codekingpro/portable-devtools

1from __future__ import annotations2 3from .mixins import ImmutableDictMixin4from .mixins import UpdateDictMixin5 6 7def cache_control_property(key, empty, type):8    """Return a new property object for a cache header. Useful if you9    want to add support for a cache extension in a subclass.10 11    .. versionchanged:: 2.012        Renamed from ``cache_property``.13    """14    return property(15        lambda x: x._get_cache_value(key, empty, type),16        lambda x, v: x._set_cache_value(key, v, type),17        lambda x: x._del_cache_value(key),18        f"accessor for {key!r}",19    )20 21 22class _CacheControl(UpdateDictMixin, dict):23    """Subclass of a dict that stores values for a Cache-Control header.  It24    has accessors for all the cache-control directives specified in RFC 2616.25    The class does not differentiate between request and response directives.26 27    Because the cache-control directives in the HTTP header use dashes the28    python descriptors use underscores for that.29 30    To get a header of the :class:`CacheControl` object again you can convert31    the object into a string or call the :meth:`to_header` method.  If you plan32    to subclass it and add your own items have a look at the sourcecode for33    that class.34 35    .. versionchanged:: 2.1.036        Setting int properties such as ``max_age`` will convert the37        value to an int.38 39    .. versionchanged:: 0.440 41       Setting `no_cache` or `private` to boolean `True` will set the implicit42       none-value which is ``*``:43 44       >>> cc = ResponseCacheControl()45       >>> cc.no_cache = True46       >>> cc47       <ResponseCacheControl 'no-cache'>48       >>> cc.no_cache49       '*'50       >>> cc.no_cache = None51       >>> cc52       <ResponseCacheControl ''>53 54       In versions before 0.5 the behavior documented here affected the now55       no longer existing `CacheControl` class.56    """57 58    no_cache = cache_control_property("no-cache", "*", None)59    no_store = cache_control_property("no-store", None, bool)60    max_age = cache_control_property("max-age", -1, int)61    no_transform = cache_control_property("no-transform", None, None)62 63    def __init__(self, values=(), on_update=None):64        dict.__init__(self, values or ())65        self.on_update = on_update66        self.provided = values is not None67 68    def _get_cache_value(self, key, empty, type):69        """Used internally by the accessor properties."""70        if type is bool:71            return key in self72        if key in self:73            value = self[key]74            if value is None:75                return empty76            elif type is not None:77                try:78                    value = type(value)79                except ValueError:80                    pass81            return value82        return None83 84    def _set_cache_value(self, key, value, type):85        """Used internally by the accessor properties."""86        if type is bool:87            if value:88                self[key] = None89            else:90                self.pop(key, None)91        else:92            if value is None:93                self.pop(key, None)94            elif value is True:95                self[key] = None96            else:97                if type is not None:98                    self[key] = type(value)99                else:100                    self[key] = value101 102    def _del_cache_value(self, key):103        """Used internally by the accessor properties."""104        if key in self:105            del self[key]106 107    def to_header(self):108        """Convert the stored values into a cache control header."""109        return http.dump_header(self)110 111    def __str__(self):112        return self.to_header()113 114    def __repr__(self):115        kv_str = " ".join(f"{k}={v!r}" for k, v in sorted(self.items()))116        return f"<{type(self).__name__} {kv_str}>"117 118    cache_property = staticmethod(cache_control_property)119 120 121class RequestCacheControl(ImmutableDictMixin, _CacheControl):122    """A cache control for requests.  This is immutable and gives access123    to all the request-relevant cache control headers.124 125    To get a header of the :class:`RequestCacheControl` object again you can126    convert the object into a string or call the :meth:`to_header` method.  If127    you plan to subclass it and add your own items have a look at the sourcecode128    for that class.129 130    .. versionchanged:: 2.1.0131        Setting int properties such as ``max_age`` will convert the132        value to an int.133 134    .. versionadded:: 0.5135       In previous versions a `CacheControl` class existed that was used136       both for request and response.137    """138 139    max_stale = cache_control_property("max-stale", "*", int)140    min_fresh = cache_control_property("min-fresh", "*", int)141    only_if_cached = cache_control_property("only-if-cached", None, bool)142 143 144class ResponseCacheControl(_CacheControl):145    """A cache control for responses.  Unlike :class:`RequestCacheControl`146    this is mutable and gives access to response-relevant cache control147    headers.148 149    To get a header of the :class:`ResponseCacheControl` object again you can150    convert the object into a string or call the :meth:`to_header` method.  If151    you plan to subclass it and add your own items have a look at the sourcecode152    for that class.153 154    .. versionchanged:: 2.1.1155        ``s_maxage`` converts the value to an int.156 157    .. versionchanged:: 2.1.0158        Setting int properties such as ``max_age`` will convert the159        value to an int.160 161    .. versionadded:: 0.5162       In previous versions a `CacheControl` class existed that was used163       both for request and response.164    """165 166    public = cache_control_property("public", None, bool)167    private = cache_control_property("private", "*", None)168    must_revalidate = cache_control_property("must-revalidate", None, bool)169    proxy_revalidate = cache_control_property("proxy-revalidate", None, bool)170    s_maxage = cache_control_property("s-maxage", None, int)171    immutable = cache_control_property("immutable", None, bool)172 173 174# circular dependencies175from .. import http176