| commit | author | age | ||
| d8d3a9 | 1 | from hashlib import md5 |
| 5bf23f | 2 | |
| ee117e | 3 | from pyramid.compat import ( |
| CM | 4 | bytes_, |
| 9c120b | 5 | is_nonstr_iter |
| ee117e | 6 | ) |
| CM | 7 | |
| 5bf23f | 8 | from pyramid.exceptions import ConfigurationError |
| d98612 | 9 | from pyramid.registry import predvalseq |
| CM | 10 | |
| d8d3a9 | 11 | from pyramid.util import ( |
| CM | 12 | TopologicalSorter, |
| 13 | action_method, | |
| 14 | ActionInfo, | |
| 417320 | 15 | takes_one_arg, |
| d8d3a9 | 16 | ) |
| 417320 | 17 | |
| MM | 18 | from pyramid.viewderivers import ( |
| 19 | MAX_ORDER, | |
| 20 | DEFAULT_PHASH, | |
| 21 | ) | |
| d8d3a9 | 22 | |
| CM | 23 | action_method = action_method # support bw compat imports |
| 24 | ActionInfo = ActionInfo # support bw compat imports | |
| 5bf23f | 25 | |
| 417320 | 26 | MAX_ORDER = MAX_ORDER # support bw compat imports |
| MM | 27 | DEFAULT_PHASH = DEFAULT_PHASH # support bw compat imports |
| 28 | ||
| 29 | takes_one_arg = takes_one_arg # support bw compat imports | |
| 561591 | 30 | |
| 32333e | 31 | class not_(object): |
| 49f7c3 | 32 | """ |
| CM | 33 | |
| 34 | You can invert the meaning of any predicate value by wrapping it in a call | |
| 35 | to :class:`pyramid.config.not_`. | |
| 36 | ||
| 37 | .. code-block:: python | |
| 38 | :linenos: | |
| 39 | ||
| 40 | from pyramid.config import not_ | |
| 41 | ||
| 42 | config.add_view( | |
| 43 | 'mypackage.views.my_view', | |
| 44 | route_name='ok', | |
| 45 | request_method=not_('POST') | |
| 46 | ) | |
| 47 | ||
| 48 | The above example will ensure that the view is called if the request method | |
| 49 | is *not* ``POST``, at least if no other view is more specific. | |
| 50 | ||
| 51 | This technique of wrapping a predicate value in ``not_`` can be used | |
| 52 | anywhere predicate values are accepted: | |
| 53 | ||
| 54 | - :meth:`pyramid.config.Configurator.add_view` | |
| 55 | ||
| 56 | - :meth:`pyramid.config.Configurator.add_route` | |
| 57 | ||
| 58 | - :meth:`pyramid.config.Configurator.add_subscriber` | |
| 59 | ||
| 60 | - :meth:`pyramid.view.view_config` | |
| 61 | ||
| 62 | - :meth:`pyramid.events.subscriber` | |
| 63 | ||
| 64 | .. versionadded:: 1.5 | |
| 65 | """ | |
| 32333e | 66 | def __init__(self, value): |
| CM | 67 | self.value = value |
| 68 | ||
| 69 | class Notted(object): | |
| 70 | def __init__(self, predicate): | |
| 71 | self.predicate = predicate | |
| 72 | ||
| 73 | def _notted_text(self, val): | |
| 74 | # if the underlying predicate doesnt return a value, it's not really | |
| 75 | # a predicate, it's just something pretending to be a predicate, | |
| 76 | # so dont update the hash | |
| 77 | if val: | |
| 78 | val = '!' + val | |
| 79 | return val | |
| 80 | ||
| 81 | def text(self): | |
| 82 | return self._notted_text(self.predicate.text()) | |
| 83 | ||
| 84 | def phash(self): | |
| 85 | return self._notted_text(self.predicate.phash()) | |
| 86 | ||
| 87 | def __call__(self, context, request): | |
| 88 | result = self.predicate(context, request) | |
| 89 | phash = self.phash() | |
| 90 | if phash: | |
| 91 | result = not result | |
| 92 | return result | |
| 93 | ||
| fc3f23 | 94 | # under = after |
| CM | 95 | # over = before |
| a00621 | 96 | |
| CM | 97 | class PredicateList(object): |
| 9c8ec5 | 98 | |
| a00621 | 99 | def __init__(self): |
| CM | 100 | self.sorter = TopologicalSorter() |
| 9c8ec5 | 101 | self.last_added = None |
| a00621 | 102 | |
| CM | 103 | def add(self, name, factory, weighs_more_than=None, weighs_less_than=None): |
| 9c8ec5 | 104 | # Predicates should be added to a predicate list in (presumed) |
| CM | 105 | # computation expense order. |
| 106 | ## if weighs_more_than is None and weighs_less_than is None: | |
| 107 | ## weighs_more_than = self.last_added or FIRST | |
| 108 | ## weighs_less_than = LAST | |
