Commit 958da7ff authored by Jackson Ray Hamilton's avatar Jackson Ray Hamilton

Add JSX indentation via js-jsx-mode. (Bug#21799)

* progmodes/js.el: Add JSX indentation support.
(js-jsx-mode): New functions.
parent 65a3808f
......@@ -911,6 +911,9 @@ alists, hash-table and arrays. All functions are prefixed with
** The `thunk' library provides functions and macros to control the
evaluation of forms.
** js-jsx-mode (a minor variant of js-mode) provides indentation
support for JSX, an XML-like syntax extension to ECMAScript
* Incompatible Lisp Changes in Emacs 25.1
......@@ -52,6 +52,7 @@
(require 'imenu)
(require 'moz nil t)
(require 'json nil t)
(require 'sgml-mode)
(require 'cl-lib)
......@@ -1998,6 +1999,193 @@ indentation is aligned to that column."
(+ js-indent-level js-expr-indent-offset))
(t 0))))
;;; JSX Indentation
(defsubst js--jsx-find-before-tag ()
"Find where JSX starts.
Assume JSX appears in the following instances:
- Inside parentheses, when returned or as the first argument
to a function, and after a newline
- When assigned to variables or object properties, but only
on a single line
- As the N+1th argument to a function
This is an optimized version of (re-search-backward \"[(,]\n\"
nil t), except set point to the end of the match. This logic
executes up to the number of lines in the file, so it should be
really fast to reduce that impact."
(let (pos)
(while (and (> (point) (point-min))
(not (progn
(end-of-line 0)
(when (or (eq (char-before) 40) ; (
(eq (char-before) 44)) ; ,
(setq pos (1- (point))))))))
(defconst js--jsx-end-tag-re
(concat "</" sgml-name-re ">\\|/>")
"Find the end of a JSX element.")
(defconst js--jsx-after-tag-re "[),]"
"Find where JSX ends.
This complements the assumption of where JSX appears from
`js--jsx-before-tag-re', which see.")
(defun js--jsx-indented-element-p ()
"Determine if/how the current line should be indented as JSX.
Return `first' for the first JSXElement on its own line.
Return `nth' for subsequent lines of the first JSXElement.
Return `expression' for an embedded JS expression.
Return `after' for anything after the last JSXElement.
Return nil for non-JSX lines.
Currently, JSX indentation supports the following styles:
- Single-line elements (indented like normal JS):
var element = <div></div>;
- Multi-line elements (enclosed in parentheses):
function () {
return (
- Function arguments:
(let ((current-pos (point))
(current-line (line-number-at-pos))
before-tag-pos before-tag-line
tag-start-pos tag-start-line
tag-end-pos tag-end-line
parens paren type)
;; Determine if we're inside a jsx element
(while (and (not tag-start-pos)
(setq last-pos (js--jsx-find-before-tag)))
(while (forward-comment 1))
(when (= (char-after) 60) ; <
(setq before-tag-pos last-pos
tag-start-pos (point)))
(goto-char last-pos))
(setq before-tag-line (line-number-at-pos before-tag-pos)
tag-start-line (line-number-at-pos tag-start-pos))
;; A "before" line which also starts an element begins with js, so
;; indent it like js
(> current-line before-tag-line)
;; Only indent the jsx lines like jsx
(>= current-line tag-start-line)))
;; Analyze bounds if there are any
(while (and (not tag-end-pos)
(setq last-pos (re-search-forward js--jsx-end-tag-re nil t)))
(while (forward-comment 1))
(when (looking-at js--jsx-after-tag-re)
(setq tag-end-pos last-pos)))
(setq tag-end-line (line-number-at-pos tag-end-pos)
after-tag-line (line-number-at-pos after-tag-line))
(or (and
;; Ensure we're actually within the bounds of the jsx
(<= current-line tag-end-line)
;; An "after" line which does not end an element begins with
;; js, so indent it like js
(<= current-line after-tag-line))
;; Handle another case where there could be e.g. comments after
;; the element
(> current-line tag-end-line)
(< current-line after-tag-line)
(setq type 'after))))
;; They may not be any bounds (yet)
;; Check if we're inside an embedded multi-line js expression
((not type)
(goto-char current-pos)
(setq parens (nth 9 (syntax-ppss)))
(while (and parens (not type))
(setq paren (car parens))
((and (>= paren tag-start-pos)
;; Curly bracket indicates the start of an embedded expression
(= (char-after paren) 123) ; {
;; The first line of the expression is indented like sgml
(> current-line (line-number-at-pos paren))
;; Check if within a closing curly bracket (if any)
;; (exclusive, as the closing bracket is indented like sgml)
(goto-char paren)
(ignore-errors (let (forward-sexp-function)
(< current-line (line-number-at-pos)))
;; Indicate this guy will be indented specially
(setq type 'expression))
(t (setq parens (cdr parens)))))
;; Indent the first jsx thing like js so we can indent future jsx things
;; like sgml relative to the first thing
((= current-line tag-start-line) 'first)
(defmacro js--as-sgml (&rest body)
"Execute BODY as if in sgml-mode."
