[PATCH] Update js-mode function heading regexes

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[PATCH] Update js-mode function heading regexes

Adam Niederer
Hello,

I've modified the js-mode function heading regular expressions to accept
some modern additions to JavaScript. This causes function names to be
highlighted in more cases, and makes js-beginning-of-defun and
js-end-of-defun more consistent. The changelog and behavioral changes
are as follows:

* js--function-heading-1-re - Accept "async function foo" as well as
"function foo". This should only affect highlighting.

* js--function-heading-2-re - Accept any character before the beginning
of a function in an object. This causes the function's name to be
correctly highlighted.

Pre-patch, beginning-of-defun (C-M-a) with the point in location 1
(below) will place point at the beginning of the function keyword,
whereas at location 2 it will place point at the beginning of "bur".

Post-patch, beginning-of-defun at location 1 will place point at the
beginning of "foo", and at location 2 it will place point at the
beginning of "bur"

{ foo: function() {<point location 1>}
  bur: function() {<point location 2>} }

* js--function-heading-3-re - Accept let, const, and async anonymous
functions

Pre-patch, beginning-of-defun (C-M-a) with the point in location 1
(below) will place point at the beginning of "x", whereas at locations
2, 3 and 4, it will place point at the beginning of the respective
function keywords.

Post-patch, beginning-of-defun (C-M-a) with the point in location 1
(below) will place point at the beginning of "x", whereas at location 2,
3 and 4, it will place point at the beginning of "y", "z" and "w",
respectively.

var x = function() {<point location 1>}
var y = async function() {<point location 2>}

let z = function() {<point location 3>}
let w = async function() {<point location 4>}

Below is the file I used to test these changes. make check is failing
for me, but it looks like the failing tests are unrelated (filenotify &
inotify).

This is my first contribution via a mailing list, so please let me know
if I'm missing anything :).

-Adam

{ foo: function() {}
  bar: function() {} }

[{ foo: function() {}
   bar: function() {} }]

let x = [{ foo: function() {}
           bar: function() {} }]

function foo() {}
async function bar() {}

var x = function() {}
var x = async function() {}

let x = function() {}
let x = async function() {}

const x = function() {}
const x = async function() {}

diff --git a/lisp/progmodes/js.el b/lisp/progmodes/js.el
index bae9e52bf0..126181f5bb 100644
--- a/lisp/progmodes/js.el
+++ b/lisp/progmodes/js.el
@@ -250,20 +250,20 @@ js--available-frameworks
 
 (defconst js--function-heading-1-re
   (concat
-   "^\\s-*function\\(?:\\s-\\|\\*\\)+\\(" js--name-re "\\)")
+   "^\\s-*\\(?:async\\s-+\\)?function\\(?:\\s-\\|\\*\\)+\\("
js--name-re "\\)")
   "Regexp matching the start of a JavaScript function header.
 Match group 1 is the name of the function.")
 
 (defconst js--function-heading-2-re
   (concat
-   "^\\s-*\\(" js--name-re "\\)\\s-*:\\s-*function\\_>")
+   "^.*?\\(" js--name-re "\\)\\s-*:\\s-*function\\_>")
   "Regexp matching the start of a function entry in an associative array.
 Match group 1 is the name of the function.")
 
 (defconst js--function-heading-3-re
   (concat
-   "^\\s-*\\(?:var\\s-+\\)?\\(" js--dotted-name-re "\\)"
-   "\\s-*=\\s-*function\\_>")
+   "^\\s-*\\(?:\\(?:var\\|let\\|const\\)\\s-+\\)?\\("
js--dotted-name-re "\\)"
+   "\\s-*=\\s-*\\(?:async\\s-+\\)?function\\_>")
   "Regexp matching a line in the JavaScript form \"var MUMBLE = function\".
 Match group 1 is MUMBLE.")
 


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Re: [PATCH] Update js-mode function heading regexes

Dmitry Gutov
Hi!

On 6/17/17 10:30 AM, Adam Niederer wrote:
> Below is the file I used to test these changes. make check is failing
> for me, but it looks like the failing tests are unrelated (filenotify &
> inotify).

These are manual tests, right? 'make check' doesn't sound relevant.

But we have some automated tests for js.el too. Check out
test/lisp/progmodes/js-tests.el. Maybe these scenarios would be better
coded with ERT.

> This is my first contribution via a mailing list, so please let me know
> if I'm missing anything :).

