Metadata-Version: 2.0
Name: wcwidth
Version: 0.1.4
Summary: Measures number of Terminal column cells of wide-character codes
Home-page: https://github.com/jquast/wcwidth
Author: Jeff Quast
Author-email: contact@jeffquast.com
License: MIT
Keywords: terminal,emulator,wcwidth,wcswidth,cjk,combining,xterm,console
Platform: UNKNOWN
Classifier: Intended Audience :: Developers
Classifier: Natural Language :: English
Classifier: Development Status :: 2 - Pre-Alpha
Classifier: Environment :: Console
Classifier: License :: OSI Approved :: MIT License
Classifier: Operating System :: POSIX
Classifier: Programming Language :: Python :: 2.7
Classifier: Programming Language :: Python :: 3.3
Classifier: Programming Language :: Python :: 3.4
Classifier: Topic :: Software Development :: Libraries
Classifier: Topic :: Software Development :: Localization
Classifier: Topic :: Software Development :: Internationalization
Classifier: Topic :: Terminals

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    :alt: Latest Version

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    :alt: Downloads


============
Introduction
============

This API is mainly for Terminal Emulator implementors -- any python program
that attempts to determine the printable width of a string on a Terminal. It
is implemented in python (no C library calls) and has no 3rd-party dependencies.

It is certainly possible to use your Operating System's ``wcwidth(3)`` and
``wcswidth(3)`` calls if it is POSIX-conforming, but this would not be possible
on non-POSIX platforms, such as Windows, or for alternative Python
implementations, such as jython.  It is also commonly many releases older
than the most current Unicode Standard release files, which this project
aims to track.

The most current release of this API is based from Unicode Standard release
*7.0.0*, dated *2014-02-28, 23:15:00 GMT [KW, LI]* for table generated by
file ``EastAsianWidth-7.0.0.txt`` and *2014-02-07, 18:42:08 GMT [MD]* for
``DerivedCombiningClass-7.0.0.txt``.

Installation
------------

The stable version of this package is maintained on pypi, install using pip::

    pip install wcwidth

Problem
-------

You may have noticed some characters especially Chinese, Japanese, and
Korean (collectively known as the *CJK Unified Ideographs*) consume more
than 1 terminal cell. If you ask for the length of the string, ``u'コンニチハ'``
(Japanese: Hello), it is correctly determined to be a length of **5** using
the ``len()`` built-in.

However, if you were to print this to a Terminal Emulator, such as xterm,
urxvt, Terminal.app, PuTTY, or iTerm2, it would consume **10** *cells* (columns).
This causes problems for many of the text-alignment functions, such as ``rjust()``.
On an 80-wide terminal, the following would wrap along the margin, instead
of displaying it right-aligned as desired::

    >>> text = u'コンニチハ'
    >>> print(text.rjust(80))
                                                                                 コン
    ニチハ

Solution
--------

This API allows one to determine the printable length of these strings,
that the length of ``wcwidth(u'コ')`` is reported as ``2``, and
``wcswidth(u'コンニチハ')`` as ``10``.

This allows one to determine the printable effects of displaying *CJK*
characters on a terminal emulator.

wcwidth, wcswidth
-----------------
Use ``wcwidth`` to determine the length of a *single character*,
and ``wcswidth`` to determine the length of a *string of characters*.

To Display ``u'コンニチハ'`` right-adjusted on screen of 80 columns::

    >>> from wcwidth import wcswidth
    >>> text = u'コンニチハ'
    >>> print(u' ' * (80 - wcswidth(text)) + text)
                                                                           コンニチハ


Values
------

A general overview of return values:

   - ``-1``: indeterminate (see Todo_).

   - ``0``: do not advance the cursor, such as NULL.

   - ``2``: East_Asian_Width property values W and F (Wide and Full-width).

   - ``1``: all others.

``wcswidth()`` simply returns the sum of all values along a string, or
``-1`` if it has occurred for any value returned by ``wcwidth()``.  A more
exacting list of conditions and return values may be found in the docstring
for ``wcwidth()``.

Discrepacies
------------

There may be discrepancies with the determined printable width of of characters
by *wcwidth* and the results of any given terminal emulator -- most commonly,
emulators are using your Operating System's ``wcwidth(3)`` implementation which
is often based on tables much older than the most current Unicode Specification.
Python's determination of non-zero combining_ characters may also be based on an
older specification.

