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228 lines
7.3 KiB
228 lines
7.3 KiB
.. image:: https://img.shields.io/travis/jquast/wcwidth.svg
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:target: https://travis-ci.org/jquast/wcwidth
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:alt: Travis Continous Integration
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.. image:: https://img.shields.io/coveralls/jquast/wcwidth.svg
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:target: https://coveralls.io/r/jquast/wcwidth
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:alt: Coveralls Code Coverage
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.. image:: https://img.shields.io/pypi/v/wcwidth.svg
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:target: https://pypi.python.org/pypi/wcwidth/
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:alt: Latest Version
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.. image:: https://img.shields.io/github/license/jquast/wcwidth.svg
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:target: https://pypi.python.org/pypi/wcwidth/
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:alt: License
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.. image:: https://img.shields.io/pypi/wheel/wcwidth.svg
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:alt: Wheel Status
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.. image:: https://img.shields.io/pypi/dm/wcwidth.svg
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:target: https://pypi.python.org/pypi/wcwidth/
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:alt: Downloads
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============
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Introduction
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============
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This Library is mainly for those implementing a Terminal Emulator, or programs
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that carefully produce output to be interpreted by one.
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**Problem Statement**: When printed to the screen, the length of the string is
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usually equal to the number of cells it occupies. However, there are
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categories of characters that occupy 2 cells (full-wide), and others that
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occupy 0.
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**Solution**: POSIX.1-2001 and POSIX.1-2008 conforming systems provide
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`wcwidth(3)`_ and `wcswidth(3)`_ C functions of which this python module's
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functions precisely copy. *These functions return the number of cells a
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unicode string is expected to occupy.*
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This library aims to be forward-looking, portable, and most correct. The most
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current release of this API is based on the Unicode Standard release files:
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``DerivedGeneralCategory-9.0.0.txt``
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*Date: 2016-06-01, 10:34:26 GMT*
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© 2016 Unicode®, Inc.
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``EastAsianWidth-9.0.0.txt``
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*Date: 2016-05-27, 17:00:00 GMT [KW, LI]*
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© 2016 Unicode®, Inc.
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Installation
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------------
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The stable version of this package is maintained on pypi, install using pip::
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pip install wcwidth
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Example
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-------
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To Display ``u'コンニチハ'`` right-adjusted on screen of 80 columns::
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>>> from wcwidth import wcswidth
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>>> text = u'コンニチハ'
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>>> text_len = wcswidth(text)
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>>> print(u' ' * (80 - text_len) + text)
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wcwidth, wcswidth
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-----------------
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Use function ``wcwidth()`` to determine the length of a *single unicode
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character*, and ``wcswidth()`` to determine the length of a several, or a
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*string of unicode characters*.
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Briefly, return values of function ``wcwidth()`` are:
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``-1``
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Indeterminate (not printable).
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``0``
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Does not advance the cursor, such as NULL or Combining.
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``2``
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Characters of category East Asian Wide (W) or East Asian
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Full-width (F) which are displayed using two terminal cells.
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``1``
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All others.
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Function ``wcswidth()`` simply returns the sum of all values for each character
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along a string, or ``-1`` when it occurs anywhere along a string.
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More documentation is available using pydoc::
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$ pydoc wcwidth
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=======
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Caveats
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=======
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This library attempts to determine the printable width by an unknown targeted
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terminal emulator. It does not provide any ability to discern what the target
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emulator software, version, of level of support is. Results may vary!
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A `crude method
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<http://blessed.readthedocs.org/en/latest/examples.html#detect-multibyte-py>`_
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of determining the level of unicode support by the target emulator may be
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performed using the VT100 Query Cursor Position sequence.
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The libc version of `wcwidth(3)`_ is often several unicode releases behind,
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and therefor several levels of support lower than this python library. You
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may determine an exacting list of these discrepancies using the project
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file `wcwidth-libc-comparator.py
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<https://github.com/jquast/wcwidth/tree/master/bin/wcwidth-libc-comparator.py>`_.
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==========
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Developing
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==========
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Install wcwidth in editable mode::
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pip install -e.
