Add accept_charset_property, docs and tests.

1 files changed, 59 insertions, 0 deletions

diff --git a/src/webob/acceptparse.py b/src/webob/acceptparse.py
index db44dce..2844d4a 100644
--- a/src/webob/acceptparse.py
+++ b/src/webob/acceptparse.py
@@ -1191,6 +1191,65 @@ def create_accept_charset_header(header_value):
         return AcceptCharsetInvalidHeader(header_value=header_value)
 
 
+def accept_charset_property():
+    doc = """
+        Property representing the ``Accept-Charset`` header.
+
+        (:rfc:`RFC 7231, section 5.3.3 <7231#section-5.3.3>`)
+
+        The header value in the request environ is parsed and a new object
+        representing the header is created every time we *get* the value of the
+        property. (*set* and *del* change the header value in the request
+        environ, and do not involve parsing.)
+    """
+
+    ENVIRON_KEY = 'HTTP_ACCEPT_CHARSET'
+
+    def fget(request):
+        """Get an object representing the header in the request."""
+        return create_accept_charset_header(
+            header_value=request.environ.get(ENVIRON_KEY)
+        )
+
+    def fset(request, value):
+        """
+        Set the corresponding key in the request environ.
+
+        `value` can be:
+
+        * ``None``
+        * a ``str`` header value
+        * a ``dict``, where keys are charsets and values are qvalues
+        * a ``tuple`` or ``list``, where each item is a charset ``str`` or a
+          ``tuple`` or ``list`` (charset, qvalue) pair (``str``\ s and pairs
+          can be mixed within the ``tuple`` or ``list``)
+        * an :class:`AcceptCharsetValidHeader`, :class:`AcceptCharsetNoHeader`,
+          or :class:`AcceptCharsetInvalidHeader` instance
+        * object of any other type that returns a value for ``__str__``
+        """
+        if value is None or isinstance(value, AcceptCharsetNoHeader):
+            fdel(request=request)
+        else:
+            if isinstance(
+                value, (AcceptCharsetValidHeader, AcceptCharsetInvalidHeader)
+            ):
+                header_value = value.header_value
+            else:
+                header_value = AcceptCharset._python_value_to_header_str(
+                    value=value,
+                )
+            request.environ[ENVIRON_KEY] = header_value
+
+    def fdel(request):
+        """Delete the corresponding key from the request environ."""
+        try:
+            del request.environ[ENVIRON_KEY]
+        except KeyError:
+            pass
+
+    return property(fget, fset, fdel, textwrap.dedent(doc))
+
+
 class AcceptEncoding(object):
     """
     Represent an ``Accept-Encoding`` header.