Improve `forward-sexp' in *Help* buffers

* lisp/help-mode.el (help-mode-syntax-table): New variable (bug#39134).
(help-make-xrefs): Use it to make picking out symbols in curved
quotes work reliably.
(help-xref-on-pp): Ditto.

diff --git a/lisp/help-mode.el b/lisp/help-mode.el
index e2d8ee0f59167282fc4774db87823e886cacfd42..b53d00d0fb8ec1bb147b9c6622e43db804822a20 100644 (file)
--- a/lisp/help-mode.el
+++ b/lisp/help-mode.el
@@ -140,6 +140,15 @@ The format is (FUNCTION ARGS...).")
 (setq-default help-xref-stack nil help-xref-stack-item nil)
 (setq-default help-xref-forward-stack nil help-xref-forward-stack-item nil)
 
+(defvar help-mode-syntax-table
+  (let ((table (make-syntax-table emacs-lisp-mode-syntax-table)))
+    ;; treat single quotes as parens so that forward-sexp does not
+    ;; break when quoted string contains punctuation
+    (modify-syntax-entry ?‘ "(’  " table)
+    (modify-syntax-entry ?’ ")‘  " table)
+    table)
+  "Syntax table used in `help-mode'.")
+
 (defcustom help-mode-hook nil
   "Hook run by `help-mode'."
   :type 'hook
@@ -520,7 +529,7 @@ that."
         (let ((stab (syntax-table))
               (case-fold-search t)
               (inhibit-read-only t))
-          (set-syntax-table emacs-lisp-mode-syntax-table)
+          (set-syntax-table help-mode-syntax-table)
           ;; The following should probably be abstracted out.
           (unwind-protect
               (progn
@@ -673,7 +682,7 @@ See `help-make-xrefs'."
 (defun help-xref-on-pp (from to)
   "Add xrefs for symbols in `pp's output between FROM and TO."
   (if (> (- to from) 5000) nil
-    (with-syntax-table emacs-lisp-mode-syntax-table
+    (with-syntax-table help-mode-syntax-table
       (save-excursion
        (save-restriction
          (narrow-to-region from to)