From 02880d1f4a9ebd1c0a807376fcb25ccd908334b4 Mon Sep 17 00:00:00 2001
From: aycabta <aycabta@gmail.com>
Date: Thu, 6 Jun 2019 04:57:52 +0900
Subject: [PATCH] Skip transpose-words if less than 2 word

---
 lib/reline/line_editor.rb           |  1 +
 test/reline/test_key_actor_emacs.rb | 76 +++++++++++++++++++++++++++++
 2 files changed, 77 insertions(+)

diff --git a/lib/reline/line_editor.rb b/lib/reline/line_editor.rb
index 568cea8bd4..c5f00c28dc 100644
--- a/lib/reline/line_editor.rb
+++ b/lib/reline/line_editor.rb
@@ -1418,6 +1418,7 @@ class Reline::LineEditor
     middle = @line.byteslice(middle_start, right_word_start - middle_start)
     right_word = @line.byteslice(right_word_start, after_start - right_word_start)
     after = @line.byteslice(after_start, @line.bytesize - after_start)
+    return if left_word.empty? or right_word.empty?
     @line = before + right_word + middle + left_word + after
     from_head_to_left_word = before + right_word + middle + left_word
     @byte_pointer = from_head_to_left_word.bytesize
diff --git a/test/reline/test_key_actor_emacs.rb b/test/reline/test_key_actor_emacs.rb
index 4194659631..04edf6b31f 100644
--- a/test/reline/test_key_actor_emacs.rb
+++ b/test/reline/test_key_actor_emacs.rb
@@ -903,6 +903,82 @@ class Reline::KeyActor::Emacs::Test < Reline::TestCase
     assert_cursor_max(18)
   end
 
+  def test_ed_transpose_words_with_one_word
+    input_keys('abc  ')
+    assert_line('abc  ')
+    assert_byte_pointer_size('abc  ')
+    assert_cursor(5)
+    assert_cursor_max(5)
+    input_keys("\M-t", false)
+    assert_line('abc  ')
+    assert_byte_pointer_size('abc  ')
+    assert_cursor(5)
+    assert_cursor_max(5)
+    input_keys("\C-b", false)
+    assert_line('abc  ')
+    assert_byte_pointer_size('abc ')
+    assert_cursor(4)
+    assert_cursor_max(5)
+    input_keys("\M-t", false)
+    assert_line('abc  ')
+    assert_byte_pointer_size('abc ')
+    assert_cursor(4)
+    assert_cursor_max(5)
+    input_keys("\C-b" * 2, false)
+    assert_line('abc  ')
+    assert_byte_pointer_size('ab')
+    assert_cursor(2)
+    assert_cursor_max(5)
+    input_keys("\M-t", false)
+    assert_line('abc  ')
+    assert_byte_pointer_size('ab')
+    assert_cursor(2)
+    assert_cursor_max(5)
+    input_keys("\M-t", false)
+    assert_line('abc  ')
+    assert_byte_pointer_size('ab')
+    assert_cursor(2)
+    assert_cursor_max(5)
+  end
+
+  def test_ed_transpose_words_with_one_word_for_mbchar
+    input_keys('あいう  ')
+    assert_line('あいう  ')
+    assert_byte_pointer_size('あいう  ')
+    assert_cursor(8)
+    assert_cursor_max(8)
+    input_keys("\M-t", false)
+    assert_line('あいう  ')
+    assert_byte_pointer_size('あいう  ')
+    assert_cursor(8)
+    assert_cursor_max(8)
+    input_keys("\C-b", false)
+    assert_line('あいう  ')
+    assert_byte_pointer_size('あいう ')
+    assert_cursor(7)
+    assert_cursor_max(8)
+    input_keys("\M-t", false)
+    assert_line('あいう  ')
+    assert_byte_pointer_size('あいう ')
+    assert_cursor(7)
+    assert_cursor_max(8)
+    input_keys("\C-b" * 2, false)
+    assert_line('あいう  ')
+    assert_byte_pointer_size('あい')
+    assert_cursor(4)
+    assert_cursor_max(8)
+    input_keys("\M-t", false)
+    assert_line('あいう  ')
+    assert_byte_pointer_size('あい')
+    assert_cursor(4)
+    assert_cursor_max(8)
+    input_keys("\M-t", false)
+    assert_line('あいう  ')
+    assert_byte_pointer_size('あい')
+    assert_cursor(4)
+    assert_cursor_max(8)
+  end
+
   def test_ed_digit
     input_keys('0123')
     assert_byte_pointer_size('0123')