Not much. Patch submissions via the bug tracker have higher odds of not
being forgotten is they're not applied right away, though.

Thanks for the patch.

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Re: [PATCH] Update js-mode function heading regexes

Adam Niederer
> These are manual tests, right? 'make check' doesn't sound relevant.
> But we have some automated tests for js.el too. Check out
> test/lisp/progmodes/js-tests.el. Maybe these scenarios would be better
> coded with ERT.
The file I included was primarily for visual evaluation of the changes.
Adding some automated tests is a good idea, though, so I've included an
updated patchset below. This also makes js--function-heading-2-re work
on async functions.
> Not much. Patch submissions via the bug tracker have higher odds of
> not being forgotten is they're not applied right away, though.
>
> Thanks for the patch.

Would reposting these changes to bug-gnu-emacs be a good idea?

Thanks a lot,

-Adam

--- a/lisp/progmodes/js.el
+++ b/lisp/progmodes/js.el
@@ -250,20 +250,20 @@ js--available-frameworks
 
 (defconst js--function-heading-1-re
   (concat
-   "^\\s-*function\\(?:\\s-\\|\\*\\)+\\(" js--name-re "\\)")
+   "^\\s-*\\(?:async\\s-+\\)?function\\(?:\\s-\\|\\*\\)+\\("
js--name-re "\\)")
   "Regexp matching the start of a JavaScript function header.
 Match group 1 is the name of the function.")
 
 (defconst js--function-heading-2-re
   (concat
-   "^\\s-*\\(" js--name-re "\\)\\s-*:\\s-*function\\_>")
+   "^.*?\\(" js--name-re "\\)\\s-*:\\s-*\\(?:async\\s-+\\)?function\\_>")
   "Regexp matching the start of a function entry in an associative array.
 Match group 1 is the name of the function.")
 
 (defconst js--function-heading-3-re
   (concat
-   "^\\s-*\\(?:var\\s-+\\)?\\(" js--dotted-name-re "\\)"
-   "\\s-*=\\s-*function\\_>")
+   "^\\s-*\\(?:\\(?:var\\|let\\|const\\)\\s-+\\)?\\("
js--dotted-name-re "\\)"
+   "\\s-*=\\s-*\\(?:async\\s-+\\)?function\\_>")
   "Regexp matching a line in the JavaScript form \"var MUMBLE = function\".
 Match group 1 is MUMBLE.")

diff --git a/test/lisp/progmodes/js-tests.el
b/test/lisp/progmodes/js-tests.el
index 8e1bac10cd..313e2e2e52 100644
--- a/test/lisp/progmodes/js-tests.el
+++ b/test/lisp/progmodes/js-tests.el
@@ -177,6 +177,44 @@
     ;; The bug was a hang.
     (should t)))
 
+(ert-deftest js-mode-highlight-function-names ()
+  "Ensure js--function-heading-1-re and js--function-heading-2-re match all
+possible function declarations and highlight the function names
accordingly."
+  (with-temp-buffer
+    (js-mode)
+    (insert "function foo() {}\n"
+            "async function bar() {}\n"
+            "let x = [{ baz: function() {}\n"
+            "           quux: function() {}\n"
+            "           kek: async function() {}\n"
+            "/**/       bur: async function() {} }]\n")
+    (font-lock-ensure)
+    (dolist (name '("foo" "bar" "baz" "quux" "kek" "bur"))
+      (save-excursion
+        (search-backward name)
+        (should (equal (face-at-point) font-lock-function-name-face))))))
+
+(ert-deftest js-mode-accept-function-bindings ()
+  "Ensure js--function-heading-3-re matches all function declarations
of the
+form (var|let|const) foo = (async)? function."
+  (with-temp-buffer
+    (js-mode)
+    (insert "var foo = async function() {}\n"
+            "const bar = async function() {}\n"
+            "let baz = async function() {}\n"
+            "var quux = function() {}\n"
+            "const kek = function() {}\n"
+            "let bur = function() {}\n")
+    (dolist (name '("foo" "bar" "baz" "quux" "kek" "bur"))
+      ;; re-search-backward will throw if one the strings doesn't match.
+      (re-search-backward js--function-heading-3-re))
+    ;; Ensure we have exactly six matches
+    (should-error (re-search-backward js--function-heading-3-re))))
+
 (provide 'js-tests)
 
 ;;; js-tests.el ends here


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