Add bind -x skeleton code

builtin/readline_osh.py

@@ -142,9 +142,7 @@ def Run(self, cmd_val):
                     readline.unbind_keyseq(arg.r)
 
                 if arg.x is not None:
-                    self.errfmt.Print_("warning: bind -x isn't implemented",
-                                       blame_loc=cmd_val.arg_locs[0])
-                    return 1
+                    readline.bind_shell_command(arg.x)
 
                 if arg.X:
                     readline.print_shell_cmd_map()

frontend/py_readline.py

@@ -137,6 +137,24 @@ def print_shell_cmd_map(self):
     def unbind_keyseq(self, keyseq):
         # type: (str) -> None
         line_input.unbind_keyseq(keyseq)
+
+    def bind_shell_command(self, cmdseq):
+        # type: (str) -> None
+        cmdseq_split = cmdseq.strip().split(":", 1)
+        if len(cmdseq_split) != 2:
+            raise ValueError("%s: missing colon separator" % cmdseq)
+
+        # Below checks prevent need to do so in C, but also ensure rl_generic_bind
+        # will not try to incorrectly xfree `cmd`/`data`, which doesn't belong to it
+        keyseq = cmdseq_split[0].rstrip()
+        if len(keyseq) <= 2:
+            raise ValueError("%s: empty binding key sequence" % keyseq)
+        if keyseq[0] != '"' or keyseq[-1] != '"':
+            raise ValueError("%s: missing double-quotes around the binding" % keyseq)
+        keyseq = keyseq[1:-1]
+
+        cmd = cmdseq_split[1]
+        line_input.bind_shell_command(keyseq, cmd)
 
 
 def MaybeGetReadline():

pyext/line_input.pyi

@@ -55,3 +55,4 @@ def print_shell_cmd_map() -> None: ...
 
 def unbind_keyseq(keyseq: str) -> None: ...
 
+def bind_shell_command(keyseq: str, cmd: str) -> None: ...