`(with-syntax-table sgml-mode-syntax-table
(let (forward-sexp-function
(defun js--expression-in-sgml-indent-line ()
"Indent the current line as JavaScript or SGML (whichever is farther)."
(let* (indent-col
(savep (point))
;; Don't whine about errors/warnings when we're indenting.
;; This has to be set before calling parse-partial-sexp below.
(inhibit-point-motion-hooks t)
(parse-status (save-excursion
(syntax-ppss (point-at-bol)))))
;; Don't touch multiline strings.
(unless (nth 3 parse-status)
(setq indent-col (save-excursion
(if (>= (point) savep) (setq savep nil))
(js--as-sgml (sgml-calculate-indent))))
(if (null indent-col)
;; Use whichever indentation column is greater, such that the sgml
;; column is effectively a minimum
(setq indent-col (max (js--proper-indentation parse-status)
(+ indent-col js-indent-level)))
(if savep
(save-excursion (indent-line-to indent-col))
(indent-line-to indent-col))))))
(defun js-indent-line ()
"Indent the current line as JavaScript."
......@@ -2008,6 +2196,25 @@ indentation is aligned to that column."
(indent-line-to (js--proper-indentation parse-status))
(when (> offset 0) (forward-char offset)))))
(defun js-jsx-indent-line ()
"Indent the current line as JSX (with SGML offsets).
i.e., customize JSX element indentation with `sgml-basic-offset',
`sgml-attribute-offset' et al."
(let ((indentation-type (js--jsx-indented-element-p)))
((eq indentation-type 'expression)
((or (eq indentation-type 'first)
(eq indentation-type 'after))
;; Don't treat this first thing as a continued expression (often a "<" or
;; ">" causes this misinterpretation)
(cl-letf (((symbol-function #'js--continued-expression-p) 'ignore))
((eq indentation-type 'nth)
(js--as-sgml (sgml-indent-line)))
(t (js-indent-line)))))
;;; Filling
(defvar js--filling-paragraph nil)
......@@ -3566,6 +3773,20 @@ If one hasn't been set, or if it's stale, prompt for a new one."
;;(syntax-propertize (point-max))
(define-derived-mode js-jsx-mode js-mode "JSX"
"Major mode for editing JSX.
To customize the indentation for this mode, set the SGML offset
variables (`sgml-basic-offset', `sgml-attribute-offset' et al)
locally, like so:
(defun set-jsx-indentation ()
(setq-local sgml-basic-offset js-indent-level))
(add-hook 'js-jsx-mode-hook #'set-jsx-indentation)"
:group 'js
(setq-local indent-line-function #'js-jsx-indent-line))
;;;###autoload (defalias 'javascript-mode 'js-mode)
(eval-after-load 'folding
// -*- mode: js-jsx; -*-
var foo = <div></div>;
return (
a: 1
return (
// Sneaky!
return (
// Sneaky!
a: 1
return (
{ () {
return {
a: 1
return (
<div attribute={ () {
return {
a: 1
return {
a: 1
return {
a: 1
// Local Variables:
// indent-tabs-mode: nil
// js-indent-level: 2
// End:
// The following test has intentionally unclosed elements and should
// be placed below all other tests to prevent awkward indentation.
return (
{ () {
return {
a: 1
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