Archive::Zip::Codec::Store::Decompress is a readable, IO-like wrapper around a readable, IO-like object which provides a CRC32 checksum of the data read 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#decompressor method.
Creates a new instance of this class using io as a data source. io must be readable and provide a read method as an IO instance would or errors will be raised when performing read operations.
This class has extremely limited seek capabilities. It is possible to seek with an offset of 0 and a whence of IO::SEEK_CUR. As a result, the pos and tell methods also work as expected.
Due to certain optimizations within IO::Like#seek and if there is data in the read buffer, the seek method can be used to seek forward from the current stream position up to the end of the buffer. Unless it is known definitively how much data is in the buffer, it is best to avoid relying on this behavior.
If io also responds to rewind, then the rewind method of this class can be used to reset the whole stream back to the beginning. Using seek of this class to seek directly to offset 0 using IO::SEEK_SET for whence will also work in this case.
Any other seeking attempts, will raise Errno::EINVAL exceptions.
The fill_size attribute is set to 0 by default under the assumption that io is already buffered.
# File lib/archive/zip/codec/store.rb, line 166 def initialize(io) @io = io @crc32 = 0 @uncompressed_size = 0 # Assume that the delegate IO object is already buffered. self.fill_size = 0 end
Creates a new instance of this class with the given arguments 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.
# File lib/archive/zip/codec/store.rb, line 132 def self.open(io) unstore_io = new(io) return unstore_io unless block_given? begin yield(unstore_io) ensure unstore_io.close unless unstore_io.closed? end end
Closes this object so that further read operations will fail. If close_delegate is true, the delegate object used as a data source will also be closed using its close method.
# File lib/archive/zip/codec/store.rb, line 177 def close(close_delegate = true) super() @io.close if close_delegate nil end
Returns an instance of Archive::Zip::DataDescriptor with information regarding the data which has passed through this object from the delegate object. It is recommended to call the close method before calling this in order to ensure that no further read operations change the state of this object.
# File lib/archive/zip/codec/store.rb, line 188 def data_descriptor DataDescriptor.new( @crc32, @uncompressed_size, @uncompressed_size ) end
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