Use `em_delete` in `key_delete` (#504)

* Test existing behavior

Typing Ctrl-D ends editing but typing <Del> does not.

Also renamed a test that is not testing ed_delete_next_char but
key_delete.

* Check if line empty first in em_delete

By distributivity of AND over OR, we can factor out this condition. This
will make the next commit simpler.

* Use em_delete in key_delete

When the editing mode is emacs, use `em_delete` in `key_delete`. We need
to add a condition though to `em_delete`, because it implements both
`delete-char` and `end-of-file`. We only want the `end-of-file` behavior
is the key is really Ctrl-D.

This matches the behavior of the <Del> key with readline, i.e. deleting
the next character if there is one, but not moving the cursor, while not
finishing the editing if there are no characters.

1 files changed, 26 insertions, 1 deletions

diff --git a/test/reline/test_key_actor_emacs.rb b/test/reline/test_key_actor_emacs.rb
index 40b26e5058..18a2448539 100644
--- a/test/reline/test_key_actor_emacs.rb
+++ b/test/reline/test_key_actor_emacs.rb
@@ -428,6 +428,12 @@ class Reline::KeyActor::Emacs::Test < Reline::TestCase
     assert_line("き\u3099")
   end
 
+  def test_em_delete_ends_editing
+    input_keys("\C-d") # quit from inputing
+    assert_line(nil)
+    assert(@line_editor.finished?)
+  end
+
   def test_ed_clear_screen
     refute(@line_editor.instance_variable_get(:@cleared))
     input_keys("\C-l", false)
@@ -449,7 +455,7 @@ class Reline::KeyActor::Emacs::Test < Reline::TestCase
     assert_line('abc')
   end
 
-  def test_ed_delete_next_char
+  def test_key_delete
     input_keys('abc')
     assert_cursor(3)
     assert_cursor_max(3)
@@ -459,6 +465,25 @@ class Reline::KeyActor::Emacs::Test < Reline::TestCase
     assert_line('abc')
   end
 
+  def test_key_delete_does_not_end_editing
+    @line_editor.input_key(Reline::Key.new(:key_delete, :key_delete, false))
+    assert_cursor(0)
+    assert_cursor_max(0)
+    assert_line('')
+    refute(@line_editor.finished?)
+  end
+
+  def test_key_delete_preserves_cursor
+    input_keys('abc')
+    input_keys("\C-b", false)
+    assert_cursor(2)
+    assert_cursor_max(3)
+    @line_editor.input_key(Reline::Key.new(:key_delete, :key_delete, false))
+    assert_cursor(2)
+    assert_cursor_max(2)
+    assert_line('ab')
+  end
+
   def test_em_next_word
     assert_byte_pointer_size('')
     assert_cursor(0)