class Compress::LZ4::Writer

• Compress::LZ4::Writer
• IO
• Reference
• Object

Overview

A write-only IO object to compress data in the LZ4 format.

Instances of this class wrap another IO object. When you write to this instance, it compresses the data and writes it to the underlying IO.

NOTE unless created with a block, #close must be invoked after all data has been written to a LZ4::Writer instance.

Example: compress a file

require "lz4"

File.write("file.txt", "abcd")

File.open("./file.txt", "r") do |input_file|
  File.open("./file.lz4", "w") do |output_file|
    Compress::LZ4::Writer.open(output_file) do |lz4|
      IO.copy(input_file, lz4)
    end
  end
end

Defined in:

Constructors

• .new(output : IO, options = CompressOptions.new, sync_close : Bool = false)
• .new(filename : String, options = CompressOptions.new)

  Creates a new writer to the given filename.

Class Method Summary

• .open(io : IO, options = CompressOptions.new, sync_close = false, &)

  Creates a new writer for the given io, yields it to the given block, and closes it at its end.

• .open(filename : String, options = CompressOptions.new, &)

  Creates a new writer to the given filename, yields it to the given block, and closes it at the end.

Instance Method Summary

• #close

  Ends the current LZ4 frame, the stream can still be written to, unless @sync_close

• #closed? : Bool

  Returns true if this IO is closed.

• #compressed_bytes : UInt64
• #compression_ratio : Float64

  Uncompressed bytes read / compressed bytes outputted so far in the stream

• #finalize
• #flush : Nil

  Flush LZ4 lib buffers even if a block isn't full

• #read(slice : Bytes)

  Reads at most slice.size bytes from this IO into slice.

• #sync_close=(sync_close : Bool)
• #sync_close? : Bool
• #uncompressed_bytes : UInt64
• #write(slice : Bytes) : Nil

  Writes the contents of slice into this IO.

Constructor Detail

Class Method Detail

Instance Method Detail

io = IO::Memory.new "hello"
slice = Bytes.new(4)
io.read(slice) # => 4
slice          # => Bytes[104, 101, 108, 108]
io.read(slice) # => 1
slice          # => Bytes[111, 101, 108, 108]
io.read(slice) # => 0

io = IO::Memory.new
slice = Bytes.new(4) { |i| ('a'.ord + i).to_u8 }
io.write(slice)
io.to_s # => "abcd"