implement swap-selection-start-stop function

The swap-selection-start-stop function goes to the other end of the highlighted text, the equivalent of `o' for vim visual mode.

Add binding to the swap-selection-start-stop function, `o' when in visual
mode.

Document swap-selection-start-stop, begin-selection, end-selection, kill-selection.

3 files changed, 14 insertions, 0 deletions

diff --git a/src/input.cpp b/src/input.cpp
index c3e26815..b4277724 100644
--- a/src/input.cpp
+++ b/src/input.cpp
@@ -132,6 +132,7 @@ static const wchar_t * const name_arr[] =
     L"suppress-autosuggestion",
     L"accept-autosuggestion",
     L"begin-selection",
+    L"swap-selection-start-stop",
     L"end-selection",
     L"kill-selection",
     L"forward-jump",
@@ -242,6 +243,7 @@ static const wchar_t code_arr[] =
     R_SUPPRESS_AUTOSUGGESTION,
     R_ACCEPT_AUTOSUGGESTION,
     R_BEGIN_SELECTION,
+    R_SWAP_SELECTION_START_STOP,
     R_END_SELECTION,
     R_KILL_SELECTION,
     R_FORWARD_JUMP,
diff --git a/src/input_common.h b/src/input_common.h
index e605d18b..8f4cdd52 100644
--- a/src/input_common.h
+++ b/src/input_common.h
@@ -68,6 +68,7 @@ enum
     R_SUPPRESS_AUTOSUGGESTION,
     R_ACCEPT_AUTOSUGGESTION,
     R_BEGIN_SELECTION,
+    R_SWAP_SELECTION_START_STOP,
     R_END_SELECTION,
     R_KILL_SELECTION,
     R_FORWARD_JUMP,
diff --git a/src/reader.cpp b/src/reader.cpp
index a7e8ec7e..50c8c93d 100644
--- a/src/reader.cpp
+++ b/src/reader.cpp
@@ -4026,6 +4026,17 @@ const wchar_t *reader_readline(int nchars)
                 break;
             }
 
+            case R_SWAP_SELECTION_START_STOP:
+            {
+                if (!data->sel_active) break;
+                size_t tmp = data->sel_begin_pos;
+                data->sel_begin_pos = data->command_line.position;
+                data->sel_start_pos = data->command_line.position;
+                editable_line_t *el = data->active_edit_line();
+                update_buff_pos(el, tmp);
+                break;
+            }
+
             case R_END_SELECTION:
             {
                 data->sel_active = false;