Add 'merge' method to HTTPHeaderMap.

Author: Lukasa

hyper/common/headers.py

@@ -181,6 +181,22 @@ def iter_raw(self):
         for item in self._items:
             yield item
 
+    def merge(self, other):
+        """
+        Merge another header set or any other dict-like into this one.
+        """
+        # Short circuit to avoid infinite loops in case we try to merge into
+        # ourselves.
+        if other is self:
+            return
+
+        if isinstance(other, HTTPHeaderMap):
+            self._items.extend(other.iter_raw())
+            return
+
+        for k, v in other.items():
+            self._items.append(to_bytestring_tuple(k, v))
+
     def __eq__(self, other):
         return self._items == other._items
 

test/test_headers.py

@@ -226,3 +226,35 @@ def test_headers_must_be_strings(self):
 
         with pytest.raises(ValueError):
             h[1] = 'v'
+
+    def test_merge_self_is_no_op(self):
+        h = HTTPHeaderMap([(b'hi', b'there')])
+        h.merge(h)
+
+        assert h == HTTPHeaderMap([(b'hi', b'there')])
+
+    def test_merge_headermaps_preserves_raw(self):
+        h1 = HTTPHeaderMap([
+            (b'hi', b'there')
+        ])
+        h2 = HTTPHeaderMap([
+            (b'Hi', b'there, sir, maam')
+        ])
+
+        h1.merge(h2)
+
+        assert list(h1.iter_raw()) == [
+            (b'hi', b'there'),
+            (b'Hi', b'there, sir, maam'),
+        ]
+
+    def test_merge_header_map_dict(self):
+        h = HTTPHeaderMap([(b'hi', b'there')])
+        d = {'cat': 'dog'}
+
+        h.merge(d)
+
+        assert list(h.items()) == [
+            (b'hi', b'there'),
+            (b'cat', b'dog'),
+        ]