Re: nXML mode indentation

[N. Raghavendra]

At 2018-05-08T10:03:33+05:30, N. Raghavendra wrote:

> It looks like `nxml-compute-indent-from-previous-line' in nxml-mode.el
> is relevant, but I can't see how to modify or advise it.

I have made some progress, with this function.  I tried changing the
definition of `nxml-compute-indent-from-previous-line' as follows:

----------
diff --git a/lisp/nxml/nxml-mode.el b/lisp/nxml/nxml-mode.el
index e2b51bc..f2e185e 100644
--- a/lisp/nxml/nxml-mode.el
+++ b/lisp/nxml/nxml-mode.el
@@ -1377,10 +1377,17 @@ nxml-compute-indent-from-previous-line
                        (nxml-compute-indent-in-token bol))))
          (skip-chars-forward " \t\r\n"))
        (goto-char ref)
-       (+ (current-column)
-          (* nxml-child-indent
-             (+ (if (eq before-context 'start-tag) 1 0)
-                (if (eq after-context 'end-tag) -1 0))))))))
+        (message "bc=%s ac=%s" before-context after-context)
+        (cond ((and (eq before-context 'mixed)
+                    (eq after-context 'markup))
+               (+ (current-column) nxml-child-indent))
+              ((and (eq before-context 'markup)
+                    (eq after-context 'markup))
+               (current-column))
+             (t (+ (current-column)
+                   (* nxml-child-indent
+                      (+ (if (eq before-context 'start-tag) 1 0)
+                         (if (eq after-context 'end-tag) -1 0))))))))))

 (defun nxml-merge-indent-context-type (context)
   "Merge the indent context type CONTEXT with the token in `xmltok-type'.
----------

This almost gives me the indentation that I want, as in,

----------
<article>
  <section>
    <title>Kant lipsum</title>

    <para>Let us suppose that the noumena have nothing to do with
      necessity, since knowledge of the Categories is a posteriori.
      Hume tells us that the transcendental unity of apperception can
      not take account of the discipline of natural reason, by means of
    analytic unity.</para>
  </section>
</article>
----------

The only thing is that the last line in the para, the one starting with
"analytic", is not indented as I want it.  It should be indented to the
same column as the previous line, the one starting with "not".

I have put

(message "bc=%s ac=%s" before-context after-context)

to give me some idea of what is happening.  However, it does not produce
any message when I go to the troublesome last line of the para, and
press tab.

I'd appreciate if someone can help with this problem.  If it is better
off on emacs-devel, I'll move it there.

Thanks,
Raghu.

--
N. Raghavendra <raghu@hri.res.in>, http://www.retrotexts.net/
Harish-Chandra Research Institute, http://www.hri.res.in/