add explicit IRC-aware comparison keys

plugins/python/_zoitechat_names.py

@@ -0,0 +1,74 @@
+"""Explicit immutable IRC names; existing string-returning APIs are unchanged."""
+import _zoitechat as api
+
+__all__ = ['IRCName', 'irc_casefold']
+
+
+def irc_casefold(text, casemapping='rfc1459'):
+    """Fold ASCII IRC characters only; never apply Unicode lower()/casefold()."""
+    if casemapping not in ('ascii', 'strict-rfc1459', 'rfc1459'):
+        raise ValueError('unsupported IRC casemapping')
+    extra = {'[': '{', ']': '}', '\\': '|'} if casemapping != 'ascii' else {}
+    if casemapping == 'rfc1459':
+        extra['^'] = '~'
+    return ''.join(chr(ord(c) + 32) if 'A' <= c <= 'Z' else extra.get(c, c)
+                   for c in text)
+
+
+class IRCName:
+    """Equality/hash include connection identity and the captured casemapping."""
+    __slots__ = ('_text', '_casemapping', '_connection_id', '_key')
+
+    def __init__(self, text, context=None, casemapping=None, connection_id=None):
+        context = context or api.get_context()
+        if casemapping is None:
+            casemapping = context.get_info('casemapping')
+            if casemapping is None:
+                raise RuntimeError('host does not expose its comparison casemapping')
+        if connection_id is None:
+            previous = api.get_context()
+            if not context.set():
+                raise ValueError('context has closed')
+            try:
+                connection_id = api.get_prefs('id')
+            finally:
+                previous.set()
+        object.__setattr__(self, '_text', text)
+        object.__setattr__(self, '_casemapping', casemapping)
+        object.__setattr__(self, '_connection_id', connection_id)
+        object.__setattr__(self, '_key', (connection_id, casemapping,
+                                       irc_casefold(text, casemapping)))
+
+    def __setattr__(self, name, value):
+        raise AttributeError('IRCName is immutable')
+
+    @property
+    def text(self):
+        return self._text
+
+    @property
+    def casemapping(self):
+        return self._casemapping
+
+    @property
+    def connection_id(self):
+        return self._connection_id
+
+    def __str__(self):
+        return self._text
+
+    def __repr__(self):
+        return 'IRCName({!r}, casemapping={!r}, connection_id={!r})'.format(
+            self._text, self._casemapping, self._connection_id)
+
+    def __eq__(self, other):
+        if not isinstance(other, IRCName):
+            return NotImplemented
+        return self._key == other._key
+
+    def __ne__(self, other):
+        result = self.__eq__(other)
+        return NotImplemented if result is NotImplemented else not result
+
+    def __hash__(self):
+        return hash(self._key)