
Python module that pages output to the screen, reads keys and
console dimensions without executing external utils.

It was meant to be included in standard library
http://bugs.python.org/issue8408

| Author:  anatoly techtonik <techtonik@gmail.com>
| License: Public Domain (or MIT if a license is required)


Demo
----
::

  python -m pager <file>
  <command> | pager.py     (Windows only - see issue #7)
  pager.py < <file>        (Windows only)

  # run manual tests that are also a demo
  python -m pager --test


Status
------
3.3 (stable)
 - fix critical issue #6: 3.2 Broken on Linux, thanks
   Calvin Spealman (@ironfroggy) for reporting
 - reading content from stdin is Windows only feature
   for now (see issue #7)

3.2 (broken on Linux)
 - abort pagination if ESC or 'q' keys are pressed
 - prompt callback is now able to abort pagination by
   returning False
3.1 (broken on Linux)
 - supports piped input (tested on Windows)
3.0 (alpha) - API break in getch() function
 - reverted getch() behaviour changed in 2.0 - now
   getch() again returns single char
 - new constants with underline for getch() keys
 - new getchars() function that always returns list

2.2 (stable)
 - Linux: fix regression in version 2.1 - wrong name for
   _get_unix call produced NameError on this platform
   (issue #6, thanks Calvin Spealman for report)
2.1 (broken on Linux)
 - split getch() into _getch_unix() and _getch_windows()
   and detect correct flavor at import time (speedup)
2.0 (stable) - API break in getch() function
 - getch() now always returns list of characters
   (previously it could return single char). This is done
   to simplify the task of detecting keys from the
   returned result

1.4 (stable)
 - pager.py <file>
 - Linux: termios comments, docs and preparation for very
   likely API break in getch() function
1.3 (stable)
 - Windows: Python 3 requires getwch()
 - Windows: fix ENTER LEFT UP RIGHT DOWN ESC key codes
1.2 (stable)
 - add names for ENTER LEFT UP RIGHT DOWN ESC keys
 - manual tests for getch() (fixes bug #4)
 - dumpkey() helper function to get hex dump of a value
   returned by getch()
1.1 (stable)
 - Python 3 compatibility
 - echo() helper function for unbuffered output (in Py3
   output doesn't appear immediately on screen unless it
   ends with newline)
1.0 (stable)
 - getch() now returns list of chars for special keys
   (fixes bug #1 when special key skipped several pages)
 - page() callbacks receive obligatory pagenumber param
 - default page() callback now shows page number
0.2 (stable)
 - do not insert blank line between pages
0.1 (stable)
 - shows content page by page
 - allows to get console/terminal dimensions
 - works on Windows
 - works on Linux


API (output)
------------

..function:: **page(content, [pagecallback=prompt])**

  Output `content` iterable, calling `pagecallback` function after each
  page with page number as a parameter.  `pagecallback` function may
  return False to terminate pagination.

  Default `prompt()` callback shows  page number with 'Press any key to
  continue . . . ' prompt, waits for keypress and aborts if 'q', ESC or
  Ctrl-C are pressed.


..function:: **echo(msg)**

  Print msg to the screen without linefeed and flush the output.


..function:: **getwidth()**

  Return width of available window in characters.  If detection fails,
  return value of standard width 80.  Coordinate of the last character
  on a line is -1 from returned value. 


..function:: **getheight()**

  Return available window height in characters or 25 if detection fails.
  Coordinate of the last line is -1 from returned value. 


API (input)
------------

..function:: **getch()**

  Wait for keypress, return first char generated as a result.

  Arrows and special keys generate sequence of chars. Use `getchars`
  function to receive all chars generated or present in buffer.


..function:: **getchars()**

  Wait for keypress. Return list of chars generated as a result.
  More than one char in result list is returned when arrows and
  special keys are pressed. Returned sequences differ between
  platforms, so use constants defined in this module to guess
  correct keys.


..function:: **dumpkey(key)**

  Helper to convert result of `getch` (string) or `getchars` (list)
  to hex string.


Credits
-------

| Danny Yoo for getch()-like unbuffered character reading recipe
| http://code.activestate.com/recipes/134892-getch-like-unbuffered/

| Calvin Spealman (@ironfroggy), issue #6

References
----------

| Excellent tutorials for Win32 Console by Adrian Worley
| http://www.adrianxw.dk/SoftwareSite/index.html
| Console Reference on MSDN
| http://msdn.microsoft.com/en-us/library/ms682087%28VS.85%29.aspx

| Public Domain Curses library maintained by William McBrine
| http://pdcurses.sourceforge.net/

| Ioctl (input/output control) introduction from Wikipedia
| http://en.wikipedia.org/wiki/Ioctl
| Linux Programmer's Manual - ioctls for terminals and serial lines
| http://www.kernel.org/doc/man-pages/online/pages/man4/tty_ioctl.4.html
