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require 'zlib'
require 'stringio'
##
# Provides a unified callback interface to decompression libraries.
module EventMachine::HttpDecoders
class DecoderError < StandardError
end
class << self
def accepted_encodings
DECODERS.inject([]) { |r,d| r + d.encoding_names }
end
def decoder_for_encoding(encoding)
DECODERS.each { |d|
return d if d.encoding_names.include? encoding
}
nil
end
end
class Base
def self.encoding_names
name = to_s.split('::').last.downcase
[name]
end
##
# chunk_callback:: [Block] To handle a decompressed chunk
def initialize(&chunk_callback)
@chunk_callback = chunk_callback
end
def <<(compressed)
return unless compressed && compressed.size > 0
decompressed = decompress(compressed)
receive_decompressed decompressed
end
def finalize!
decompressed = finalize
receive_decompressed decompressed
end
private
def receive_decompressed(decompressed)
if decompressed && decompressed.size > 0
@chunk_callback.call(decompressed)
end
end
protected
##
# Must return a part of decompressed
def decompress(compressed)
nil
end
##
# May return last part
def finalize
nil
end
end
class Deflate < Base
def decompress(compressed)
begin
@zstream ||= Zlib::Inflate.new(nil)
@zstream.inflate(compressed)
rescue Zlib::Error
raise DecoderError
end
end
def finalize
return nil unless @zstream
begin
r = @zstream.inflate(nil)
@zstream.close
r
rescue Zlib::Error
raise DecoderError
end
end
end
##
# Oneshot decompressor, due to lack of a streaming Gzip reader
# implementation. We may steal code from Zliby to improve this.
#
# For now, do not put `gzip' or `compressed' in your accept-encoding
# header if you expect much data through the :on_response interface.
class GZip < Base
def self.encoding_names
%w(gzip compressed)
end
def decompress(compressed)
@buf ||= ''
@buf += compressed
nil
end
def finalize
begin
Zlib::GzipReader.new(StringIO.new(@buf.to_s)).read
rescue Zlib::Error
raise DecoderError
end
end
end
DECODERS = [Deflate, GZip]
end
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