sdk/platform-tools/systrace/catapult/common/py_vulcanize/third_party/rcssmin/README.rst

.. -*- coding: utf-8 -*-

=====================================
 rCSSmin - A CSS Minifier For Python
=====================================

TABLE OF CONTENTS
-----------------

1. Introduction
2. Copyright and License
3. System Requirements
4. Installation
5. Documentation
6. Bugs
7. Author Information


INTRODUCTION
------------

RCSSmin is a CSS minifier written in python.

The minifier is based on the semantics of the `YUI compressor`_\, which itself
is based on `the rule list by Isaac Schlueter`_\.

This module is a re-implementation aiming for speed instead of maximum
compression, so it can be used at runtime (rather than during a preprocessing
step). RCSSmin does syntactical compression only (removing spaces, comments
and possibly semicolons). It does not provide semantic compression (like
removing empty blocks, collapsing redundant properties etc). It does, however,
support various CSS hacks (by keeping them working as intended).

Here's a feature list:

- Strings are kept, except that escaped newlines are stripped
- Space/Comments before the very end or before various characters are
  stripped: ``:{});=>+],!`` (The colon (``:``) is a special case, a single
  space is kept if it's outside a ruleset.)
- Space/Comments at the very beginning or after various characters are
  stripped: ``{}(=:>+[,!``
- Optional space after unicode escapes is kept, resp. replaced by a simple
  space
- whitespaces inside ``url()`` definitions are stripped
- Comments starting with an exclamation mark (``!``) can be kept optionally.
- All other comments and/or whitespace characters are replaced by a single
  space.
- Multiple consecutive semicolons are reduced to one
- The last semicolon within a ruleset is stripped
- CSS Hacks supported:

  - IE7 hack (``>/**/``)
  - Mac-IE5 hack (``/*\*/.../**/``)
  - The boxmodelhack is supported naturally because it relies on valid CSS2
    strings
  - Between ``:first-line`` and the following comma or curly brace a space is
    inserted. (apparently it's needed for IE6)
  - Same for ``:first-letter``

rcssmin.c is a reimplementation of rcssmin.py in C and improves runtime up to
factor 100 or so (depending on the input). docs/BENCHMARKS in the source
distribution contains the details.

.. _YUI compressor: https://github.com/yui/yuicompressor/

.. _the rule list by Isaac Schlueter: https://github.com/isaacs/cssmin/


COPYRIGHT AND LICENSE
---------------------

Copyright 2011 - 2014
André Malo or his licensors, as applicable.

The whole package (except for the files in the bench/ directory)
is distributed under the Apache License Version 2.0. You'll find a copy in the
root directory of the distribution or online at:
<http://www.apache.org/licenses/LICENSE-2.0>.


SYSTEM REQUIREMENTS
-------------------

Both python 2 (>=2.4) and python 3 are supported.


INSTALLATION
------------

Using pip
~~~~~~~~~
 
$ pip install rcssmin
 

Using distutils
~~~~~~~~~~~~~~~
 
$ python setup.py install
 
The following extra options to the install command may be of interest:
 
   --without-c-extensions  Don't install C extensions
   --without-docs          Do not install documentation files
 

Drop-in
~~~~~~~
 
rCSSmin effectively consists of two files: rcssmin.py and rcssmin.c, the
latter being entirely optional. So, for simple integration you can just
copy rcssmin.py into your project and use it.


DOCUMENTATION
-------------

A generated API documentation is available in the docs/apidoc/ directory.
But you can just look into the module. It provides a simple function,
called cssmin which takes the CSS as a string and returns the minified
CSS as a string.

The module additionally provides a "streamy" interface:

$ python -mrcssmin <css >minified

It takes two options:

  -b  Keep bang-comments (Comments starting with an exclamation mark)
  -p  Force using the python implementation (not the C implementation)

The latest documentation is also available online at
<http://opensource.perlig.de/rcssmin/>.


BUGS
----

No bugs, of course. ;-)
But if you've found one or have an idea how to improve rcssmin, feel free to
send a pull request on `github <https://github.com/ndparker/rcssmin>`_ or
send a mail to <rcssmin-bugs@perlig.de>.


AUTHOR INFORMATION
------------------

André "nd" Malo <nd@perlig.de>
GPG: 0x8103A37E


  If God intended people to be naked, they would be born that way.
                                                   -- Oscar Wilde