add code for analysis of data

1 files changed, 831 insertions, 0 deletions

diff --git a/venv/lib/python3.8/site-packages/werkzeug/wrappers/response.py b/venv/lib/python3.8/site-packages/werkzeug/wrappers/response.py
new file mode 100644
index 0000000..7f01287
--- /dev/null
+++ b/venv/lib/python3.8/site-packages/werkzeug/wrappers/response.py
@@ -0,0 +1,831 @@
+from __future__ import annotations
+
+import json
+import typing as t
+from http import HTTPStatus
+from urllib.parse import urljoin
+
+from .._internal import _get_environ
+from ..datastructures import Headers
+from ..http import generate_etag
+from ..http import http_date
+from ..http import is_resource_modified
+from ..http import parse_etags
+from ..http import parse_range_header
+from ..http import remove_entity_headers
+from ..sansio.response import Response as _SansIOResponse
+from ..urls import iri_to_uri
+from ..utils import cached_property
+from ..wsgi import _RangeWrapper
+from ..wsgi import ClosingIterator
+from ..wsgi import get_current_url
+
+if t.TYPE_CHECKING:
+    from _typeshed.wsgi import StartResponse
+    from _typeshed.wsgi import WSGIApplication
+    from _typeshed.wsgi import WSGIEnvironment
+
+    from .request import Request
+
+
+def _iter_encoded(iterable: t.Iterable[str | bytes]) -> t.Iterator[bytes]:
+    for item in iterable:
+        if isinstance(item, str):
+            yield item.encode()
+        else:
+            yield item
+
+
+class Response(_SansIOResponse):
+    """Represents an outgoing WSGI HTTP response with body, status, and
+    headers. Has properties and methods for using the functionality
+    defined by various HTTP specs.
+
+    The response body is flexible to support different use cases. The
+    simple form is passing bytes, or a string which will be encoded as
+    UTF-8. Passing an iterable of bytes or strings makes this a
+    streaming response. A generator is particularly useful for building
+    a CSV file in memory or using SSE (Server Sent Events). A file-like
+    object is also iterable, although the
+    :func:`~werkzeug.utils.send_file` helper should be used in that
+    case.
+
+    The response object is itself a WSGI application callable. When
+    called (:meth:`__call__`) with ``environ`` and ``start_response``,
+    it will pass its status and headers to ``start_response`` then
+    return its body as an iterable.
+
+    .. code-block:: python
+
+        from werkzeug.wrappers.response import Response
+
+        def index():
+            return Response("Hello, World!")
+
+        def application(environ, start_response):
+            path = environ.get("PATH_INFO") or "/"
+
+            if path == "/":
+                response = index()
+            else:
+                response = Response("Not Found", status=404)
+
+            return response(environ, start_response)
+
+    :param response: The data for the body of the response. A string or
+        bytes, or tuple or list of strings or bytes, for a fixed-length
+        response, or any other iterable of strings or bytes for a
+        streaming response. Defaults to an empty body.
+    :param status: The status code for the response. Either an int, in
+        which case the default status message is added, or a string in
+        the form ``{code} {message}``, like ``404 Not Found``. Defaults
+        to 200.
+    :param headers: A :class:`~werkzeug.datastructures.Headers` object,
+        or a list of ``(key, value)`` tuples that will be converted to a
+        ``Headers`` object.
+    :param mimetype: The mime type (content type without charset or
+        other parameters) of the response. If the value starts with
+        ``text/`` (or matches some other special cases), the charset
+        will be added to create the ``content_type``.
+    :param content_type: The full content type of the response.
+        Overrides building the value from ``mimetype``.
+    :param direct_passthrough: Pass the response body directly through
+        as the WSGI iterable. This can be used when the body is a binary
+        file or other iterator of bytes, to skip some unnecessary
+        checks. Use :func:`~werkzeug.utils.send_file` instead of setting
+        this manually.
+
+    .. versionchanged:: 2.1
+        Old ``BaseResponse`` and mixin classes were removed.
+
+    .. versionchanged:: 2.0
+        Combine ``BaseResponse`` and mixins into a single ``Response``
+        class.
+
+    .. versionchanged:: 0.5
+        The ``direct_passthrough`` parameter was added.
