Class: Archive::Zip::Codec::Store::Compress

Inherits:
Object
  • Object
show all
Includes:
IO::Like
Defined in:
lib/archive/zip/codec/store.rb

Overview

Archive::Zip::Codec::Store::Compress is simply a writable, IO-like wrapper around a writable, IO-like object which provides a CRC32 checksum of the data written through it as well as the count of the total amount of data. A close method is also provided which can optionally close the delegate object. In addition a convenience method is provided for generating DataDescriptor objects based on the data which is passed through this object.

Instances of this class should only be accessed via the Archive::Zip::Codec::Store#compressor method.

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(io) ⇒ Compress

Creates a new instance of this class using io as a data sink. io must be writable and must provide a write method as IO does or errors will be raised when performing write operations.

The flush_size attribute is set to 0 by default under the assumption that io is already buffered.


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# File 'lib/archive/zip/codec/store.rb', line 47

def initialize(io)
  @io = io
  @crc32 = 0
  @uncompressed_size = 0
  # Assume that the delegate IO object is already buffered.
  self.flush_size = 0
end

Class Method Details

.open(io) ⇒ Object

Creates a new instance of this class with the given argument using #new and then passes the instance to the given block. The #close method is guaranteed to be called after the block completes.

Equivalent to #new if no block is given.


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# File 'lib/archive/zip/codec/store.rb', line 30

def self.open(io)
  store_io = new(io)
  return store_io unless block_given?

  begin
    yield(store_io)
  ensure
    store_io.close unless store_io.closed?
  end
end

Instance Method Details

#close(close_delegate = true) ⇒ Object

Closes this object so that further write operations will fail. If close_delegate is true, the delegate object used as a data sink will also be closed using its close method.


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# File 'lib/archive/zip/codec/store.rb', line 58

def close(close_delegate = true)
  super()
  @io.close if close_delegate
  nil
end

#data_descriptorObject

Returns an instance of Archive::Zip::DataDescriptor with information regarding the data which has passed through this object to the delegate object. The close or flush methods should be called before using this method in order to ensure that any possibly buffered data is flushed to the delegate object; otherwise, the contents of the data descriptor may be inaccurate.


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# File 'lib/archive/zip/codec/store.rb', line 70

def data_descriptor
  DataDescriptor.new(
    @crc32,
    @uncompressed_size,
    @uncompressed_size
  )
end