feat: keycodes, special

close #1

corpus/text.txt

@@ -2,6 +2,8 @@
 simple file with text
 ================================================================================
 Simple text
+<Del> <CSI> <C-S-x> <C-x> <M-^> <x-y>
+CTRL-{char} ctr-z CTRL-SHIFT-\ CTRL-+ CTRL-Break ALT-?
 
 
 --------------------------------------------------------------------------------
@@ -10,7 +12,21 @@ Simple text
   (block
     (line
       (word)
-      (word))))
+      (word))
+    (line
+      (keycode)
+      (keycode)
+      (keycode)
+      (keycode)
+      (keycode)
+      (keycode))
+    (line
+      (keycode)
+      (word)
+      (keycode)
+      (keycode)
+      (keycode)
+      (keycode))))
 
 ================================================================================
 multiline text

grammar.js

@@ -1,3 +1,9 @@
+// https://tree-sitter.github.io/tree-sitter/creating-parsers#conflicting-tokens
+// - Match Specificity: Tree-sitter will prefer a token that is specified in
+//   the grammar as a String instead of a RegExp.
+// - Rule Order: Tree-sitter will prefer the token that appears earlier in the
+//   grammar.
+//
 // https://tree-sitter.github.io/tree-sitter/creating-parsers
 // - Rules starting with underscore are hidden in the syntax tree.
 
@@ -50,6 +56,7 @@ module.exports = grammar({
         $.taglink,
         $.codespan,
         $.argument,
+        $.keycode,
       ),
 
     // Explicit special cases: these are plaintext, not errors.
@@ -71,6 +78,17 @@ module.exports = grammar({
       /\w+\(/,
     ),
 
+    keycode: () => choice(
+      /<[-a-zA-Z0-9_]+>/,
+      /<[SCMAD]-.>/,
+      /CTRL-./,
+      /CTRL-SHIFT-./,
+      /CTRL-(Break|PageUp|PageDown|Insert|Del)/,
+      /CTRL-\{char\}/,
+      /META-./,
+      /ALT-./,
+    ),
+
     // First part (minus tags) of h3 or column_heading.
     uppercase_name: () => seq(
       token.immediate(_uppercase_word),  // No whitespace before heading.