Linefeed turns a chunked byte stream into individually yielded lines.

• https://github.com/inopinatus/linefeed
• https://inopinatus.github.io/linefeed/

When you're downstream of the read on a binary-mode chunked stream and want a push-style take on #each_line that doesn't burn too much memory.

gem install linefeed

Or add it to your Gemfile:

gem "linefeed"

Including Linefeed supplies two methods, #<< and #close. The idea is for external producers to drive processing by calls to these methods.

• #<< accepts an arbitrary-size chunk of incoming data and yields each LF-terminated line to a handler set by linefeed { |line| ... }. Lines yielded will be 8-bit ASCII strings and include the trailing LF.

• #close marks end-of-incoming-data; if any data persists in the buffer, this yields a final unterminated string to the same handler.

These method names are intentionally IO-ish so that you can mingle regular output files & IO streams with linefeed objects.

require "linefeed"

class Collector
  include Linefeed

  def initialize
    @lines = []
    linefeed { |line| @lines << line }
  end
end

collector = Collector.new
collector << "hello\nwor"
collector << "ld\n"
collector.close

# @lines => ["hello\n", "world\n"]

Write custom #<< and #close handlers by passing blocks to super blocks:

def <<(chunk)
  super(chunk) do |line|
    puts escape(line)
  end
end

def close
  super do |line|
    puts escape(line) + "\n"
  end
  puts " -- all done."
end

See Examples for more, like daisy-chaining, or updating a digest.

MIT license. Copyright (c) 2026 inopinatus

Visit https://github.com/inopinatus/linefeed to open a PR.