Add a utility function buffer-narrowed-p, and use it.

* lisp/subr.el (buffer-narrowed-p): New function.

* lisp/ses.el (ses-widen):
* lisp/simple.el (count-words--buffer-message):
* lisp/net/browse-url.el (browse-url-of-buffer): Use it

* lisp/simple.el (count-words-region): Don't signal an error if there
is a non-nil prefix arg and the mark is not set.

* doc/lispref/positions.texi (Narrowing): Document buffer-narrowed-p.

2 files changed, 19 insertions, 12 deletions

diff --git a/doc/lispref/ChangeLog b/doc/lispref/ChangeLog
index bd21100dd4c..179f81990a7 100644
--- a/doc/lispref/ChangeLog
+++ b/doc/lispref/ChangeLog
@@ -1,5 +1,7 @@
 2012-09-07  Chong Yidong  <cyd@gnu.org>
 
+        * positions.texi (Narrowing): Document buffer-narrowed-p.
+
         * markers.texi (Moving Markers): Add xref to Point (Bug#7151).
 
         * syntax.texi (Low-Level Parsing): Add xref to Parser State
diff --git a/doc/lispref/positions.texi b/doc/lispref/positions.texi
index a0c65319850..c4576e6456d 100644
--- a/doc/lispref/positions.texi
+++ b/doc/lispref/positions.texi
@@ -874,18 +874,18 @@ commands to a limited range of characters in a buffer.  The text that
 remains addressable is called the @dfn{accessible portion} of the
 buffer.
 
-  Narrowing is specified with two buffer positions which become the
-beginning and end of the accessible portion.  For most editing commands
-and most Emacs primitives, these positions replace the values of the
-beginning and end of the buffer.  While narrowing is in effect, no text
-outside the accessible portion is displayed, and point cannot move
-outside the accessible portion.
-
-  Values such as positions or line numbers, which usually count from the
-beginning of the buffer, do so despite narrowing, but the functions
-which use them refuse to operate on text that is inaccessible.
-
-  The commands for saving buffers are unaffected by narrowing; they save
+  Narrowing is specified with two buffer positions, which become the
+beginning and end of the accessible portion.  For most editing
+commands and primitives, these positions replace the values of the
+beginning and end of the buffer.  While narrowing is in effect, no
+text outside the accessible portion is displayed, and point cannot
+move outside the accessible portion.  Note that narrowing does not
+alter actual buffer positions (@pxref{Point}); it only determines
+which positions are considered the accessible portion of the buffer.
+Most functions refuse to operate on text that is outside the
+accessible portion.
+
+  Commands for saving buffers are unaffected by narrowing; they save
 the entire buffer regardless of any narrowing.
 
   If you need to display in a single buffer several very different
@@ -924,6 +924,11 @@ It is equivalent to the following expression:
 @end example
 @end deffn
 
+@defun buffer-narrowed-p
+This function returns non-@code{nil} if the buffer is narrowed, and
+@code{nil} otherwise.
+@end defun
+
 @defspec save-restriction body@dots{}
 This special form saves the current bounds of the accessible portion,
 evaluates the @var{body} forms, and finally restores the saved bounds,