Enhance terpri to allow conditionally output a newline

* doc/lispref/streams.texi (Output Functions): Document new argument ENSURE to
terpri.

* doc/misc/cl.texi (Porting Common Lisp): Remove parse-integer.

* lisp/emacs-lisp/cl-extra.el (cl-fresh-line): New function.

* src/keymap.c (describe_vector_princ):
* src/keyboard.c (Fcommand_error_default_function): Adapt to change to
Fterpri.

* src/print.c (printchar_stdout_last): Declare.
(printchar): Record the last char written to stdout.
(Fterpri): Add optional argument ENSURE.

* test/automated/print-tests.el: New file.
(terpri): Tests for terpri.  (Bug#18652)

2 files changed, 11 insertions, 3 deletions

diff --git a/doc/lispref/ChangeLog b/doc/lispref/ChangeLog
index 510f9e983c3..4d4d0b529cc 100644
--- a/doc/lispref/ChangeLog
+++ b/doc/lispref/ChangeLog
@@ -1,3 +1,8 @@
+2014-10-08  Leo Liu  <sdl.web@gmail.com>
+
+        * streams.texi (Output Functions): Document new argument ENSURE to
+        terpri.  (Bug#18652)
+
 2014-10-04  Martin Rudalics  <rudalics@gmx.at>
 
         * display.texi (Scroll Bars): Add description of horizontal scroll
diff --git a/doc/lispref/streams.texi b/doc/lispref/streams.texi
index 1d549ae8916..c287b617713 100644
--- a/doc/lispref/streams.texi
+++ b/doc/lispref/streams.texi
@@ -615,10 +615,13 @@ spacing between calls.
 @end example
 @end defun
 
-@defun terpri &optional stream
+@defun terpri &optional stream ensure
 @cindex newline in print
-This function outputs a newline to @var{stream}.  The name stands
-for ``terminate print''.
+This function outputs a newline to @var{stream}.  The name stands for
+``terminate print''.  If @var{ensure} is non-nil no newline is printed
+if @var{stream} is already at the beginning of a line.  Note in this
+case @var{stream} can not be a function and an error is signalled if
+it is.  This function returns @code{t} if a newline is printed.
 @end defun
 
 @defun write-char character &optional stream