tui: Hint wrapped lines to terminals.

Previously, when neovim would wrap a line across multiple lines,
terminal emulators could not detect that the lines represent a single
wrapped line as opposed to several separate lines. As a result, many
terminals' selection/copying functionality would treat a wrapped line as
several newline-delimited lines.

Fix this by reenabling a "special trick" from Vim. When a line is
wrapped, write the last character of that line followed by the first
character of the next line to the terminal. This hints to the terminal
that the next line is a continuation of the current line.

Extends the raw_line event with a "wrap" parameter which controls when
to do wrap hinting.

1 files changed, 7 insertions, 32 deletions

diff --git a/src/nvim/ui.c b/src/nvim/ui.c
index 07aa032a50..e291111f82 100644
--- a/src/nvim/ui.c
+++ b/src/nvim/ui.c
@@ -80,7 +80,7 @@ static char uilog_last_event[1024] = { 0 };
 #endif
 
 // UI_CALL invokes a function on all registered UI instances. The functions can
-// have 0-5 arguments (configurable by SELECT_NTH).
+// have 0-10 arguments (configurable by SELECT_NTH).
 //
 // See http://stackoverflow.com/a/11172679 for how it works.
 #ifdef _MSC_VER
@@ -102,9 +102,9 @@ static char uilog_last_event[1024] = { 0 };
       } \
     } while (0)
 #endif
-#define CNT(...) SELECT_NTH(__VA_ARGS__, MORE, MORE, MORE, \
-                            MORE, MORE, MORE, MORE, MORE, ZERO, ignore)
-#define SELECT_NTH(a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, ...) a10
+#define CNT(...) SELECT_NTH(__VA_ARGS__, MORE, MORE, MORE, MORE, MORE, \
+                            MORE, MORE, MORE, MORE, ZERO, ignore)
+#define SELECT_NTH(a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, ...) a11
 #define UI_CALL_HELPER(c, ...) UI_CALL_HELPER2(c, __VA_ARGS__)
 // Resolves to UI_CALL_MORE or UI_CALL_ZERO.
 #define UI_CALL_HELPER2(c, ...) UI_CALL_##c(__VA_ARGS__)
@@ -315,10 +315,11 @@ void ui_set_ext_option(UI *ui, UIExtension ext, bool active)
   }
 }
 
-void ui_line(int row, int startcol, int endcol, int clearcol, int clearattr)
+void ui_line(int row, int startcol, int endcol, int clearcol, int clearattr,
+             bool wrap)
 {
   size_t off = LineOffset[row]+(size_t)startcol;
-  UI_CALL(raw_line, 1, row, startcol, endcol, clearcol, clearattr,
+  UI_CALL(raw_line, 1, row, startcol, endcol, clearcol, clearattr, wrap,
           (const schar_T *)ScreenLines+off, (const sattr_T *)ScreenAttrs+off);
   if (p_wd) {  // 'writedelay': flush & delay each time.
     int old_row = row, old_col = col;
@@ -341,32 +342,6 @@ void ui_cursor_goto(int new_row, int new_col)
   pending_cursor_update = true;
 }
 
-void ui_add_linewrap(int row)
-{
-  // TODO(bfredl): check that this actually still works
-  // and move to TUI module in that case.
-#if 0
-  // First make sure we are at the end of the screen line,
-  // then output the same character again to let the
-  // terminal know about the wrap.  If the terminal doesn't
-  // auto-wrap, we overwrite the character.
-  if (ui_current_col() != Columns) {
-    screen_char(LineOffset[row] + (unsigned)Columns - 1, row,
-                (int)(Columns - 1));
-  }
-
-  // When there is a multi-byte character, just output a
-  // space to keep it simple. */
-  if (ScreenLines[LineOffset[row] + (Columns - 1)][1] != 0) {
-    ui_putc(' ');
-  } else {
-    ui_puts(ScreenLines[LineOffset[row] + (Columns - 1)]);
-  }
-  // force a redraw of the first char on the next line
-  ScreenAttrs[LineOffset[row+1]] = (sattr_T)-1;
-#endif
-}
-
 void ui_mode_info_set(void)
 {
   pending_mode_info_update = true;