gistfile1.rb

require 'zlib'

dict = "hello"
str = "hello, hello!"

d = Zlib::Deflate.new
d.set_dictionary(dict)
comp_str = d.deflate(str)
comp_str << d.finish

i = Zlib::Inflate.new(Zlib::MAX_WBITS + 32)
i.set_dictionary(dict)
i << comp_str
uncomp_comp_str = i.finish

p uncomp_comp_str, str == uncomp_comp_str

gistfile2.rb

require 'zlib'

dict = "hello"
str = "hello, hello!"

d = Zlib::Deflate.new
d.set_dictionary(dict)
comp_str = d.deflate(str)
comp_str << d.finish

i = Zlib::Inflate.new(Zlib::MAX_WBITS + 32)

begin
  i.inflate(comp_str)
  rescue Zlib::NeedDict
end

i.set_dictionary(dict)
i << ""
uncomp_comp_str = i.finish

p uncomp_comp_str, str == uncomp_comp_str

gistfile3.rb

require 'zlib'

dict = "hello"
str = "hello, hello!"

d = Zlib::Deflate.new
d.set_dictionary(dict)
comp_str = d.deflate(str)
comp_str << d.finish

i = Zlib::Inflate.new(Zlib::MAX_WBITS + 32)

begin
  i << comp_str.slice!(0, 9)
  rescue Zlib::NeedDict
end

i.set_dictionary(dict)
i << comp_str
uncomp_comp_str = i.finish

p uncomp_comp_str, str == uncomp_comp_str