Fix creating CIMultiDict from MultiDict not making keys case-insentive

CHANGES/1112.bugfix.rst

@@ -0,0 +1 @@
+Fixed keys not becoming case-insensitive when :class:`multidict.CIMultiDict` is created by passing in a :class:`multidict.MultiDict` -- by :user:`bdraco`. 

multidict/_multidict_py.py

@@ -453,6 +453,8 @@ def _title(self, key: str) -> str:
 
 
 class _CIMixin:
+    _ci: bool = True
+
     def _key(self, key: str) -> str:
         if type(key) is istr:
             return key
@@ -474,6 +476,7 @@ def _title(self, key: str) -> str:
 
 class _Base(MultiMapping[_V]):
     _impl: _Impl[_V]
+    _ci: bool = False
 
     @abstractmethod
     def _key(self, key: str) -> str: ...
@@ -628,9 +631,13 @@ def _extend(
     ) -> None:
         if arg:
             if isinstance(arg, (MultiDict, MultiDictProxy)):
-                items = arg._impl._items
+                if self._ci != arg._ci:
+                    items = [(self._title(k), k, v) for _, k, v in arg._impl._items]
+                else:
+                    items = arg._impl._items
+                    if kwargs:
+                        items = items.copy()
                 if kwargs:
-                    items = items.copy()
                     for key, value in kwargs.items():
                         items.append((self._title(key), key, value))
             else:

multidict/_multilib/pair_list.h

@@ -1132,23 +1132,45 @@ static inline int
 pair_list_update_from_pair_list(pair_list_t *list, PyObject* used, pair_list_t *other)
 {
     Py_ssize_t pos;
+    Py_hash_t hash;
+    PyObject *identity = NULL;
+    bool recalc_identity = list->calc_ci_indentity != other->calc_ci_indentity;
 
     for (pos = 0; pos < other->size; pos++) {
         pair_t *pair = other->pairs + pos;
+        if (recalc_identity) {
+            identity = pair_list_calc_identity(list, pair->key);
+            if (identity == NULL) {
+                goto fail;
+            }
+            hash = PyObject_Hash(identity);
+            if (hash == -1) {
+                goto fail;
+            }
+        } else {
+            identity = pair->identity;
+            hash = pair->hash;
+        }
         if (used != NULL) {
             if (_pair_list_update(list, pair->key, pair->value, used,
-                                  pair->identity, pair->hash) < 0) {
+                                  identity, hash) < 0) {
                 goto fail;
             }
         } else {
-            if (_pair_list_add_with_hash(list, pair->identity, pair->key,
-                                         pair->value, pair->hash) < 0) {
+            if (_pair_list_add_with_hash(list, identity, pair->key,
+                                         pair->value, hash) < 0) {
                 goto fail;
             }
         }
+        if (recalc_identity) {
+            Py_CLEAR(identity);
+        }
     }
     return 0;
 fail:
+    if (recalc_identity) {
+        Py_CLEAR(identity);
+    }
     return -1;
 }
 

tests/test_multidict.py

@@ -19,6 +19,8 @@
     MultiMapping,
     MutableMultiMapping,
 )
+from multidict._multidict_py import CIMultiDict as PyCIMultiDict
+from multidict._multidict_py import MultiDict as PyMultiDict
 
 _T = TypeVar("_T")
 
@@ -1197,3 +1199,43 @@ def test_create_multidict_from_existing_multidict_new_pairs() -> None:
     new = MultiDict(original, h4="header4")
     assert "h4" in new
     assert "h4" not in original
+
+
+def test_convert_multidict_to_cimultidict_and_back() -> None:
+    """Test conversion from MultiDict to CIMultiDict."""
+    start_as_md = MultiDict([("KEY", "value1"), ("key2", "value2")])
+    assert start_as_md.get("KEY") == "value1"
+    assert start_as_md["KEY"] == "value1"
+    assert start_as_md.get("key2") == "value2"
+    assert start_as_md["key2"] == "value2"
+    start_as_cimd = CIMultiDict([("KEY", "value1"), ("key2", "value2")])
+    assert start_as_cimd.get("key") == "value1"
+    assert start_as_cimd["key"] == "value1"
+    assert start_as_cimd.get("key2") == "value2"
+    assert start_as_cimd["key2"] == "value2"
+    converted_to_ci = CIMultiDict(start_as_md)
+    assert converted_to_ci.get("key") == "value1"
+    assert converted_to_ci["key"] == "value1"
+    assert converted_to_ci.get("key2") == "value2"
+    assert converted_to_ci["key2"] == "value2"
+    converted_to_md = MultiDict(converted_to_ci)
+    assert converted_to_md.get("KEY") == "value1"
+    assert converted_to_md["KEY"] == "value1"
+    assert converted_to_md.get("key2") == "value2"
+    assert converted_to_md["key2"] == "value2"
+
+
+def test_pure_python_convert_multidict_to_cimultidict_eq() -> None:
+    """Test compare after conversion from MultiDict to CIMultiDict."""
+    original = PyMultiDict([("h1", "header1"), ("h2", "header2"), ("h3", "header3")])
+    assert PyCIMultiDict(original) == PyCIMultiDict(
+        [("H1", "header1"), ("H2", "header2"), ("H3", "header3")]
+    )
+
+
+def test_convert_multidict_to_cimultidict_eq() -> None:
+    """Test compare after conversion from MultiDict to CIMultiDict."""
+    original = MultiDict([("h1", "header1"), ("h2", "header2"), ("h3", "header3")])
+    assert CIMultiDict(original) == CIMultiDict(
+        [("H1", "header1"), ("H2", "header2"), ("H3", "header3")]
+    )