Inflate.jl

Julia implementation of zlib decompression
Author GunnarFarneback
Popularity
14 Stars
Updated Last
7 Months Ago
Started In
September 2018

Inflate.jl

Inflate provides a pure Julia implementation of zlib decompression functionality, with both in- memory and streaming interfaces. This covers decompression of the Deflate algorithm and the Zlib and Gzip wrapper formats, as specified in RFC 1950, RFC 1951, and RFC 1952.

The main reasons to choose Inflate over CodecZlib are:

  • 100% Julia code - great for Julia purists.
  • No binary dependencies.
  • Actually no dependencies at all.
  • Can read gzip headers.

You should choose CodecZlib over Inflate if the points above are not compelling or one or more of the following applies to you:

  • Need to compress, not only decompress.
  • Want higher speed.
  • Want a full-featured streaming interface.
  • Want a battle-proven library.

In-Memory Decompression

In-memory decompression is done by the following functions:

function decompresses
inflate(data::Vector{UInt8}) raw Deflate data
inflate_zlib(data::Vector{UInt8}) Zlib data
inflate_gzip(data::Vector{UInt8}) Gzip data

They all take a Vector{UInt8} with compressed data as input and return a Vector{UInt8} of decompressed data. Additionally

gzip_headers = Dict{String, Any}()
out = inflate_gzip(data, headers = gzip_headers)

fills in gzip_headers with the Gzip headers present in data.

Both inflate_zlib and inflate_gzip accept the keyword argument ignore_checksum, which if set to true skips consistency checking by means of Adler and CRC checksums respectively. This disables the computation of the checksums, saving time.

Finally, there is also a convenience function to read a compressed text file in gzip format

out = inflate_gzip(filename::String)

This returns the decompressed file as a string.

Streaming Decompression

Streaming decompression is done using the following types:

stream decompresses
InflateStream(stream::IO) raw Deflate stream
InflateZlibStream(stream::IO) Zlib stream
InflateGzipStream(stream::IO) Gzip stream

The stream types are subtypes of IO and decompression is done by reading from instances of the types.

Example:

f = open("compressed_file.gz", "r")
gz = InflateGzipStream(f)
for line in readlines(gz)
    println(line)
end
close(f)

The streaming interface is minimalistic. If you need a full-featured interface, the CodecZlib package is likely to be a better fit.

Reading of Gzip headers can be done from the streaming interface too.

gzip_headers = Dict{String, Any}()
gz = InflateGzipStream(stream, headers = gzip_headers)

The retrieved headers will be available immediately upon construction of the InflateGzipStream. It is not necessary to read any data first.

Likewise both InflateZlibStream and InflateGzipStream accept the keyword argument ignore_checksum in the same way as the non-streaming functions inflate_zlib and inflate_gzip.

Required Packages

No packages found.