[optional_arg]

fix #1

Author: justinmk

grammar.js

@@ -64,6 +64,7 @@ module.exports = grammar({
         $.taglink,
         $.codespan,
         $.argument,
+        $.optional_arg,
         $.keycode,
         $.note,
       ),
@@ -236,8 +237,10 @@ module.exports = grammar({
     taglink: ($) => _word($, prec(1, /[^|\n\t ]+/), '|', '|'),
     // Inline code (may contain whitespace!): `foo bar`
     codespan: ($) => _word($, /[^``\n]+/, '`', '`'),
-    // Argument: {arg} (no whitespace allowed)
+    // Argument: {arg} (no whitespace allowed), also {arg}? for LuaLS-style optional args.
     argument: ($) => seq(_word($, /[^}\n\t ]+/, '{', '}'), optional(token.immediate('?'))),
+    // Optional argument: [arg] (no whitespace allowed)
+    optional_arg: ($) => _word($, /[^\]\n\t ]+/, '[', ']'),
   },
 });
 

test/corpus/arguments.txt test/corpus/argument.txttest/corpus/arguments.txt renamed to test/corpus/argument.txt

@@ -123,10 +123,8 @@ nvim_buf_detach_event[{buf}]
       (word))
     (line
       (word)
-      (word)
-      (argument
-        (word))
-      (word))))
+      (optional_arg
+        (word)))))
 
 ================================================================================
 NOT an argument

test/corpus/argument_optional.txt

@@ -0,0 +1,40 @@
+================================================================================
+optional [argument]
+================================================================================
+:ar[gs]! [++opt] [+cmd] {arglist}			*:args_f!*
+:[count]arge[dit][!] [++opt] [+cmd] {name} ..
+
+
+--------------------------------------------------------------------------------
+
+(help_file
+  (block
+    (line
+      (word)
+      (optional_arg
+        (word))
+      (word)
+      (optional_arg
+        (word))
+      (optional_arg
+        (word))
+      (argument
+        (word))
+      (tag
+        (word)))
+    (line
+      (word)
+      (optional_arg
+        (word))
+      (word)
+      (optional_arg
+        (word))
+      (optional_arg
+        (word))
+      (optional_arg
+        (word))
+      (optional_arg
+        (word))
+      (argument
+        (word))
+      (word))))

test/corpus/codeblock.txt

@@ -402,8 +402,8 @@ codeblock stop and start on same line
     (line
       (word)
       (word)
-      (word)
-      (word))
+      (optional_arg
+        (word)))
     (line
       (argument
         (word))))

test/corpus/taglink.txt

@@ -56,8 +56,8 @@ Hello |world| hello
       (taglink
         (word))
       (word)
-      (word)
-      (word)
+      (optional_arg
+        (word))
       (word))
     (line
       (taglink

test/corpus/url.txt

@@ -54,11 +54,9 @@ markdown: [https://neovim.io/doc/user/#yay](https://neovim.io/doc/user/#yay).
       (word))
     (line
       (word)
-      (word)
-      (url
+      (optional_arg
         (word))
       (word)
-      (word)
       (url
         (word))
       (word))))