| 109 | self.last_added = name | |
| 0ccdc2 | 110 | self.sorter.add( |
| CM | 111 | name, |
| 112 | factory, | |
| 113 | after=weighs_more_than, | |
| 114 | before=weighs_less_than, | |
| 115 | ) | |
| a00621 | 116 | |
| 51ee34 | 117 | def names(self): |
| BJR | 118 | # Return the list of valid predicate names. |
| 119 | return self.sorter.names | |
| 120 | ||
| 9c8ec5 | 121 | def make(self, config, **kw): |
| CM | 122 | # Given a configurator and a list of keywords, a predicate list is |
| 123 | # computed. Elsewhere in the code, we evaluate predicates using a | |
| 124 | # generator expression. All predicates associated with a view or | |
| 125 | # route must evaluate true for the view or route to "match" during a | |
| 126 | # request. The fastest predicate should be evaluated first, then the | |
| 127 | # next fastest, and so on, as if one returns false, the remainder of | |
| 128 | # the predicates won't need to be evaluated. | |
| 129 | # | |
| 130 | # While we compute predicates, we also compute a predicate hash (aka | |
| 131 | # phash) that can be used by a caller to identify identical predicate | |
| 132 | # lists. | |
| a00621 | 133 | ordered = self.sorter.sorted() |
| CM | 134 | phash = md5() |
| 135 | weights = [] | |
| 9c8ec5 | 136 | preds = [] |
| CM | 137 | for n, (name, predicate_factory) in enumerate(ordered): |
| a00621 | 138 | vals = kw.pop(name, None) |
| 9c8ec5 | 139 | if vals is None: # XXX should this be a sentinel other than None? |
| a00621 | 140 | continue |
| 9c8ec5 | 141 | if not isinstance(vals, predvalseq): |
| a00621 | 142 | vals = (vals,) |
| CM | 143 | for val in vals: |
| 32333e | 144 | realval = val |
| CM | 145 | notted = False |
| 146 | if isinstance(val, not_): | |
| 147 | realval = val.value | |
| 148 | notted = True | |
| 149 | pred = predicate_factory(realval, config) | |
| 150 | if notted: | |
| 151 | pred = Notted(pred) | |
| 9c8ec5 | 152 | hashes = pred.phash() |
| a00621 | 153 | if not is_nonstr_iter(hashes): |
| CM | 154 | hashes = [hashes] |
| 155 | for h in hashes: | |
| 156 | phash.update(bytes_(h)) | |
| 25c64c | 157 | weights.append(1 << n + 1) |
| 9c8ec5 | 158 | preds.append(pred) |
| a00621 | 159 | if kw: |
| CM | 160 | raise ConfigurationError('Unknown predicate values: %r' % (kw,)) |
| 9c8ec5 | 161 | # A "order" is computed for the predicate list. An order is |
| CM | 162 | # a scoring. |
| 163 | # | |
| 164 | # Each predicate is associated with a weight value. The weight of a | |
| 165 | # predicate symbolizes the relative potential "importance" of the | |
| 166 | # predicate to all other predicates. A larger weight indicates | |
| 167 | # greater importance. | |
| 168 | # | |
| 169 | # All weights for a given predicate list are bitwise ORed together | |
| 170 | # to create a "score"; this score is then subtracted from | |
| 171 | # MAX_ORDER and divided by an integer representing the number of | |
| 172 | # predicates+1 to determine the order. | |
| 173 | # | |
| 174 | # For views, the order represents the ordering in which a "multiview" | |
| 175 | # ( a collection of views that share the same context/request/name | |
| 176 | # triad but differ in other ways via predicates) will attempt to call | |
| 177 | # its set of views. Views with lower orders will be tried first. | |
| 178 | # The intent is to a) ensure that views with more predicates are | |
| 179 | # always evaluated before views with fewer predicates and b) to | |
| 180 | # ensure a stable call ordering of views that share the same number | |
| 181 | # of predicates. Views which do not have any predicates get an order | |
| 182 | # of MAX_ORDER, meaning that they will be tried very last. | |
| a00621 | 183 | score = 0 |
| CM | 184 | for bit in weights: |
| 185 | score = score | bit | |
| 9c8ec5 | 186 | order = (MAX_ORDER - score) / (len(preds) + 1) |
| CM | 187 | return order, preds, phash.hexdigest() |
