Document TRIM in `split-string'.

* doc/lispref/strings.texi (Creating Strings): Document TRIM in
`split-string'.

2 files changed, 10 insertions, 1 deletions

diff --git a/doc/lispref/ChangeLog b/doc/lispref/ChangeLog
index aae5a1a6cc2..c598cf0f5aa 100644
--- a/doc/lispref/ChangeLog
+++ b/doc/lispref/ChangeLog
@@ -1,3 +1,7 @@
+2013-12-23  Xue Fuqiao  <xfq.free@gmail.com>
+
+        * strings.texi (Creating Strings): Document TRIM in `split-string'.
+
 2013-12-23  Chong Yidong  <cyd@gnu.org>
 
         * keymaps.texi (Controlling Active Maps): Renamed
diff --git a/doc/lispref/strings.texi b/doc/lispref/strings.texi
index 340115062f9..0fe319d97fb 100644
--- a/doc/lispref/strings.texi
+++ b/doc/lispref/strings.texi
@@ -268,7 +268,7 @@ string to be used as a shell command, see @ref{Shell Arguments,
 combine-and-quote-strings}.
 @end defun
 
-@defun split-string string &optional separators omit-nulls
+@defun split-string string &optional separators omit-nulls trim
 This function splits @var{string} into substrings based on the regular
 expression @var{separators} (@pxref{Regular Expressions}).  Each match
 for @var{separators} defines a splitting point; the substrings between
@@ -350,6 +350,11 @@ practice:
      @result{} ("o" "o" "o")
 @end example
 
+If the optional argument @var{trim} is non-@code{nil}, it should be a
+regular expression to match text to trim from the beginning and end of
+each substring.  If trimming makes the substring empty, it is treated
+as null.
+
 If you need to split a string into a list of individual command-line
 arguments suitable for @code{call-process} or @code{start-process},
 see @ref{Shell Arguments, split-string-and-unquote}.