feat: support headlines

Author: vigoux

corpus/headline.txt

@@ -0,0 +1,18 @@
+================================================================================
+Simple headline
+================================================================================
+
+==============================================================================
+Headline                                                             *headline*
+
+Text
+
+--------------------------------------------------------------------------------
+
+(help_file
+  (headline
+    (word)
+    (tag
+      (word)))
+  (line
+    (word)))

grammar.js

@@ -2,19 +2,20 @@ module.exports = grammar({
   name: 'help', // The actual language name is help
 
   extras: ($) => [/[\t ]/],
-  conflicts: ($) => [
-    [$._atom, $.column_name],
-  ],
+  conflicts: ($) => [[$._atom, $.column_name]],
 
-  externals: ($) => [
-    $.code_block
-  ],
+  externals: ($) => [$.code_block],
 
   rules: {
-    help_file: ($) => repeat1(choice($.line, '\n', $.column_heading)),
-
-    header: ($) => seq($.tag),
+    help_file: ($) => repeat1(choice($.line, '\n', $.column_heading, $.headline)),
 
+    headline: ($) =>
+      seq(
+        field('delimiter', choice(/===.*===/, /---.*---/)),
+        '\n',
+        seq(repeat1($.word), $.tag),
+        '\n',
+      ),
     line: ($) => prec.right(seq(repeat1($._atom), optional('\n'))),
 
     _atom: ($) => choice($.word, $.tag, $.code_block),

src/grammar.json

@@ -17,16 +17,57 @@
           {
             "type": "SYMBOL",
             "name": "column_heading"
+          },
+          {
+            "type": "SYMBOL",
+            "name": "headline"
           }
         ]
       }
     },
-    "header": {
+    "headline": {
       "type": "SEQ",
       "members": [
         {
-          "type": "SYMBOL",
-          "name": "tag"
+          "type": "FIELD",
+          "name": "delimiter",
+          "content": {
+            "type": "CHOICE",
+            "members": [
+              {
+                "type": "PATTERN",
+                "value": "===.*==="
+              },
+              {
+                "type": "PATTERN",
+                "value": "---.*---"
+              }
+            ]
+          }
+        },
+        {
+          "type": "STRING",
+          "value": "\n"
+        },
+        {
+          "type": "SEQ",
+          "members": [
+            {
+              "type": "REPEAT1",
+              "content": {
+                "type": "SYMBOL",
+                "name": "word"
+              }
+            },
+            {
+              "type": "SYMBOL",
+              "name": "tag"
+            }
+          ]
+        },
+        {
+          "type": "STRING",
+          "value": "\n"
         }
       ]
     },

src/node-types.json

@@ -44,6 +44,25 @@
       ]
     }
   },
+  {
+    "type": "headline",
+    "named": true,
+    "fields": {},
+    "children": {
+      "multiple": true,
+      "required": true,
+      "types": [
+        {
+          "type": "tag",
+          "named": true
+        },
+        {
+          "type": "word",
+          "named": true
+        }
+      ]
+    }
+  },
   {
     "type": "help_file",
     "named": true,
@@ -56,6 +75,10 @@
           "type": "column_heading",
           "named": true
         },
+        {
+          "type": "headline",
+          "named": true
+        },
         {
           "type": "line",
           "named": true