+    """
+
+    #: if set to `False` accessing properties on the response object will
+    #: not try to consume the response iterator and convert it into a list.
+    #:
+    #: .. versionadded:: 0.6.2
+    #:
+    #:    That attribute was previously called `implicit_seqence_conversion`.
+    #:    (Notice the typo).  If you did use this feature, you have to adapt
+    #:    your code to the name change.
+    implicit_sequence_conversion = True
+
+    #: If a redirect ``Location`` header is a relative URL, make it an
+    #: absolute URL, including scheme and domain.
+    #:
+    #: .. versionchanged:: 2.1
+    #:     This is disabled by default, so responses will send relative
+    #:     redirects.
+    #:
+    #: .. versionadded:: 0.8
+    autocorrect_location_header = False
+
+    #: Should this response object automatically set the content-length
+    #: header if possible?  This is true by default.
+    #:
+    #: .. versionadded:: 0.8
+    automatically_set_content_length = True
+
+    #: The response body to send as the WSGI iterable. A list of strings
+    #: or bytes represents a fixed-length response, any other iterable
+    #: is a streaming response. Strings are encoded to bytes as UTF-8.
+    #:
+    #: Do not set to a plain string or bytes, that will cause sending
+    #: the response to be very inefficient as it will iterate one byte
+    #: at a time.
+    response: t.Iterable[str] | t.Iterable[bytes]
+
+    def __init__(
+        self,
+        response: t.Iterable[bytes] | bytes | t.Iterable[str] | str | None = None,
+        status: int | str | HTTPStatus | None = None,
+        headers: t.Mapping[str, str | t.Iterable[str]]
+        | t.Iterable[tuple[str, str]]
+        | None = None,
+        mimetype: str | None = None,
+        content_type: str | None = None,
+        direct_passthrough: bool = False,
+    ) -> None:
+        super().__init__(
+            status=status,
+            headers=headers,
+            mimetype=mimetype,
+            content_type=content_type,
+        )
+
+        #: Pass the response body directly through as the WSGI iterable.
+        #: This can be used when the body is a binary file or other
+        #: iterator of bytes, to skip some unnecessary checks. Use
+        #: :func:`~werkzeug.utils.send_file` instead of setting this
+        #: manually.
+        self.direct_passthrough = direct_passthrough
+        self._on_close: list[t.Callable[[], t.Any]] = []
+
+        # we set the response after the headers so that if a class changes
+        # the charset attribute, the data is set in the correct charset.
+        if response is None:
+            self.response = []
+        elif isinstance(response, (str, bytes, bytearray)):
+            self.set_data(response)
+        else:
+            self.response = response
+
+    def call_on_close(self, func: t.Callable[[], t.Any]) -> t.Callable[[], t.Any]:
+        """Adds a function to the internal list of functions that should
+        be called as part of closing down the response.  Since 0.7 this
+        function also returns the function that was passed so that this
+        can be used as a decorator.
+
+        .. versionadded:: 0.6
+        """
+        self._on_close.append(func)
+        return func
+
+    def __repr__(self) -> str:
+        if self.is_sequence:
+            body_info = f"{sum(map(len, self.iter_encoded()))} bytes"
+        else:
+            body_info = "streamed" if self.is_streamed else "likely-streamed"
+        return f"<{type(self).__name__} {body_info} [{self.status}]>"
+
+    @classmethod
+    def force_type(
+        cls, response: Response, environ: WSGIEnvironment | None = None
+    ) -> Response:
+        """Enforce that the WSGI response is a response object of the current
+        type.  Werkzeug will use the :class:`Response` internally in many
+        situations like the exceptions.  If you call :meth:`get_response` on an
+        exception you will get back a regular :class:`Response` object, even
+        if you are using a custom subclass.
+
+        This method can enforce a given response type, and it will also
+        convert arbitrary WSGI callables into response objects if an environ
+        is provided::
+
+            # convert a Werkzeug response object into an instance of the
+            # MyResponseClass subclass.
+            response = MyResponseClass.force_type(response)
+
+            # convert any WSGI application into a response object
+            response = MyResponseClass.force_type(response, environ)
+
+        This is especially useful if you want to post-process responses in
+        the main dispatcher and use functionality provided by your subclass.
+
+        Keep in mind that this will modify response objects in place if
+        possible!
+
+        :param response: a response object or wsgi application.
+        :param environ: a WSGI environment object.
+        :return: a response object.
+        """
+        if not isinstance(response, Response):
+            if environ is None:
+                raise TypeError(
+                    "cannot convert WSGI application into response"
+                    " objects without an environ"
+                )
+
+            from ..test import run_wsgi_app
+
+            response = Response(*run_wsgi_app(response, environ))
+
+        response.__class__ = cls
+        return response
+
+    @classmethod
+    def from_app(
+        cls, app: WSGIApplication, environ: WSGIEnvironment, buffered: bool = False
+    ) -> Response:
+        """Create a new response object from an application output.  This
+        works best if you pass it an application that returns a generator all
+        the time.  Sometimes applications may use the `write()` callable
+        returned by the `start_response` function.  This tries to resolve such
+        edge cases automatically.  But if you don't get the expected output
+        you should set `buffered` to `True` which enforces buffering.
+
+        :param app: the WSGI application to execute.
+        :param environ: the WSGI environment to execute against.
+        :param buffered: set to `True` to enforce buffering.
+        :return: a response object.
+        """
+        from ..test import run_wsgi_app
+
+        return cls(*run_wsgi_app(app, environ, buffered))
+
+    @t.overload
+    def get_data(self, as_text: t.Literal[False] = False) -> bytes: ...
+
+    @t.overload
+    def get_data(self, as_text: t.Literal[True]) -> str: ...
+
+    def get_data(self, as_text: bool = False) -> bytes | str:
+        """The string representation of the response body.  Whenever you call
+        this property the response iterable is encoded and flattened.  This
+        can lead to unwanted behavior if you stream big data.
+
+        This behavior can be disabled by setting
+        :attr:`implicit_sequence_conversion` to `False`.
+
+        If `as_text` is set to `True` the return value will be a decoded
+        string.
+
+        .. versionadded:: 0.9
+        """
+        self._ensure_sequence()
+        rv = b"".join(self.iter_encoded())
+
+        if as_text:
+            return rv.decode()
+
+        return rv
+
+    def set_data(self, value: bytes | str) -> None:
+        """Sets a new string as response.  The value must be a string or
+        bytes. If a string is set it's encoded to the charset of the
+        response (utf-8 by default).
+
+        .. versionadded:: 0.9
+        """
+        if isinstance(value, str):
+            value = value.encode()
+        self.response = [value]
+        if self.automatically_set_content_length:
+            self.headers["Content-Length"] = str(len(value))
+
+    data = property(
+        get_data,
+        set_data,
+        doc="A descriptor that calls :meth:`get_data` and :meth:`set_data`.",
+    )
+
+    def calculate_content_length(self) -> int | None:
+        """Returns the content length if available or `None` otherwise."""
+        try:
+            self._ensure_sequence()
+        except RuntimeError:
+            return None
+        return sum(len(x) for x in self.iter_encoded())
+
+    def _ensure_sequence(self, mutable: bool = False) -> None:
+        """This method can be called by methods that need a sequence.  If
+        `mutable` is true, it will also ensure that the response sequence
+        is a standard Python list.
+
+        .. versionadded:: 0.6
+        """
+        if self.is_sequence:
+            # if we need a mutable object, we ensure it's a list.
+            if mutable and not isinstance(self.response, list):
+                self.response = list(self.response)  # type: ignore
+            return
+        if self.direct_passthrough:
+            raise RuntimeError(
+                "Attempted implicit sequence conversion but the"
+                " response object is in direct passthrough mode."
+            )
+        if not self.implicit_sequence_conversion:
+            raise RuntimeError(
+                "The response object required the iterable to be a"
+                " sequence, but the implicit conversion was disabled."
+                " Call make_sequence() yourself."
+            )
+        self.make_sequence()
+
+    def make_sequence(self) -> None:
+        """Converts the response iterator in a list.  By default this happens
+        automatically if required.  If `implicit_sequence_conversion` is
+        disabled, this method is not automatically called and some properties
+        might raise exceptions.  This also encodes all the items.
