Class: ContentUrls::CssParser

Inherits:
Object
  • Object
show all
Defined in:
lib/content_urls/parsers/css_parser.rb

Overview

CssParser finds and rewrites URLs in CSS content.

Implementation note:

This methods in this class identify URLs by using regular expressions based on the W3C CSS 2.1 Specification (www.w3.org/TR/CSS21/syndata.html).

Class Method Summary collapse

Class Method Details

.rewrite_each_url(content, &block) ⇒ Object

Rewrites each URL in the CSS content by calling the supplied block with each URL.

Examples:

Rewrite URLs in CSS code

css = 'body { background: url(/images/rainbows.jpg) }'
css = ContentUrls::CssParser.rewrite_each_url(css) {|url| url.sub(/rainbows.jpg/, 'unicorns.jpg')}
puts "Rewritten: #{css}"
# => "Rewritten: body { background: url(/images/unicorns.jpg) }"

Parameters:

  • content (String) —

    the CSS content.



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# File 'lib/content_urls/parsers/css_parser.rb', line 40

def self.rewrite_each_url(content, &block)
  urls = {}
  parser = ::CssParser::Parser.new
  parser.load_string!(content)
  parser.each_selector do |selector|
    parser[selector].each do |element|
      remaining = element
      while !remaining.empty?
        if match = @@regex_uri.match(remaining)
          urls[match[:url]] = match[:uri]
          remaining = match.post_match
        else
          remaining = ''
        end
      end
    end
  end
  rewritten_content = [{:content => content, :is_rewritten => false}]
  urls.each do |property_value, url|
    rewritten_url = yield url
    if rewritten_url != url
      rewritten_property_value = property_value.dup
      rewritten_property_value[url] = rewritten_url
      i = 0
      while i < rewritten_content.count
        if !rewritten_content[i][:is_rewritten]
          if match = /#{Regexp.escape(property_value)}/.match(rewritten_content[i][:content])
            if match.pre_match.length > 0
              rewritten_content.insert(i, {:content => match.pre_match, :is_rewritten => false})
              i += 1
            end
            rewritten_content[i] = {:content => rewritten_property_value, :is_rewritten => true}
            if match.post_match.length > 0
              rewritten_content.insert(i+1, {:content => match.post_match, :is_rewritten => false})
            end
          end
        end
        i += 1
      end
    end
  end
  rewritten_content.map { |c| c[:content]}.join
end

.urls(content) ⇒ Array

Returns the URLs found in the CSS content.

Examples:

Parse CSS code for URLs

css = 'body { background: url(/images/rainbows.jpg) }'
ContentUrls::CssParser.urls(css).each do |url|
  puts "Found URL: #{url}"
end
# => "Found URL: /images/rainbows.jpg"

Parameters:

  • content (String) —

    the CSS content.

Returns:

  • (Array) —

    the unique URLs found in the content.



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# File 'lib/content_urls/parsers/css_parser.rb', line 23

def self.urls(content)
  urls = []
  rewrite_each_url(content) { |url| urls << url; url }
  urls.uniq!
  urls
end