Commit 50239082 authored by Tom Tromey's avatar Tom Tromey
Browse files

Add chained indentation to js-mode

Bug#20896
* lisp/progmodes/js.el (js-chain-indent): New variable.
(js--skip-term-backward, js--skip-terms-backward)
(js--chained-expression-p): New functions.
(js--proper-indentation): Call js--chained-expression-p.
* test/manual/indent/js-chain.js: New file.
* test/manual/indent/js.js: Add (non-)chained indentation test.
parent b47f9721
......@@ -552,6 +552,20 @@ don't indent the first one's initializer; otherwise, indent it.
:safe 'symbolp
:group 'js)
(defcustom js-chain-indent nil
"Use \"chained\" indentation.
Chained indentation applies when the current line starts with \".\".
If the previous expression also contains a \".\" at the same level,
then the \".\"s will be lined up:
let x = svg.mumble()
.chained;
"
:version "26.1"
:type 'boolean
:safe 'booleanp
:group 'js)
;;; KeyMap
(defvar js-mode-map
......@@ -1808,6 +1822,63 @@ This performs fontification according to `js--class-styles'."
(and (progn (backward-char)
(not (looking-at "+\\+\\|--\\|/[/*]"))))))))))
(defun js--skip-term-backward ()
"Skip a term before point; return t if a term was skipped."
(let ((term-skipped nil))
;; Skip backward over balanced parens.
(let ((progress t))
(while progress
(setq progress nil)
;; First skip whitespace.
(skip-syntax-backward " ")
;; Now if we're looking at closing paren, skip to the opener.
;; This doesn't strictly follow JS syntax, in that we might
;; skip something nonsensical like "()[]{}", but it is enough
;; if it works ok for valid input.
(when (memq (char-before) '(?\] ?\) ?\}))
(setq progress t term-skipped t)
(backward-list))))
;; Maybe skip over a symbol.
(let ((save-point (point)))
(if (and (< (skip-syntax-backward "w_") 0)
(looking-at js--name-re))
;; Skipped.
(progn
(setq term-skipped t)
(skip-syntax-backward " "))
;; Did not skip, so restore point.
(goto-char save-point)))
(when (and term-skipped (> (point) (point-min)))
(backward-char)
(eq (char-after) ?.))))
(defun js--skip-terms-backward ()
"Skip any number of terms backward.
Move point to the earliest \".\" without changing paren levels.
Returns t if successful, nil if no term was found."
(when (js--skip-term-backward)
;; Found at least one.
(let ((last-point (point)))
(while (js--skip-term-backward)
(setq last-point (point)))
(goto-char last-point)
t)))
(defun js--chained-expression-p ()
"A helper for js--proper-indentation that handles chained expressions.
A chained expression is when the current line starts with '.' and the
previous line also has a '.' expression.
This function returns the indentation for the current line if it is
a chained expression line; otherwise nil.
This should only be called while point is at the start of the line's content,
as determined by `back-to-indentation'."
(when js-chain-indent
(save-excursion
(when (and (eq (char-after) ?.)
(js--continued-expression-p)
(js--find-newline-backward)
(js--skip-terms-backward))
(current-column)))))
(defun js--end-of-do-while-loop-p ()
"Return non-nil if point is on the \"while\" of a do-while statement.
......@@ -1984,6 +2055,7 @@ indentation is aligned to that column."
;; At or after the first loop?
(>= (point) beg)
(js--array-comp-indentation bracket beg))))
((js--chained-expression-p))
((js--ctrl-statement-indentation))
((js--multi-line-declaration-indentation))
((nth 1 parse-status)
......
// Normal chaining.
let x = svg.mumble()
.zzz;
// Chaining with an intervening line comment.
let x = svg.mumble() // line comment
.zzz;
// Chaining with multiple dots.
let x = svg.selectAll().something()
.zzz;
// Nested chaining.
let x = svg.selectAll(d3.svg.something()
.zzz);
// Nothing to chain to.
let x = svg()
.zzz;
// Nothing to chain to.
let x = svg().mumble.x() + 73
.zzz;
// Local Variables:
// indent-tabs-mode: nil
// js-chain-indent: t
// js-indent-level: 2
// End:
......@@ -124,6 +124,10 @@ if (x > 72 &&
do_something();
}
// Test that chaining doesn't happen when js-chain-indent is nil.
let x = svg.mumble()
.zzz;
// Local Variables:
// indent-tabs-mode: nil
// js-indent-level: 2
......
Markdown is supported
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment