[ruby/reline] Fix split_by_width to retain color sequences

(ruby/reline#490)

* Fix split_by_width to retain color sequences

* Add OSC escape sequence testcase of Reline::Unicode.split_by_width

Author: tompng

lib/reline/unicode.rb

@@ -160,24 +160,29 @@ def self.split_by_width(str, max_width, encoding = str.encoding)
     width = 0
     rest = str.encode(Encoding::UTF_8)
     in_zero_width = false
+    seq = String.new(encoding: encoding)
     rest.scan(WIDTH_SCANNER) do |gc|
       case
       when gc[NON_PRINTING_START_INDEX]
         in_zero_width = true
+        lines.last << NON_PRINTING_START
       when gc[NON_PRINTING_END_INDEX]
         in_zero_width = false
+        lines.last << NON_PRINTING_END
       when gc[CSI_REGEXP_INDEX]
         lines.last << gc[CSI_REGEXP_INDEX]
+        seq << gc[CSI_REGEXP_INDEX]
       when gc[OSC_REGEXP_INDEX]
         lines.last << gc[OSC_REGEXP_INDEX]
+        seq << gc[OSC_REGEXP_INDEX]
       when gc[GRAPHEME_CLUSTER_INDEX]
         gc = gc[GRAPHEME_CLUSTER_INDEX]
         unless in_zero_width
           mbchar_width = get_mbchar_width(gc)
           if (width += mbchar_width) > max_width
             width = mbchar_width
             lines << nil
-            lines << String.new(encoding: encoding)
+            lines << seq.dup
             height += 1
           end
         end

test/reline/test_unicode.rb

@@ -18,6 +18,15 @@ def test_ambiguous_width
     assert_equal 2, Reline::Unicode.calculate_width('√', true)
   end
 
+  def test_split_by_width
+    assert_equal [['abc', nil, 'de'], 2], Reline::Unicode.split_by_width('abcde', 3)
+    assert_equal [['abc', nil, 'def', nil, ''], 3], Reline::Unicode.split_by_width('abcdef', 3)
+    assert_equal [['ab', nil, 'あd', nil, 'ef'], 3], Reline::Unicode.split_by_width('abあdef', 3)
+    assert_equal [["ab\1zero\2c", nil, 'def', nil, ''], 3], Reline::Unicode.split_by_width("ab\1zero\2cdef", 3)
+    assert_equal [["\e[31mabc", nil, "\e[31md\e[42mef", nil, "\e[31m\e[42mg"], 3], Reline::Unicode.split_by_width("\e[31mabcd\e[42mefg", 3)
+    assert_equal [["ab\e]0;1\ac", nil, "\e]0;1\ad"], 2], Reline::Unicode.split_by_width("ab\e]0;1\acd", 3)
+  end
+
   def test_take_range
     assert_equal 'cdef', Reline::Unicode.take_range('abcdefghi', 2, 4)
     assert_equal 'いう', Reline::Unicode.take_range('あいうえお', 2, 4)