Class: CSSFilter

Inherits:
Object
  • Object
show all
Defined in:
lib/cssfilter.rb

Overview

CSS Filter

The CSSFilter class will clean up a cascading style sheet. It can be used to remove whitespace and most importantly remove urls.

Issues

TODO: Allow urls to be specified per attribute type.

Copying

Copyright © 2007 Thomas Sawyer

Creative Commons Attribution-ShareAlike 3.0 License

See creativecommons.org/licenses/by-sa/3.0/

Defined Under Namespace

Classes: CLI, Tree

Constant Summary collapse

VERSION =

Library version.

"1.3.0"
DEFAULT =

CssFilter option defaults.

{
  'strip_comments' => true,
  'strip_urls' => true,
  'allowed_urls' => [],
  'allowed_hosts' => [],
  'allowed_scheme' => [],
  'strip_whitespace' => false,
  'strip_blanklines' => true,
  'rewrite' => false,
  'substitute_urls' => {}
}

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(options = nil) ⇒ CSSFilter

Returns a new instance of CSSFilter.



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# File 'lib/cssfilter.rb', line 76

def initialize(options=nil)
  if options
    h = DEFAULT.dup
    options.each do |k,v|
      h[k.to_s] = v
    end
    options = h
  else
    options = DEFAULT.dup
  end

  options.each{ |k,v| send("#{k}=",v) }
end

Instance Attribute Details

#allowed_hosts ⇒ Object

url hosts which will be allowed.



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# File 'lib/cssfilter.rb', line 41

def allowed_hosts
  @allowed_hosts
end

#allowed_scheme ⇒ Object Also known as: allowed_protocols

url schemes which will be allowed (http, ftp, mailto)



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# File 'lib/cssfilter.rb', line 34

def allowed_scheme
  @allowed_scheme
end

#allowed_urls ⇒ Object

urls which will be allowed. (NOT YET USED)



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# File 'lib/cssfilter.rb', line 44

def allowed_urls
  @allowed_urls
end

#rewrite ⇒ Object

Complete parse and rewrite of CSS document. This does a complete “cleaning” but note that is not yet a perfect parser.



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# File 'lib/cssfilter.rb', line 58

def rewrite
  @rewrite
end

#strip_blanklines ⇒ Object

remove blank lines.



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# File 'lib/cssfilter.rb', line 53

def strip_blanklines
  @strip_blanklines
end

#strip_comments ⇒ Object

should we remove comments? (true, false)



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# File 'lib/cssfilter.rb', line 28

def strip_comments
  @strip_comments
end

#strip_urls ⇒ Object

should we remove urls? (true, false)



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# File 'lib/cssfilter.rb', line 31

def strip_urls
  @strip_urls
end

#strip_whitespace ⇒ Object

remove blank lines.



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# File 'lib/cssfilter.rb', line 50

def strip_whitespace
  @strip_whitespace
end

#substitute_urls ⇒ Object

substitue urls (NOT YET USED)



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# File 'lib/cssfilter.rb', line 47

def substitute_urls
  @substitute_urls
end

Instance Method Details

#accept_host(host) ⇒ Object 



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# File 'lib/cssfilter.rb', line 92

def accept_host(host)
  @hosts << host
end

#clean_properties(atts) ⇒ Object

Takes a css entry and ensures it is valid (as best it can). It will fix trival mistakes, and raise an error when it is beyond repair.

TODO: So far this does absolutely nothing!



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# File 'lib/cssfilter.rb', line 176

def clean_properties(atts)
  atts
end

#clean_value(val) ⇒ Object 



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# File 'lib/cssfilter.rb', line 182

def clean_value(val)
  val = val.strip

  if urls
    uris = URI.extract(val)
    uris.each do |u|
      val.sub!(u.to_s, urls)
    end
  end

  return val
end

#filter(css) ⇒ Object 



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# File 'lib/cssfilter.rb', line 98

def filter(css)
  css = remove_comments(css)    if strip_comments
  css = remove_urls(css)        if strip_urls

  css = remove_nullvalues(css)

  css = remove_whitespace(css)  if strip_whitespace
  css = remove_blanklines(css)  if strip_blanklines

  css = parse(css).to_css       if rewrite
  css
end

#parse(css) ⇒ Object

Breaks a css document up into a hash. This can be used completely rewritting the css.

TODO: Not complete, does not work with “@xxx foo;” for example.



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# File 'lib/cssfilter.rb', line 156

def parse(css)
  tree = Tree.new
  entries = css.scan(/^(.*?)\{(.*?)\}/m)
  entries.each do |ref, props|
    tree[ref.strip] ||= {}
    props = clean_properties(props)
    props = props.scan(/(.*?)[:](.*?)([;]|\s*\Z)/)
    props.each do |(key,val)|
      tree[ref.strip][key.strip] = clean_value(val)
    end
  end
  return tree
end

#remove_blanklines(data) ⇒ Object 



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# File 'lib/cssfilter.rb', line 141

def remove_blanklines(data)
  data = data.gsub(/^\s*\n/,'')
end

#remove_comments(data) ⇒ Object 



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# File 'lib/cssfilter.rb', line 113

def remove_comments(data)
  data.gsub(/\/\*(.8?)\*\//,'')
end

#remove_nullvalues(data) ⇒ Object 



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# File 'lib/cssfilter.rb', line 147

def remove_nullvalues(data);
  data = data.gsub(/\w+[:](\s+)[;]/,'')
end

#remove_urls(data) ⇒ Object

TODO: allowed_urls



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# File 'lib/cssfilter.rb', line 119

def remove_urls(data)
  urls = data.scan(/url\((.*?)\)/).flatten
  uris = urls.collect{ |u| URI.extract(u) }.flatten
  uris.each do |u|
    uri = URI.parse(u)
    unless allowed_hosts.include?(uri.host) or
           allowed_scheme.include?(uri.scheme)
      data.sub!(u.to_s, '')
    end
  end
  data.gsub(/url\(\s*\)/, '')
end

#remove_whitespace(data) ⇒ Object 



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# File 'lib/cssfilter.rb', line 134

def remove_whitespace(data)
  data = data.gsub(/^\s*/,'')
  data = data.gsub(/\s*$/,'')
end