Start work on config infrastructure for ssh kitten

kittens/ssh/options/utils.py

@@ -0,0 +1,30 @@
+#!/usr/bin/env python
+# License: GPLv3 Copyright: 2022, Kovid Goyal <kovid at kovidgoyal.net>
+
+from typing import Any, Dict, Optional
+
+
+def init_results_dict(ans: Dict[str, Any]) -> Dict[str, Any]:
+    ans['current_hostname'] = '*'
+    ans['current_host_dict'] = chd = {'hostname': '*'}
+    ans['per_host_dicts'] = {'*': chd}
+    return ans
+
+
+ignored_dict_keys = tuple(init_results_dict({}))
+
+
+def hostname(val: str, dict_with_parse_results: Optional[Dict[str, Any]] = None) -> str:
+    if dict_with_parse_results is not None:
+        ch = dict_with_parse_results['current_hostname']
+        if val != ch:
+            hd = dict_with_parse_results.copy()
+            for k in ignored_dict_keys:
+                del hd[k]
+            phd = dict_with_parse_results['per_host_dicts']
+            phd[ch] = hd
+            dict_with_parse_results.clear()
+            dict_with_parse_results['per_host_dicts'] = phd
+            dict_with_parse_results['current_hostname'] = val
+            dict_with_parse_results['current_host_dict'] = phd.setdefault(val, {'hostname': val})
+    return val