How to have c-offset style correctly detect a Java constructor and change indentation?

Question

Currently my team (non-Emacs users) indent java like so:

public DiskThresholdDecider(Settings settings,
                            NodeSettingsService nodeSettingsService,
                            ClusterInfoService infoService,
                            Client client) {
    String lowWatermark = settings.get(CLUSTER_ROUTING_ALLOCATION_LOW_DISK_WATERMARK,
            "85%");

There are two different indentation settings for the same c-style offset, for example (| denotes the cursor):

public DiskThresholdDecider(Settings settings,
                            |NodeSettingsService nodeSettingsService,
                            ClusterInfoService infoService,
                            Client client) {

C-c C-s (c-show-syntactic-information) returns (arglist-cont-nonempty ... ...)

Just a couple of lines down, on the method invocation, C-c C-s also returns (arglist-cont-nonempty ... ...) here:

    String lowWatermark = settings.get(CLUSTER_ROUTING_ALLOCATION_LOW_DISK_WATERMARK,
            |"85%");

In my configuration, I have this set up as:

(defconst intellij-java-style
  '((c-basic-offset . 4)
    (c-comment-only-line-offset . (0 . 0))
    (c-offsets-alist
     .
     ((inline-open . 0)
      (topmost-intro-cont    . +)
      (statement-block-intro . +)
      (knr-argdecl-intro     . +)
      (substatement-open     . +)
      (substatement-label    . +)
      (case-label            . +)
      (label                 . +)
      (statement-case-open   . +)
      (statement-cont        . ++)
      (arglist-intro         . 0)
      (arglist-cont-nonempty . ++) ;; <-- the actual setting
      (arglist-close         . --)
      (inexpr-class          . 0)
      (access-label          . 0)
      (inher-intro           . ++)
      (inher-cont            . ++)
      (brace-list-intro      . +)
      (func-decl-cont        . ++))))
  "Elasticsearch's Intellij Java Programming Style")

The problem is I need Emacs to treat class constructors as different indentation style than regular method invocations. This is so it will line up lines on the ( only for constructors.

Is there a function I can use to set for arglist-cont-nonempty that will indent this correctly or a way to do this?

Would it be sufficient to detect the arguments in a function declaration, as opposed to arguments of a constructor? — PythonNut
– PythonNut, Commented Oct 20, 2015 at 16:27
@PythonNut that would be perfect, in fact function declarations should indent the same way as constructor calls — Lee H
– Lee H, Commented Oct 20, 2015 at 17:44

PythonNut · Accepted Answer · 2015-10-20 18:50:17Z

4

+50

Try the following:

(defun my/point-in-defun-declaration-p ()
  (let ((bod (save-excursion (c-beginning-of-defun)
                             (point))))
    (<= bod
        (point)
        (save-excursion (goto-char bod)
                        (re-search-forward "{")
                        (point)))))

(defun my/arglist-cont-nonempty-indentation (arg)
  (unless (my/point-in-defun-declaration-p) '++))

(push '(arglist-cont-nonempty 
        my/arglist-cont-nonempty-indentation 
        c-lineup-gcc-asm-reg 
        c-lineup-arglist) 
      c-offsets-alist)

I tested it, and it appears to be working.

answered Oct 20, 2015 at 18:50

PythonNut

10.5k3 gold badges33 silver badges81 bronze badges

This is great! I have modified it slightly to handle all the edge cases Java indentation unfortunately has. Full version here: gist.github.com/dakrone/0b4888de1ca142641b28

Lee H
– Lee H

2015-10-21 03:09:00 +00:00
Commented Oct 21, 2015 at 3:09
@LeeH great to hear. Man, this is why I love LISP. :)

PythonNut
– PythonNut

2015-10-21 04:43:00 +00:00
Commented Oct 21, 2015 at 4:43

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