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 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 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.