From c7e42b8e9624d193be7687d8fb8ce33a946ba336 Mon Sep 17 00:00:00 2001
From: Max Brunsfeld <maxbrunsfeld@gmail.com>
Date: Thu, 1 Mar 2018 09:53:10 -0800
Subject: [PATCH] Add special lexing for regexes after `=~`

---
 corpus/expressions.txt | 33 +++++++++++++++++++++++----------
 grammar.js             | 20 ++++++++++++++++----
 2 files changed, 39 insertions(+), 14 deletions(-)

diff --git a/corpus/expressions.txt b/corpus/expressions.txt
index 008d787..9cec1aa 100644
--- a/corpus/expressions.txt
+++ b/corpus/expressions.txt
@@ -18,22 +18,35 @@ Words with special characters
 echo {o[k]}
 echo }}}
 echo ]]] ===
-[[ "35d8b" =~ ^[0-9a-fA-F] ]] || echo {nomatch}
 
 ---
 
 (program
   (command (command_name (word)) (concatenation (word) (word)))
   (command (command_name (word)) (word))
-  (command (command_name (word)) (word) (word))
-  (list
-    (bracket_command
-      (string)
-      (word)
-      (concatenation (word) (word)))
-    (command
-      (command_name (word))
-      (concatenation (word)))))
+  (command (command_name (word)) (word) (word)))
+
+=============================
+The regex operator
+=============================
+
+[[ "35d8b" =~ ^[0-9a-fA-F] ]]
+[[ $CMD =~ (^|;)update_terminal_cwd($|;) ]]
+[[ ! " ${completions[*]} " =~ " $alias_cmd " ]]
+
+---
+
+(program
+  (bracket_command
+    (string)
+    (regex))
+  (bracket_command
+    (simple_expansion (variable_name))
+    (regex))
+  (bracket_command
+    (word)
+    (string (expansion (subscript (variable_name) (word))))
+    (string (simple_expansion (variable_name)))))
 
 =============================
 Simple variable expansions
diff --git a/grammar.js b/grammar.js
index 2d89990..784713a 100644
--- a/grammar.js
+++ b/grammar.js
@@ -179,10 +179,20 @@ module.exports = grammar({
       $._statement
     )),
 
-    bracket_command: $ => choice(
-      seq('[', repeat1($._expression), ']'),
-      seq('[[', repeat1($._expression), ']]')
-    ),
+    bracket_command: $ => {
+      const contents = repeat1(choice(
+        $._expression,
+        seq('=~', choice(
+          $.regex,
+          $._expression
+        ))
+      ))
+
+      return choice(
+        seq('[', contents, ']'),
+        seq('[[', contents, ']]')
+      )
+    },
 
     // Commands
 
@@ -383,6 +393,8 @@ module.exports = grammar({
       seq('\\', noneOf('\\s'))
     ))),
 
+    regex: $ => /\S+/,
+
     _terminator: $ => choice(';', ';;', '\n', '&')
   }
 });