+
+        .. versionadded:: 0.6
+        """
+        if not self.is_sequence:
+            # if we consume an iterable we have to ensure that the close
+            # method of the iterable is called if available when we tear
+            # down the response
+            close = getattr(self.response, "close", None)
+            self.response = list(self.iter_encoded())
+            if close is not None:
+                self.call_on_close(close)
+
+    def iter_encoded(self) -> t.Iterator[bytes]:
+        """Iter the response encoded with the encoding of the response.
+        If the response object is invoked as WSGI application the return
+        value of this method is used as application iterator unless
+        :attr:`direct_passthrough` was activated.
+        """
+        # Encode in a separate function so that self.response is fetched
+        # early.  This allows us to wrap the response with the return
+        # value from get_app_iter or iter_encoded.
+        return _iter_encoded(self.response)
+
+    @property
+    def is_streamed(self) -> bool:
+        """If the response is streamed (the response is not an iterable with
+        a length information) this property is `True`.  In this case streamed
+        means that there is no information about the number of iterations.
+        This is usually `True` if a generator is passed to the response object.
+
+        This is useful for checking before applying some sort of post
+        filtering that should not take place for streamed responses.
+        """
+        try:
+            len(self.response)  # type: ignore
+        except (TypeError, AttributeError):
+            return True
+        return False
+
+    @property
+    def is_sequence(self) -> bool:
+        """If the iterator is buffered, this property will be `True`.  A
+        response object will consider an iterator to be buffered if the
+        response attribute is a list or tuple.
+
+        .. versionadded:: 0.6
+        """
+        return isinstance(self.response, (tuple, list))
+
+    def close(self) -> None:
+        """Close the wrapped response if possible.  You can also use the object
+        in a with statement which will automatically close it.
+
+        .. versionadded:: 0.9
+           Can now be used in a with statement.
+        """
+        if hasattr(self.response, "close"):
+            self.response.close()
+        for func in self._on_close:
+            func()
+
+    def __enter__(self) -> Response:
+        return self
+
+    def __exit__(self, exc_type, exc_value, tb):  # type: ignore
+        self.close()
+
+    def freeze(self) -> None:
+        """Make the response object ready to be pickled. Does the
+        following:
+
+        *   Buffer the response into a list, ignoring
+            :attr:`implicity_sequence_conversion` and
+            :attr:`direct_passthrough`.
+        *   Set the ``Content-Length`` header.
+        *   Generate an ``ETag`` header if one is not already set.
+
+        .. versionchanged:: 2.1
+            Removed the ``no_etag`` parameter.
+
+        .. versionchanged:: 2.0
+            An ``ETag`` header is always added.
+
+        .. versionchanged:: 0.6
+            The ``Content-Length`` header is set.
+        """
+        # Always freeze the encoded response body, ignore
+        # implicit_sequence_conversion and direct_passthrough.
+        self.response = list(self.iter_encoded())
+        self.headers["Content-Length"] = str(sum(map(len, self.response)))
+        self.add_etag()
+
+    def get_wsgi_headers(self, environ: WSGIEnvironment) -> Headers:
+        """This is automatically called right before the response is started
+        and returns headers modified for the given environment.  It returns a
+        copy of the headers from the response with some modifications applied
+        if necessary.
+
+        For example the location header (if present) is joined with the root
+        URL of the environment.  Also the content length is automatically set
+        to zero here for certain status codes.
+
+        .. versionchanged:: 0.6
+           Previously that function was called `fix_headers` and modified
+           the response object in place.  Also since 0.6, IRIs in location
+           and content-location headers are handled properly.
+
+           Also starting with 0.6, Werkzeug will attempt to set the content
+           length if it is able to figure it out on its own.  This is the
+           case if all the strings in the response iterable are already
+           encoded and the iterable is buffered.
+
+        :param environ: the WSGI environment of the request.
+        :return: returns a new :class:`~werkzeug.datastructures.Headers`
+                 object.
+        """
+        headers = Headers(self.headers)
+        location: str | None = None
+        content_location: str | None = None
+        content_length: str | int | None = None
+        status = self.status_code
+
+        # iterate over the headers to find all values in one go.  Because
+        # get_wsgi_headers is used each response that gives us a tiny
+        # speedup.
