Class: Squish::Bucket

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

Instance Method Summary collapse

Constructor Details

#initialize(name) ⇒ Bucket

Creates a new bucket with a given name.



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# File 'lib/squish.rb', line 62

def initialize(name)
  @name = name
end

Instance Method Details

#<<(document) ⇒ Object

Adds a document to the bucket. The supplied document must be a Hash. Suggested convention is to use a Hash such as this:

{
  :name => "Bob Aman",
  :email => "[email protected]",
  :body => <<-TEXT
    This is some example text from a hypothetical comment I left on
    someone's blog.
  TEXT
}

Supplying a String will convert the string to the form:

{
  :body => string
}

Automatically invalidates the previously calculated bucket data.



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# File 'lib/squish.rb', line 111

def <<(document)
  self.invalidate()
  document = {:body => document} if document.kind_of?(String)
  self.documents << document
  return self.documents
end

#compress(document) ⇒ Object

Returns the compression ratio for the given document with this bucket. The lower this number is, the better the fit.

Supplying a String will convert the string to the form:

{
  :body => string
}



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# File 'lib/squish.rb', line 127

def compress(document)
  document = {:body => document} if document.kind_of?(String)
  
  # Magically compress anything matched by the magnets to nothing.
  # This strongly attracts the document to this bucket.
  magnetized_document = document.dup
  for magnet in self.magnets
    regexp = nil
    if magnet.kind_of?(String)
      regexp = Regexp.new(Regexp.escape(magnet))
    elsif magnet.kind_of?(Regexp)
      regexp = magnet
    end
    if regexp != nil
      for key, value in magnetized_document
        value.gsub!(regexp, "")
      end
    end
  end
  
  document_bytes = Marshal.dump(
    Squish.filter_document(magnetized_document))
  document_compressed_binary = ""
  document_compressed_bytes = ""
  sorted_symbol_table =
    self.symbol_table.sort { |a, b| b[0].size <=> a[0].size }
  while document_bytes.size > 0
    for symbol, coding in sorted_symbol_table
      symbol_regexp = Regexp.new("^" + Regexp.escape(symbol))
      if document_bytes =~ symbol_regexp
        document_bytes.gsub!(symbol_regexp, "")
        document_compressed_binary << coding
        break
      end
    end
  end
  while document_compressed_binary != nil &&
      document_compressed_binary.size > 0
    document_compressed_bytes <<
      document_compressed_binary[0...8].to_i(2).chr
    document_compressed_binary = document_compressed_binary[8..-1]
  end
  return (document_compressed_bytes.size.to_f /
    Marshal.dump(document).size.to_f)
end

#documents ⇒ Object

Returns the list of documents contained within the bucket. Each document is simply a Hash object.



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# File 'lib/squish.rb', line 73

def documents
  if !defined?(@documents) || @documents.nil?
    @documents = []
  end
  return @documents
end

#invalidate ⇒ Object

Invalidates the bucket compression data. This method should be called any time the bucket’s list of documents changes. The << method calls this method automatically.



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

def invalidate
  @tree = nil
  @symbol_table = nil
end

#magnets ⇒ Object

Magnets are Strings or Regexps which can be attached to a bucket. They cause any incoming document that matches them to be very, very strongly attracted to the bucket that they are attached to. In essence, it makes the string that the magnet matches infinitely compressible by that bucket.



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# File 'lib/squish.rb', line 85

def magnets
  if !defined?(@magnets) || @magnets.nil?
    @magnets = []
  end
  return @magnets
end

#name ⇒ Object

Returns the name of the bucket.



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# File 'lib/squish.rb', line 67

def name
  return @name
end