Chris@0: # =GZip Simple
Chris@0: #
Chris@0: # A simplified interface to the gzip library +zlib+ (from the Ruby Standard Library.)
Chris@0: #
Chris@0: # Author: murphy (mail to murphy rubychan de)
Chris@0: #
Chris@0: # Version: 0.2 (2005.may.28)
Chris@0: #
Chris@0: # ==Documentation
Chris@0: #
Chris@0: # See +GZip+ module and the +String+ extensions.
Chris@0: #
Chris@0: module GZip
Chris@0: 
Chris@0:   require 'zlib'
Chris@0: 
Chris@0:   # The default zipping level. 7 zips good and fast.
Chris@0:   DEFAULT_GZIP_LEVEL = 7
Chris@0: 
Chris@0:   # Unzips the given string +s+.
Chris@0:   #
Chris@0:   # Example:
Chris@0:   #   require 'gzip_simple'
Chris@0:   #   print GZip.gunzip(File.read('adresses.gz'))
Chris@0:   def GZip.gunzip s
Chris@0:     Zlib::Inflate.inflate s
Chris@0:   end
Chris@0: 
Chris@0:   # Zips the given string +s+.
Chris@0:   #
Chris@0:   # Example:
Chris@0:   #   require 'gzip_simple'
Chris@0:   #   File.open('adresses.gz', 'w') do |file
Chris@0:   #     file.write GZip.gzip('Mum: 0123 456 789', 9)
Chris@0:   #   end
Chris@0:   #
Chris@0:   # If you provide a +level+, you can control how strong
Chris@0:   # the string is compressed:
Chris@0:   # - 0: no compression, only convert to gzip format
Chris@0:   # - 1: compress fast
Chris@0:   # - 7: compress more, but still fast (default)
Chris@0:   # - 8: compress more, slower
Chris@0:   # - 9: compress best, very slow
Chris@0:   def GZip.gzip s, level = DEFAULT_GZIP_LEVEL
Chris@0:     Zlib::Deflate.new(level).deflate s, Zlib::FINISH
Chris@0:   end
Chris@0: end
Chris@0: 
Chris@0: 
Chris@0: # String extensions to use the GZip module.
Chris@0: #
Chris@0: # The methods gzip and gunzip provide an even more simple
Chris@0: # interface to the ZLib:
Chris@0: #
Chris@0: #   # create a big string
Chris@0: #   x = 'a' * 1000
Chris@0: #   
Chris@0: #   # zip it
Chris@0: #   x_gz = x.gzip
Chris@0: #   
Chris@0: #   # test the result
Chris@0: #   puts 'Zipped %d bytes to %d bytes.' % [x.size, x_gz.size]
Chris@0: #   #-> Zipped 1000 bytes to 19 bytes.
Chris@0: #   
Chris@0: #   # unzipping works
Chris@0: #   p x_gz.gunzip == x  #-> true
Chris@0: class String
Chris@0:   # Returns the string, unzipped.
Chris@0:   # See GZip.gunzip
Chris@0:   def gunzip
Chris@0:     GZip.gunzip self
Chris@0:   end
Chris@0:   # Replaces the string with its unzipped value.
Chris@0:   # See GZip.gunzip
Chris@0:   def gunzip!
Chris@0:     replace gunzip
Chris@0:   end
Chris@0: 
Chris@0:   # Returns the string, zipped.
Chris@0:   # +level+ is the gzip compression level, see GZip.gzip.
Chris@0:   def gzip level = GZip::DEFAULT_GZIP_LEVEL
Chris@0:     GZip.gzip self, level
Chris@0:   end
Chris@0:   # Replaces the string with its zipped value.
Chris@0:   # See GZip.gzip.
Chris@0:   def gzip!(*args)
Chris@0:     replace gzip(*args)
Chris@0:   end
Chris@0: end
Chris@0: 
Chris@0: if $0 == __FILE__
Chris@0:   eval DATA.read, nil, $0, __LINE__+4
Chris@0: end
Chris@0: 
Chris@0: __END__
Chris@0: #CODE
Chris@0: 
Chris@0: # Testing / Benchmark
Chris@0: x = 'a' * 1000
Chris@0: x_gz = x.gzip
Chris@0: puts 'Zipped %d bytes to %d bytes.' % [x.size, x_gz.size]  #-> Zipped 1000 bytes to 19 bytes.
Chris@0: p x_gz.gunzip == x  #-> true
Chris@0: 
Chris@0: require 'benchmark'
Chris@0: 
Chris@0: INFO = 'packed to %0.3f%%'  # :nodoc:
Chris@0: 
Chris@0: x = Array.new(100000) { rand(255).chr + 'aaaaaaaaa' + rand(255).chr }.join
Chris@0: Benchmark.bm(10) do |bm|
Chris@0:   for level in 0..9
Chris@0:     bm.report "zip #{level}" do
Chris@0:       $x = x.gzip level
Chris@0:     end
Chris@0:     puts INFO % [100.0 * $x.size / x.size]
Chris@0:   end
Chris@0:   bm.report 'zip' do
Chris@0:     $x = x.gzip
Chris@0:   end
Chris@0:   puts INFO % [100.0 * $x.size / x.size]
Chris@0:   bm.report 'unzip' do
Chris@0:     $x.gunzip
Chris@0:   end
Chris@0: end