You may determine an exacting list of these discrepancies using files
`wcwidth-libc-comparator.py`_ and `wcwidth-combining-comparator.py`_

.. _`wcwidth-libc-comparator.py`: https://github.com/jquast/wcwidth/tree/master/bin/wcwidth-libc-comparator.py
.. _`wcwidth-combining-comparator.py`: https://github.com/jquast/wcwidth/tree/master/bin/wcwidth-combining-comparator.py


==========
Developing
==========

Execute the command ``python setup.py develop`` to prepare an environment
for running tests (``python setup.py test``), updating tables (
``python setup.py update``) or using any of the scripts in the ``bin/``
sub-folder.  These files are only made available in the source repository.


Updating Tables
---------------

The command ``python setup.py update`` will fetch the following resources:

    - http://www.unicode.org/Public/UNIDATA/EastAsianWidth.txt
    - http://www.unicode.org/Public/UNIDATA/extracted/DerivedCombiningClass.txt

And generate the table files `wcwidth/table_wide.py`_ and `wcwidth/table_comb.py`_.

.. _`wcwidth/table_wide.py`: https://github.com/jquast/wcwidth/tree/master/wcwidth/table_wide.py
.. _`wcwidth/table_comb.py`: https://github.com/jquast/wcwidth/tree/master/wcwidth/table_comb.py

wcwidth.c
---------

This code was originally derived directly from C code of the same name,
whose latest version is available at: `wcwidth.c`_ And is authored by
Markus Kuhn -- 2007-05-26 (Unicode 5.0)

.. _`wcwidth.c`: http://www.cl.cam.ac.uk/~mgk25/ucs/wcwidth.c


Examples
--------

This library is used in:

- `jquast/blessed`_, a simplified wrapper around curses.

- `jonathanslenders/python-prompt-toolkit`_, a Library for building powerful
  interactive command lines in Python.

Additional tools for displaying and testing wcwidth is found in the ``bin/``
folder of this project (github link: `wcwidth/bin`_). They are not distributed
as a script or part of the module.

.. _`jquast/blessed`: https://github.com/jquast/blessed
.. _`jonathanslenders/python-prompt-toolkit`: https://github.com/jonathanslenders/python-prompt-toolkit
.. _`wcwidth/bin`: https://github.com/jquast/wcwidth/tree/master/bin

Todo
----

Though some of the most common ("zero-width") `combining`_ characters
are understood by wcswidth, there are still many edge cases that need
to be covered, especially certain kinds of sequences such as those
containing Control-Sequence-Inducer (CSI).


License
-------

The original license is as follows::

    Permission to use, copy, modify, and distribute this software
    for any purpose and without fee is hereby granted. The author
    disclaims all warranties with regard to this software.

No specific licensing is specified, and Mr. Kuhn resides in the UK which allows
some protection from Copyrighting. As this derivative is based on US Soil,
an OSI-approved license that appears most-alike has been chosen, the MIT license::

    The MIT License (MIT)

    Copyright (c) 2014 <contact@jeffquast.com>

    Permission is hereby granted, free of charge, to any person obtaining a copy
    of this software and associated documentation files (the "Software"), to deal
    in the Software without restriction, including without limitation the rights
    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
    copies of the Software, and to permit persons to whom the Software is
    furnished to do so, subject to the following conditions:

    The above copyright notice and this permission notice shall be included in
    all copies or substantial portions of the Software.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
    THE SOFTWARE.

Changes
-------

0.1.4
  * **Feature**: ``wcswidth()`` now determines printable length
    for (most) combining characters.  The developer's tool
    `bin/wcwidth-browser.py`_ is improved to display combining_
    characters when provided the ``--combining`` option
    (`Thomas Ballinger`_ and `Leta Montopoli`_ `PR #5`_).
  * added static analysis (prospector_) to testing framework.

0.1.3
  * **Bugfix**: 2nd parameter of wcswidth was not honored.
    (`Thomas Ballinger`_, `PR #4`).

0.1.2
  * **Updated** tables to Unicode Specification 7.0.0.
    (`Thomas Ballinger`_, `PR #3`).

0.1.1
  * Initial release to pypi, Based on Unicode Specification 6.3.0

.. _`prospector`: https://github.com/landscapeio/prospector
.. _`combining`: https://en.wikipedia.org/wiki/Combining_character
.. _`bin/wcwidth-browser.py`: https://github.com/jquast/wcwidth/tree/master/bin/wcwidth-browser.py
.. _`Thomas Ballinger`: https://github.com/thomasballinger
.. _`Leta Montopoli`: https://github.com/lmontopo
.. _`PR #3`: https://github.com/jquast/wcwidth/pull/3
.. _`PR #4`: https://github.com/jquast/wcwidth/pull/4
.. _`PR #5`: https://github.com/jquast/wcwidth/pull/5


