Add each_line enumerator to IO class

lib/piperator/io.rb

@@ -49,6 +49,13 @@ def gets(separator = $INPUT_RECORD_SEPARATOR, _limit = nil)
       read_with { @buffer.gets(separator) }
     end
 
+    # Returns an enumerator of lines in the stream, without reading the entire stream into memory
+    #
+    # @return [Enumerator]
+    def each_line
+      Enumerator.new { |y| loop { y << gets&.gsub(/#{$INPUT_RECORD_SEPARATOR}$/, '') } }.lazy.take_while(&:itself).each
+    end  
+
     # Flush internal buffer until the last unread byte
     def flush
       if @buffer.pos == @buffer_read_pos

spec/piperator/io_spec.rb

@@ -81,6 +81,14 @@
     end
   end
 
+  describe '#each_line' do
+    subject { Piperator::IO.new(["foo\n", "bar\n", "baz\nbmp"].each) }
+
+    it 'return enumerated lines' do
+      expect(subject.each_line.to_a).to eq(["foo", "bar", "baz", "bmp"])
+    end
+  end
+
   describe '#flush' do
     subject { Piperator::IO.new(['a' * 16 * KILOBYTE].each) }
     let(:flush_threshold) { Piperator::IO::FLUSH_THRESHOLD }