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Install developer requirements::
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pip install -r requirements-develop.txt
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Execute unit tests using tox::
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tox
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Updating Tables
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---------------
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The command ``python setup.py update`` will fetch the following resources:
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- http://www.unicode.org/Public/UNIDATA/EastAsianWidth.txt
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- http://www.unicode.org/Public/UNIDATA/extracted/DerivedGeneralCategory.txt
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And generates the table files:
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- `wcwidth/table_wide.py <https://github.com/jquast/wcwidth/tree/master/wcwidth/table_wide.py>`_
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- `wcwidth/table_zero.py <https://github.com/jquast/wcwidth/tree/master/wcwidth/table_zero.py>`_
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Uses
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----
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This library is used in:
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- `jquast/blessed`_, a simplified wrapper around curses.
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- `jonathanslenders/python-prompt-toolkit`_, a Library for building powerful
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interactive command lines in Python.
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Additional tools for displaying and testing wcwidth are found in the `bin/
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<https://github.com/jquast/wcwidth/tree/master/bin>`_ folder of this project's
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source code. They are not distributed.
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=======
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History
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=======
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0.1.7 *2016-07-01*
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* **Updated** tables to Unicode Specification 9.0.0. (`PR #18`_).
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0.1.6 *2016-01-08 Production/Stable*
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* ``LICENSE`` file now included with distribution.
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0.1.5 *2015-09-13 Alpha*
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* **Bugfix**:
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Resolution of "combining_ character width" issue, most especially
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those that previously returned -1 now often (correctly) return 0.
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resolved by `Philip Craig`_ via `PR #11`_.
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* **Deprecated**:
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The module path ``wcwidth.table_comb`` is no longer available,
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it has been superseded by module path ``wcwidth.table_zero``.
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0.1.4 *2014-11-20 Pre-Alpha*
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* **Feature**: ``wcswidth()`` now determines printable length
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for (most) combining_ characters. The developer's tool
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`bin/wcwidth-browser.py`_ is improved to display combining_
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characters when provided the ``--combining`` option
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(`Thomas Ballinger`_ and `Leta Montopoli`_ `PR #5`_).
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* **Feature**: added static analysis (prospector_) to testing
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framework.
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0.1.3 *2014-10-29 Pre-Alpha*
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* **Bugfix**: 2nd parameter of wcswidth was not honored.
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(`Thomas Ballinger`_, `PR #4`_).
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0.1.2 *2014-10-28 Pre-Alpha*
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* **Updated** tables to Unicode Specification 7.0.0.
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(`Thomas Ballinger`_, `PR #3`_).
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0.1.1 *2014-05-14 Pre-Alpha*
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* Initial release to pypi, Based on Unicode Specification 6.3.0
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This code was originally derived directly from C code of the same name,
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whose latest version is available at
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http://www.cl.cam.ac.uk/~mgk25/ucs/wcwidth.c::
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* Markus Kuhn -- 2007-05-26 (Unicode 5.0)
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*
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* Permission to use, copy, modify, and distribute this software
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* for any purpose and without fee is hereby granted. The author
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* disclaims all warranties with regard to this software.
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.. _`prospector`: https://github.com/landscapeio/prospector
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.. _`combining`: https://en.wikipedia.org/wiki/Combining_character
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.. _`bin/wcwidth-browser.py`: https://github.com/jquast/wcwidth/tree/master/bin/wcwidth-browser.py
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.. _`Thomas Ballinger`: https://github.com/thomasballinger
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.. _`Leta Montopoli`: https://github.com/lmontopo
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.. _`Philip Craig`: https://github.com/philipc
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.. _`PR #3`: https://github.com/jquast/wcwidth/pull/3
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.. _`PR #4`: https://github.com/jquast/wcwidth/pull/4
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.. _`PR #5`: https://github.com/jquast/wcwidth/pull/5
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.. _`PR #11`: https://github.com/jquast/wcwidth/pull/11
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.. _`PR #18`: https://github.com/jquast/wcwidth/pull/18
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.. _`jquast/blessed`: https://github.com/jquast/blessed
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.. _`jonathanslenders/python-prompt-toolkit`: https://github.com/jonathanslenders/python-prompt-toolkit
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.. _`wcwidth(3)`: http://man7.org/linux/man-pages/man3/wcwidth.3.html
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.. _`wcswidth(3)`: http://man7.org/linux/man-pages/man3/wcswidth.3.html
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