+        for key, value in headers:
+            ikey = key.lower()
+            if ikey == "location":
+                location = value
+            elif ikey == "content-location":
+                content_location = value
+            elif ikey == "content-length":
+                content_length = value
+
+        if location is not None:
+            location = iri_to_uri(location)
+
+            if self.autocorrect_location_header:
+                # Make the location header an absolute URL.
+                current_url = get_current_url(environ, strip_querystring=True)
+                current_url = iri_to_uri(current_url)
+                location = urljoin(current_url, location)
+
+            headers["Location"] = location
+
+        # make sure the content location is a URL
+        if content_location is not None:
+            headers["Content-Location"] = iri_to_uri(content_location)
+
+        if 100 <= status < 200 or status == 204:
+            # Per section 3.3.2 of RFC 7230, "a server MUST NOT send a
+            # Content-Length header field in any response with a status
+            # code of 1xx (Informational) or 204 (No Content)."
+            headers.remove("Content-Length")
+        elif status == 304:
+            remove_entity_headers(headers)
+
+        # if we can determine the content length automatically, we
+        # should try to do that.  But only if this does not involve
+        # flattening the iterator or encoding of strings in the
+        # response. We however should not do that if we have a 304
+        # response.
+        if (
+            self.automatically_set_content_length
+            and self.is_sequence
+            and content_length is None
+            and status not in (204, 304)
+            and not (100 <= status < 200)
+        ):
+            content_length = sum(len(x) for x in self.iter_encoded())
+            headers["Content-Length"] = str(content_length)
+
+        return headers
+
+    def get_app_iter(self, environ: WSGIEnvironment) -> t.Iterable[bytes]:
+        """Returns the application iterator for the given environ.  Depending
+        on the request method and the current status code the return value
+        might be an empty response rather than the one from the response.
+
+        If the request method is `HEAD` or the status code is in a range
+        where the HTTP specification requires an empty response, an empty
+        iterable is returned.
+
+        .. versionadded:: 0.6
+
+        :param environ: the WSGI environment of the request.
+        :return: a response iterable.
+        """
+        status = self.status_code
+        if (
+            environ["REQUEST_METHOD"] == "HEAD"
+            or 100 <= status < 200
+            or status in (204, 304)
+        ):
+            iterable: t.Iterable[bytes] = ()
+        elif self.direct_passthrough:
+            return self.response  # type: ignore
+        else:
+            iterable = self.iter_encoded()
+        return ClosingIterator(iterable, self.close)
+
+    def get_wsgi_response(
+        self, environ: WSGIEnvironment
+    ) -> tuple[t.Iterable[bytes], str, list[tuple[str, str]]]:
+        """Returns the final WSGI response as tuple.  The first item in
+        the tuple is the application iterator, the second the status and
+        the third the list of headers.  The response returned is created
+        specially for the given environment.  For example if the request
+        method in the WSGI environment is ``'HEAD'`` the response will
+        be empty and only the headers and status code will be present.
+
+        .. versionadded:: 0.6
+
+        :param environ: the WSGI environment of the request.
+        :return: an ``(app_iter, status, headers)`` tuple.
+        """
+        headers = self.get_wsgi_headers(environ)
+        app_iter = self.get_app_iter(environ)
+        return app_iter, self.status, headers.to_wsgi_list()
+
+    def __call__(
+        self, environ: WSGIEnvironment, start_response: StartResponse
+    ) -> t.Iterable[bytes]:
+        """Process this response as WSGI application.
+
+        :param environ: the WSGI environment.
+        :param start_response: the response callable provided by the WSGI
+                               server.
+        :return: an application iterator
+        """
+        app_iter, status, headers = self.get_wsgi_response(environ)
+        start_response(status, headers)
+        return app_iter
+
+    # JSON
+
+    #: A module or other object that has ``dumps`` and ``loads``
+    #: functions that match the API of the built-in :mod:`json` module.
+    json_module = json
+
+    @property
+    def json(self) -> t.Any | None:
+        """The parsed JSON data if :attr:`mimetype` indicates JSON
+        (:mimetype:`application/json`, see :attr:`is_json`).
