Class: FileReverseReader

Inherits:
Object
  • Object
show all
Defined in:
lib/file_reverse_reader.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(io, step = 1024 * 1024 * 1) ⇒ FileReverseReader

Returns a new instance of FileReverseReader.



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# File 'lib/file_reverse_reader.rb', line 4

def initialize(io, step = 1024 * 1024 * 1)
  @io = io
  @step = step
end

Instance Attribute Details

#io ⇒ Object (readonly)

Returns the value of attribute io.



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# File 'lib/file_reverse_reader.rb', line 2

def io
  @io
end

#step ⇒ Object (readonly)

Returns the value of attribute step.



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# File 'lib/file_reverse_reader.rb', line 2

def step
  @step
end

Instance Method Details

#binary_file? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/file_reverse_reader.rb', line 37

def binary_file?
  sample = io.read(1024) || ""
  sample2 = sample.force_encoding('ascii-8bit').encode('us-ascii', :undef => :replace, :invalid => :replace, :replace => "")
  sample != sample2 # maybe binary file
ensure
  io.rewind
end

#each_line(&block) ⇒ Object 



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# File 'lib/file_reverse_reader.rb', line 9

def each_line(&block)
  io.seek(0, IO::SEEK_END)
  buf = ""
  loop do
    if reach_start_of_file?
      last_pos = io.pos
      io.seek(0, IO::SEEK_SET)
      buf.insert(0, io.read(last_pos))
      split_each_line(buf, &block)
      break
    end

    io.seek(-1 * step, IO::SEEK_CUR)
    buf.insert(0, io.read(step))
    io.seek(-1 * step, IO::SEEK_CUR)
    next if buf[$/].nil?
    gap = buf.index($/)
    buf.gsub!(/\A.*?\n/, "")
    split_each_line(buf, &block)
    buf = ""
    io.seek(gap, IO::SEEK_CUR)
  end
end

#tail(limit = 10) ⇒ Object 



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# File 'lib/file_reverse_reader.rb', line 33

def tail(limit = 10)
  enum_for(:each_line).first(limit).reverse
end