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# =GZip Simple

#

# A simplified interface to the gzip library +zlib+ (from the Ruby Standard Library.)

#

# Author: murphy (mail to murphy rubychan de)

#

# Version: 0.2 (2005.may.28)

#

# ==Documentation

#

# See +GZip+ module and the +String+ extensions.

#

module GZip

  require 'zlib'

  # The default zipping level. 7 zips good and fast.

  DEFAULT_GZIP_LEVEL = 7

  # Unzips the given string +s+.

  #

  # Example:

  #   require 'gzip_simple'

  #   print GZip.gunzip(File.read('adresses.gz'))

  def GZip.gunzip s

    Zlib::Inflate.inflate s

  end

  # Zips the given string +s+.

  #

  # Example:

  #   require 'gzip_simple'

  #   File.open('adresses.gz', 'w') do |file

  #     file.write GZip.gzip('Mum: 0123 456 789', 9)

  #   end

  #

  # If you provide a +level+, you can control how strong

  # the string is compressed:

  # - 0: no compression, only convert to gzip format

  # - 1: compress fast

  # - 7: compress more, but still fast (default)

  # - 8: compress more, slower

  # - 9: compress best, very slow

  def GZip.gzip s, level = DEFAULT_GZIP_LEVEL

    Zlib::Deflate.new(level).deflate s, Zlib::FINISH

  end

end

# String extensions to use the GZip module.

#

# The methods gzip and gunzip provide an even more simple

# interface to the ZLib:

#

#   # create a big string

#   x = 'a' * 1000

#   

#   # zip it

#   x_gz = x.gzip

#   

#   # test the result

#   puts 'Zipped %d bytes to %d bytes.' % [x.size, x_gz.size]

#   #-> Zipped 1000 bytes to 19 bytes.

#   

#   # unzipping works

#   p x_gz.gunzip == x  #-> true

class String

  # Returns the string, unzipped.

  # See GZip.gunzip

  def gunzip

    GZip.gunzip self

  end

  # Replaces the string with its unzipped value.

  # See GZip.gunzip

  def gunzip!

    replace gunzip

  end

  # Returns the string, zipped.

  # +level+ is the gzip compression level, see GZip.gzip.

  def gzip level = GZip::DEFAULT_GZIP_LEVEL

    GZip.gzip self, level

  end

  # Replaces the string with its zipped value.

  # See GZip.gzip.

  def gzip!(*args)

    replace gzip(*args)

  end

end

if $0 == __FILE__

  eval DATA.read, nil, $0, __LINE__+4

end

__END__

#CODE

# Testing / Benchmark

x = 'a' * 1000

x_gz = x.gzip

puts 'Zipped %d bytes to %d bytes.' % [x.size, x_gz.size]  #-> Zipped 1000 bytes to 19 bytes.

p x_gz.gunzip == x  #-> true

require 'benchmark'

INFO = 'packed to %0.3f%%'  # :nodoc:

x = Array.new(100000) { rand(255).chr + 'aaaaaaaaa' + rand(255).chr }.join

Benchmark.bm(10) do |bm|

  for level in 0..9

    bm.report "zip #{level}" do

      $x = x.gzip level

    end

    puts INFO % [100.0 * $x.size / x.size]

  end

  bm.report 'zip' do

    $x = x.gzip

  end

  puts INFO % [100.0 * $x.size / x.size]

  bm.report 'unzip' do

    $x.gunzip

  end

end