Extending custom grammar (#2436)

Extending custom grammar with actions

#492

## Checklist

- [x] I have added
[tests](https://www.cursorless.org/docs/contributing/test-case-recorder/)
- [/] I have updated the
[docs](https://github.com/cursorless-dev/cursorless/tree/main/docs) and
[cheatsheet](https://github.com/cursorless-dev/cursorless/tree/main/cursorless-talon/src/cheatsheet)
- [/] I have not broken the cheatsheet

---------

Co-authored-by: pre-commit-ci-lite[bot] <117423508+pre-commit-ci-lite[bot]@users.noreply.github.com>
Co-authored-by: Pokey Rule <[email protected]>

src/public_api.py

@@ -1,4 +1,6 @@
-from talon import Module
+from typing import Any, Optional
+
+from talon import Module, actions
 
 from .targets.target_types import (
     CursorlessDestination,
@@ -20,3 +22,21 @@ def cursorless_create_destination(
     ) -> CursorlessDestination:
         """Cursorless: Create destination from target"""
         return PrimitiveDestination(insertion_mode, target)
+
+
+@mod.action_class
+class CommandActions:
+    def cursorless_custom_command(
+        content: str,  # pyright: ignore [reportGeneralTypeIssues]
+        arg1: Optional[Any] = None,
+        arg2: Optional[Any] = None,
+        arg3: Optional[Any] = None,
+    ):
+        """Cursorless: Run custom parsed command"""
+        actions.user.private_cursorless_command_and_wait(
+            {
+                "name": "parsed",
+                "content": content,
+                "arguments": [arg for arg in [arg1, arg2, arg3] if arg is not None],
+            }
+        )