema"), $.identifier),
 
@@ -517,7 +518,7 @@ module.exports = grammar({
     create_trigger_statement: ($) =>
       seq(
         kw("create"),
-        optional(kw("constraint")),
+        optional($._constraint),
         kw("trigger"),
         $.identifier,
         $.trigger_when,
@@ -1083,5 +1084,8 @@ module.exports = grammar({
     _identifier: ($) => /[a-zA-Z0-9_]+(\.?[a-zA-Z0-9_]+)*/,
     //                                ^
     //                                |- we dont want to match consecutive dots, e.g: 1..2 consists of 3 tokens
+
+    //--------------------------
+    _constraint: ($) => kw("constraint"),
   },
 });

src/grammar.json

@@ -955,8 +955,8 @@
               "value": "[oO][nN]"
             },
             {
-              "type": "PATTERN",
+              "type": "SYMBOL",
-              "value": "[cC][oO][nN][sS][tT][rR][aA][iI][nN][tT]"
+              "name": "_constraint"
             },
             {
               "type": "SYMBOL",
@@ -1919,8 +1919,8 @@
               "value": "[dD][rR][oO][pP]"
             },
             {
-              "type": "PATTERN",
+              "type": "SYMBOL",
-              "value": "[cC][oO][nN][sS][tT][rR][aA][iI][nN][tT]"
+              "name": "_constraint"
             },
             {
               "type": "CHOICE",
@@ -2153,8 +2153,8 @@
               "type": "SEQ",
               "members": [
                 {
-                  "type": "PATTERN",
+                  "type": "SYMBOL",
-                  "value": "[cC][oO][nN][sS][tT][rR][aA][iI][nN][tT]"
+                  "name": "_constraint"
                 },
                 {
                   "type": "SYMBOL",
@@ -2488,18 +2488,28 @@
       ]
     },
     "column_constraint": {
+      "type": "SEQ",
+      "members": [
+        {
           "type": "CHOICE",
           "members": [
             {
               "type": "SEQ",
               "members": [
                 {
-              "type": "PATTERN",
+                  "type": "SYMBOL",
-              "value": "[cC][oO][nN][sS][tT][rR][aA][iI][nN][tT]"
+                  "name": "_constraint"
                 },
                 {
                   "type": "SYMBOL",
                   "name": "identifier"
+                }
+              ]
+            },
+            {
+              "type": "BLANK"
+            }
+          ]
         },
         {
           "type": "SYMBOL",
@@ -2519,29 +2529,6 @@
         }
       ]
     },
-        {
-          "type": "SEQ",
-          "members": [
-            {
-              "type": "SYMBOL",
-              "name": "column_constraint_ty"
-            },
-            {
-              "type": "CHOICE",
-              "members": [
-                {
-                  "type": "SYMBOL",
-                  "name": "constraint_when"
-                },
-                {
-                  "type": "BLANK"
-                }
-              ]
-            }
-          ]
-        }
-      ]
-    },
     "column_constraint_ty": {
       "type": "CHOICE",
       "members": [
@@ -2660,8 +2647,8 @@
           "value": "[rR][eE][nN][aA][mM][eE]"
         },
         {
-          "type": "PATTERN",
+          "type": "SYMBOL",
-          "value": "[cC][oO][nN][sS][tT][rR][aA][iI][nN][tT]"
+          "name": "_constraint"
         },
         {
           "type": "SYMBOL",
@@ -3457,8 +3444,8 @@
           "type": "CHOICE",
           "members": [
             {
-              "type": "PATTERN",
+              "type": "SYMBOL",
-              "value": "[cC][oO][nN][sS][tT][rR][aA][iI][nN][tT]"
+              "name": "_constraint"
             },
             {
               "type": "BLANK"
@@ -7044,6 +7031,10 @@
     "_identifier": {
       "type": "PATTERN",
       "value": "[a-zA-Z0-9_]+(\\.?[a-zA-Z0-9_]+)*"
+    },
+    "_constraint": {
+      "type": "PATTERN",
+      "value": "[cC][oO][nN][sS][tT][rR][aA][iI][nN][tT]"
     }
   },
   "extras": [