+
+        Calls :meth:`get_json` with default arguments.
+        """
+        return self.get_json()
+
+    @t.overload
+    def get_json(self, force: bool = ..., silent: t.Literal[False] = ...) -> t.Any: ...
+
+    @t.overload
+    def get_json(self, force: bool = ..., silent: bool = ...) -> t.Any | None: ...
+
+    def get_json(self, force: bool = False, silent: bool = False) -> t.Any | None:
+        """Parse :attr:`data` as JSON. Useful during testing.
+
+        If the mimetype does not indicate JSON
+        (:mimetype:`application/json`, see :attr:`is_json`), this
+        returns ``None``.
+
+        Unlike :meth:`Request.get_json`, the result is not cached.
+
+        :param force: Ignore the mimetype and always try to parse JSON.
+        :param silent: Silence parsing errors and return ``None``
+            instead.
+        """
+        if not (force or self.is_json):
+            return None
+
+        data = self.get_data()
+
+        try:
+            return self.json_module.loads(data)
+        except ValueError:
+            if not silent:
+                raise
+
+            return None
+
+    # Stream
+
+    @cached_property
+    def stream(self) -> ResponseStream:
+        """The response iterable as write-only stream."""
+        return ResponseStream(self)
+
+    def _wrap_range_response(self, start: int, length: int) -> None:
+        """Wrap existing Response in case of Range Request context."""
+        if self.status_code == 206:
+            self.response = _RangeWrapper(self.response, start, length)  # type: ignore
+
+    def _is_range_request_processable(self, environ: WSGIEnvironment) -> bool:
+        """Return ``True`` if `Range` header is present and if underlying
+        resource is considered unchanged when compared with `If-Range` header.
+        """
+        return (
+            "HTTP_IF_RANGE" not in environ
+            or not is_resource_modified(
+                environ,
+                self.headers.get("etag"),
+                None,
+                self.headers.get("last-modified"),
+                ignore_if_range=False,
+            )
+        ) and "HTTP_RANGE" in environ
+
+    def _process_range_request(
+        self,
+        environ: WSGIEnvironment,
+        complete_length: int | None,
+        accept_ranges: bool | str,
+    ) -> bool:
+        """Handle Range Request related headers (RFC7233).  If `Accept-Ranges`
+        header is valid, and Range Request is processable, we set the headers
+        as described by the RFC, and wrap the underlying response in a
+        RangeWrapper.
+
+        Returns ``True`` if Range Request can be fulfilled, ``False`` otherwise.
+
+        :raises: :class:`~werkzeug.exceptions.RequestedRangeNotSatisfiable`
+                 if `Range` header could not be parsed or satisfied.
+
+        .. versionchanged:: 2.0
+            Returns ``False`` if the length is 0.
+        """
+        from ..exceptions import RequestedRangeNotSatisfiable
+
+        if (
+            not accept_ranges
+            or complete_length is None
+            or complete_length == 0
+            or not self._is_range_request_processable(environ)
+        ):
+            return False
+
+        if accept_ranges is True:
+            accept_ranges = "bytes"
+
+        parsed_range = parse_range_header(environ.get("HTTP_RANGE"))
+
+        if parsed_range is None:
+            raise RequestedRangeNotSatisfiable(complete_length)
+
+        range_tuple = parsed_range.range_for_length(complete_length)
+        content_range_header = parsed_range.to_content_range_header(complete_length)
+
+        if range_tuple is None or content_range_header is None:
+            raise RequestedRangeNotSatisfiable(complete_length)
+
+        content_length = range_tuple[1] - range_tuple[0]
+        self.headers["Content-Length"] = str(content_length)
+        self.headers["Accept-Ranges"] = accept_ranges
+        self.content_range = content_range_header  # type: ignore
+        self.status_code = 206
+        self._wrap_range_response(range_tuple[0], content_length)
+        return True
+
+    def make_conditional(
+        self,
+        request_or_environ: WSGIEnvironment | Request,
+        accept_ranges: bool | str = False,
+        complete_length: int | None = None,
+    ) -> Response:
+        """Make the response conditional to the request.  This method works
+        best if an etag was defined for the response already.  The `add_etag`
+        method can be used to do that.  If called without etag just the date
+        header is set.
