Re: bug#31636: 27.0.50; lockfile syntax searchable from info manual

[Robert Pluim <rpluim@gmail.com>]

Latest version attached. I now limit the skip-syntax-backward to the
current line.

I have no idea how it was working correctly before, unless I somehow
managed to mess up the syntax table in my texinfo buffer (or more
likely I tested in a non-texinfo buffer). Testing appreciated.

((char-syntax (char-before)) at bol is '?>' in texinfo mode, which is
somewhat surprising, since it's '? ' in text mode)

Since the texinfo mode info documentation is part of the texinfo
package, Iʼll need to send them a patch as well.

2018-06-05  Robert Pluim  <rpluim@gmail.com>

	* lisp/textmodes/texinfo.el (texinfo-insert-dwim-@ref): New
	function. Insert appropriate type of reference based on
	surrounding text.
	(texinfo-mode-map): Add binding for texinfo-insert-dwim-@ref.

diff --git i/etc/NEWS w/etc/NEWS
index 01dcb441a7..a06bd442c2 100644
--- i/etc/NEWS
+++ w/etc/NEWS
@@ -171,6 +171,13 @@ interface that's more like functions like @code{search-forward}.
 \f
 * Changes in Specialized Modes and Packages in Emacs 27.1
 
+** Texinfo
+*** New function for inserting @pxref, @xref, or @ref commands.
+The function 'texinfo-insert-dwim-@ref', bound to 'C-c C-c r' by
+default, inserts one of three types of references based on the text
+surrounding point, namely @pxref after a parenthesis, @xref at the
+start of a sentence, else @ref.
+
 ** Browse-url
 *** The function 'browse-url-emacs' can now visit a URL in selected window.
 It now treats the optional 2nd argument to mean that the URL should be
diff --git i/lisp/textmodes/texinfo.el w/lisp/textmodes/texinfo.el
index ff723a4fb9..67333ddcf2 100644
--- i/lisp/textmodes/texinfo.el
+++ w/lisp/textmodes/texinfo.el
@@ -470,6 +470,7 @@ texinfo-mode-map
     (define-key map "\C-c\C-cu"    'texinfo-insert-@uref)
     (define-key map "\C-c\C-ct"    'texinfo-insert-@table)
     (define-key map "\C-c\C-cs"    'texinfo-insert-@samp)
+    (define-key map "\C-c\C-cr"    'texinfo-insert-dwim-@ref)
     (define-key map "\C-c\C-cq"    'texinfo-insert-@quotation)
     (define-key map "\C-c\C-co"    'texinfo-insert-@noindent)
     (define-key map "\C-c\C-cn"    'texinfo-insert-@node)
@@ -825,6 +826,36 @@ texinfo-insert-@quotation
   "Insert the string `@quotation' in a Texinfo buffer."
   \n "@quotation" \n _ \n)
 
+(define-skeleton texinfo-insert-dwim-@ref
+  "Insert appropriate `@pxref{...}', `@xref{}', or `@pef{}' command.
+Looks at text around point to decide what to insert; point after
+a parenthesis results in '@pxref{}', at the beginning of a
+sentence yields '@xref{}', any other location (including inside a
+word), will result in '@ref{}' at the nearest previous whitespace
+or beginning-of-line.
+A numeric argument says how many words the braces should
+surround.  The default is not to surround any existing words with
+the braces."
+  nil
+  (cond
+   ;; parenthesis
+   ((looking-back "\(")
+    "@pxref{")
+   ;; beginning of sentence
+   ((looking-back (sentence-end))
+    "@xref{")
+   ;; bol or eol
+   ((looking-at "^\\|$")
+    "@ref{")
+   ;; inside word
+   ((not (eq (char-syntax (char-after)) ? ))
+    (skip-syntax-backward "^ " (point-at-bol))
+    "@ref{")
+   ;; everything else
+   (t
+    "@ref{"))
+  _ "}")
+
 (define-skeleton texinfo-insert-@samp
   "Insert a `@samp{...}' command in a Texinfo buffer.
 A numeric argument says how many words the braces should surround.