Implement transpose-words

3 files changed, 115 insertions, 1 deletions

diff --git a/lib/reline/key_actor/emacs.rb b/lib/reline/key_actor/emacs.rb
index 7354c9279e..134f424a2c 100644
--- a/lib/reline/key_actor/emacs.rb
+++ b/lib/reline/key_actor/emacs.rb
@@ -489,7 +489,7 @@ class Reline::KeyActor::Emacs < Reline::KeyActor::Base
     # 243 M-s
     :ed_unassigned,
     # 244 M-t
-    :ed_unassigned,
+    :ed_transpose_words,
     # 245 M-u
     :em_upper_case,
     # 246 M-v
diff --git a/lib/reline/line_editor.rb b/lib/reline/line_editor.rb
index 784b8dd7c4..b1769d958a 100644
--- a/lib/reline/line_editor.rb
+++ b/lib/reline/line_editor.rb
@@ -1406,6 +1406,19 @@ class Reline::LineEditor
     end
   end
 
+  private def ed_transpose_words(key)
+    left_word_start, middle_start, right_word_start, after_start = Reline::Unicode.ed_transpose_words(@line, @byte_pointer)
+    before = @line.byteslice(0, left_word_start)
+    left_word = @line.byteslice(left_word_start, middle_start - left_word_start)
+    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)
+    @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
+    @cursor = calculate_width(from_head_to_left_word)
+  end
+
   private def em_capitol_case(key)
     if @line.bytesize > @byte_pointer
       byte_size, _, new_str = Reline::Unicode.em_forward_word_with_capitalization(@line, @byte_pointer)
diff --git a/lib/reline/unicode.rb b/lib/reline/unicode.rb
index 5523d4fa31..4b30f044f3 100644
--- a/lib/reline/unicode.rb
+++ b/lib/reline/unicode.rb
@@ -188,6 +188,107 @@ class Reline::Unicode
     [byte_size, width]
   end
 
+  def self.ed_transpose_words(line, byte_pointer)
+    right_word_start = nil
+    size = get_next_mbchar_size(line, byte_pointer)
+    mbchar = line.byteslice(byte_pointer, size)
+    if size.zero?
+      # ' aaa bbb [cursor]'
+      byte_size = 0
+      while 0 < (byte_pointer + byte_size)
+        size = get_prev_mbchar_size(line, byte_pointer + byte_size)
+        mbchar = line.byteslice(byte_pointer + byte_size - size, size)
+        break if mbchar.encode(Encoding::UTF_8) =~ /\p{Word}/
+        byte_size -= size
+      end
+      while 0 < (byte_pointer + byte_size)
+        size = get_prev_mbchar_size(line, byte_pointer + byte_size)
+        mbchar = line.byteslice(byte_pointer + byte_size - size, size)
+        break if mbchar.encode(Encoding::UTF_8) =~ /\P{Word}/
+        byte_size -= size
+      end
+      right_word_start = byte_pointer + byte_size
+      byte_size = 0
+      while line.bytesize > (byte_pointer + byte_size)
+        size = get_next_mbchar_size(line, byte_pointer + byte_size)
+        mbchar = line.byteslice(byte_pointer + byte_size, size)
+        break if mbchar.encode(Encoding::UTF_8) =~ /\P{Word}/
+        byte_size += size
+      end
+      after_start = byte_pointer + byte_size
+    elsif mbchar.encode(Encoding::UTF_8) =~ /\p{Word}/
+      # ' aaa bb[cursor]b'
+      byte_size = 0
+      while 0 < (byte_pointer + byte_size)
+        size = get_prev_mbchar_size(line, byte_pointer + byte_size)
+        mbchar = line.byteslice(byte_pointer + byte_size - size, size)
+        break if mbchar.encode(Encoding::UTF_8) =~ /\P{Word}/
+        byte_size -= size
+      end
+      right_word_start = byte_pointer + byte_size
+      byte_size = 0
+      while line.bytesize > (byte_pointer + byte_size)
+        size = get_next_mbchar_size(line, byte_pointer + byte_size)
+        mbchar = line.byteslice(byte_pointer + byte_size, size)
+        break if mbchar.encode(Encoding::UTF_8) =~ /\P{Word}/
+        byte_size += size
+      end
+      after_start = byte_pointer + byte_size
+    else
+      byte_size = 0
+      while (line.bytesize - 1) > (byte_pointer + byte_size)
+        size = get_next_mbchar_size(line, byte_pointer + byte_size)
+        mbchar = line.byteslice(byte_pointer + byte_size, size)
+        break if mbchar.encode(Encoding::UTF_8) =~ /\p{Word}/
+        byte_size += size
+      end
+      if (byte_pointer + byte_size) == (line.bytesize - 1)
+        # ' aaa bbb [cursor] '
+        after_start = line.bytesize
+        while 0 < (byte_pointer + byte_size)
+          size = get_prev_mbchar_size(line, byte_pointer + byte_size)
+          mbchar = line.byteslice(byte_pointer + byte_size - size, size)
+          break if mbchar.encode(Encoding::UTF_8) =~ /\p{Word}/
+          byte_size -= size
+        end
+        while 0 < (byte_pointer + byte_size)
+          size = get_prev_mbchar_size(line, byte_pointer + byte_size)
+          mbchar = line.byteslice(byte_pointer + byte_size - size, size)
+          break if mbchar.encode(Encoding::UTF_8) =~ /\P{Word}/
+          byte_size -= size
+        end
+        right_word_start = byte_pointer + byte_size
+      else
+        # ' aaa [cursor] bbb '
+        right_word_start = byte_pointer + byte_size
+        while line.bytesize > (byte_pointer + byte_size)
+          size = get_next_mbchar_size(line, byte_pointer + byte_size)
+          mbchar = line.byteslice(byte_pointer + byte_size, size)
+          break if mbchar.encode(Encoding::UTF_8) =~ /\P{Word}/
+          byte_size += size
+        end
+        after_start = byte_pointer + byte_size
+      end
+    end
+    byte_size = right_word_start - byte_pointer
+    while 0 < (byte_pointer + byte_size)
+      size = get_prev_mbchar_size(line, byte_pointer + byte_size)
+      mbchar = line.byteslice(byte_pointer + byte_size - size, size)
+      break if mbchar.encode(Encoding::UTF_8) =~ /\p{Word}/
+      byte_size -= size
+    end
+    middle_start = byte_pointer + byte_size
+    byte_size = middle_start - byte_pointer
+    while 0 < (byte_pointer + byte_size)
+      size = get_prev_mbchar_size(line, byte_pointer + byte_size)
+      mbchar = line.byteslice(byte_pointer + byte_size - size, size)
+      break if mbchar.encode(Encoding::UTF_8) =~ /\P{Word}/
+      byte_size -= size
+    end
+    left_word_start = byte_pointer + byte_size
+    [left_word_start, middle_start, right_word_start, after_start]
+  end
+
   def self.vi_big_forward_word(line, byte_pointer)
     width = 0
     byte_size = 0