+
+        This does nothing if the request method in the request or environ is
+        anything but GET or HEAD.
+
+        For optimal performance when handling range requests, it's recommended
+        that your response data object implements `seekable`, `seek` and `tell`
+        methods as described by :py:class:`io.IOBase`.  Objects returned by
+        :meth:`~werkzeug.wsgi.wrap_file` automatically implement those methods.
+
+        It does not remove the body of the response because that's something
+        the :meth:`__call__` function does for us automatically.
+
+        Returns self so that you can do ``return resp.make_conditional(req)``
+        but modifies the object in-place.
+
+        :param request_or_environ: a request object or WSGI environment to be
+                                   used to make the response conditional
+                                   against.
+        :param accept_ranges: This parameter dictates the value of
+                              `Accept-Ranges` header. If ``False`` (default),
+                              the header is not set. If ``True``, it will be set
+                              to ``"bytes"``. If it's a string, it will use this
+                              value.
+        :param complete_length: Will be used only in valid Range Requests.
+                                It will set `Content-Range` complete length
+                                value and compute `Content-Length` real value.
+                                This parameter is mandatory for successful
+                                Range Requests completion.
+        :raises: :class:`~werkzeug.exceptions.RequestedRangeNotSatisfiable`
+                 if `Range` header could not be parsed or satisfied.
+
+        .. versionchanged:: 2.0
+            Range processing is skipped if length is 0 instead of
+            raising a 416 Range Not Satisfiable error.
+        """
+        environ = _get_environ(request_or_environ)
+        if environ["REQUEST_METHOD"] in ("GET", "HEAD"):
+            # if the date is not in the headers, add it now.  We however
+            # will not override an already existing header.  Unfortunately
+            # this header will be overridden by many WSGI servers including
+            # wsgiref.
+            if "date" not in self.headers:
+                self.headers["Date"] = http_date()
+            is206 = self._process_range_request(environ, complete_length, accept_ranges)
+            if not is206 and not is_resource_modified(
+                environ,
+                self.headers.get("etag"),
+                None,
+                self.headers.get("last-modified"),
+            ):
+                if parse_etags(environ.get("HTTP_IF_MATCH")):
+                    self.status_code = 412
+                else:
+                    self.status_code = 304
+            if (
+                self.automatically_set_content_length
+                and "content-length" not in self.headers
+            ):
+                length = self.calculate_content_length()
+                if length is not None:
+                    self.headers["Content-Length"] = str(length)
+        return self
+
+    def add_etag(self, overwrite: bool = False, weak: bool = False) -> None:
+        """Add an etag for the current response if there is none yet.
+
+        .. versionchanged:: 2.0
+            SHA-1 is used to generate the value. MD5 may not be
+            available in some environments.
+        """
+        if overwrite or "etag" not in self.headers:
+            self.set_etag(generate_etag(self.get_data()), weak)
+
+
+class ResponseStream:
+    """A file descriptor like object used by :meth:`Response.stream` to
+    represent the body of the stream. It directly pushes into the
+    response iterable of the response object.
+    """
+
+    mode = "wb+"
+
+    def __init__(self, response: Response):
+        self.response = response
+        self.closed = False
+
+    def write(self, value: bytes) -> int:
+        if self.closed:
+            raise ValueError("I/O operation on closed file")
+        self.response._ensure_sequence(mutable=True)
+        self.response.response.append(value)  # type: ignore
+        self.response.headers.pop("Content-Length", None)
+        return len(value)
+
+    def writelines(self, seq: t.Iterable[bytes]) -> None:
+        for item in seq:
+            self.write(item)
+
+    def close(self) -> None:
+        self.closed = True
+
+    def flush(self) -> None:
+        if self.closed:
+            raise ValueError("I/O operation on closed file")
+
+    def isatty(self) -> bool:
+        if self.closed:
+            raise ValueError("I/O operation on closed file")
+        return False
+
+    def tell(self) -> int:
+        self.response._ensure_sequence()
+        return sum(map(len, self.response.response))
+
+    @property
+    def encoding(self) -> str:
+        return "utf-8"