Fixed #20147 -- Added HttpRequest.headers.

1 files changed, 59 insertions, 0 deletions

diff --git a/django/utils/datastructures.py b/django/utils/datastructures.py
index c5bda0056a..191c2348f6 100644
--- a/django/utils/datastructures.py
+++ b/django/utils/datastructures.py
@@ -1,5 +1,6 @@
 import copy
 from collections import OrderedDict
+from collections.abc import Mapping
 
 
 class OrderedSet:
@@ -280,3 +281,61 @@ class DictWrapper(dict):
         if use_func:
             return self.func(value)
         return value
+
+
+def _destruct_iterable_mapping_values(data):
+    for i, elem in enumerate(data):
+        if len(elem) != 2:
+            raise ValueError(
+                'dictionary update sequence element #{} has '
+                'length {}; 2 is required.'.format(i, len(elem))
+            )
+        if not isinstance(elem[0], str):
+            raise ValueError('Element key %r invalid, only strings are allowed' % elem[0])
+        yield tuple(elem)
+
+
+class CaseInsensitiveMapping(Mapping):
+    """
+    Mapping allowing case-insensitive key lookups. Original case of keys is
+    preserved for iteration and string representation.
+
+    Example::
+
+        >>> ci_map = CaseInsensitiveMapping({'name': 'Jane'})
+        >>> ci_map['Name']
+        Jane
+        >>> ci_map['NAME']
+        Jane
+        >>> ci_map['name']
+        Jane
+        >>> ci_map  # original case preserved
+        {'name': 'Jane'}
+    """
+
+    def __init__(self, data):
+        if not isinstance(data, Mapping):
+            data = {k: v for k, v in _destruct_iterable_mapping_values(data)}
+        self._store = {k.lower(): (k, v) for k, v in data.items()}
+
+    def __getitem__(self, key):
+        return self._store[key.lower()][1]
+
+    def __len__(self):
+        return len(self._store)
+
+    def __eq__(self, other):
+        return isinstance(other, Mapping) and {
+            k.lower(): v for k, v in self.items()
+        } == {
+            k.lower(): v for k, v in other.items()
+        }
+
+    def __iter__(self):
+        return (original_key for original_key, value in self._store.values())
+
+    def __repr__(self):
+        return repr({key: value for key, value in self._store.values()})
+
+    def copy(self):
+        return self