Allow using @selection in the launch cmdline

docs/conf.py

@@ -249,7 +249,9 @@ def write_cli_docs(all_kitten_names):
         f.write(option_spec_as_rst(
             appname='launch', ospec=launch_options_spec, heading_char='_',
             message='''\
-Launch an arbitrary program in a new kitty window/tab
+Launch an arbitrary program in a new kitty window/tab. Note that
+if you specify a program-to-run you can use the special placeholder
+:code:`@selection` which will be replaced by the current selection.
 '''
         ))
     with open('generated/cli-kitty.rst', 'w') as f:

kitty/boss.py

@@ -896,6 +896,9 @@ class Boss:
                 stdin = stdin.encode('utf-8')
         return env, stdin
 
+    def data_for_at(self, which, window=None, add_wrap_markers=False):
+        return data_for_at(window or self.active_window, which, add_wrap_markers=add_wrap_markers)
+
     def special_window_for_cmd(self, cmd, window=None, stdin=None, cwd_from=None, as_overlay=False):
         w = window or self.active_window
         env, stdin = self.process_stdin_source(w, stdin)

kitty/launch.py

@@ -164,7 +164,14 @@ def launch(boss, opts, args):
     if opts.copy_cmdline and active_child:
         cmd = active_child.foreground_cmdline
     if cmd:
-        kw['cmd'] = cmd
+        final_cmd = []
+        for x in cmd:
+            if x == '@selection' and active and not opts.copy_cmdline:
+                s = boss.data_for_at(active, x)
+                if s:
+                    x = s
+            final_cmd.append(x)
+        kw['cmd'] = final_cmd
     if opts.type == 'overlay' and active and not active.overlay_window_id:
         kw['overlay_for'] = active.id
     if opts.stdin_source: