R David Murray | 0b6f6c8 | 2012-05-25 18:42:14 -0400 | [diff] [blame] | 1 | """Representing and manipulating email headers via custom objects. |
| 2 | |
| 3 | This module provides an implementation of the HeaderRegistry API. |
| 4 | The implementation is designed to flexibly follow RFC5322 rules. |
| 5 | |
| 6 | Eventually HeaderRegistry will be a public API, but it isn't yet, |
| 7 | and will probably change some before that happens. |
| 8 | |
| 9 | """ |
R David Murray | 685b349 | 2014-10-17 19:30:13 -0400 | [diff] [blame] | 10 | from types import MappingProxyType |
R David Murray | 0b6f6c8 | 2012-05-25 18:42:14 -0400 | [diff] [blame] | 11 | |
| 12 | from email import utils |
| 13 | from email import errors |
| 14 | from email import _header_value_parser as parser |
| 15 | |
| 16 | class Address: |
| 17 | |
| 18 | def __init__(self, display_name='', username='', domain='', addr_spec=None): |
Martin Panter | 96a4f07 | 2016-02-10 01:17:51 +0000 | [diff] [blame] | 19 | """Create an object representing a full email address. |
R David Murray | 0b6f6c8 | 2012-05-25 18:42:14 -0400 | [diff] [blame] | 20 | |
| 21 | An address can have a 'display_name', a 'username', and a 'domain'. In |
| 22 | addition to specifying the username and domain separately, they may be |
| 23 | specified together by using the addr_spec keyword *instead of* the |
| 24 | username and domain keywords. If an addr_spec string is specified it |
| 25 | must be properly quoted according to RFC 5322 rules; an error will be |
| 26 | raised if it is not. |
| 27 | |
| 28 | An Address object has display_name, username, domain, and addr_spec |
| 29 | attributes, all of which are read-only. The addr_spec and the string |
| 30 | value of the object are both quoted according to RFC5322 rules, but |
| 31 | without any Content Transfer Encoding. |
| 32 | |
| 33 | """ |
| 34 | # This clause with its potential 'raise' may only happen when an |
| 35 | # application program creates an Address object using an addr_spec |
| 36 | # keyword. The email library code itself must always supply username |
| 37 | # and domain. |
| 38 | if addr_spec is not None: |
| 39 | if username or domain: |
| 40 | raise TypeError("addrspec specified when username and/or " |
| 41 | "domain also specified") |
| 42 | a_s, rest = parser.get_addr_spec(addr_spec) |
| 43 | if rest: |
| 44 | raise ValueError("Invalid addr_spec; only '{}' " |
| 45 | "could be parsed from '{}'".format( |
| 46 | a_s, addr_spec)) |
| 47 | if a_s.all_defects: |
| 48 | raise a_s.all_defects[0] |
| 49 | username = a_s.local_part |
| 50 | domain = a_s.domain |
| 51 | self._display_name = display_name |
| 52 | self._username = username |
| 53 | self._domain = domain |
| 54 | |
| 55 | @property |
| 56 | def display_name(self): |
| 57 | return self._display_name |
| 58 | |
| 59 | @property |
| 60 | def username(self): |
| 61 | return self._username |
| 62 | |
| 63 | @property |
| 64 | def domain(self): |
| 65 | return self._domain |
| 66 | |
| 67 | @property |
| 68 | def addr_spec(self): |
| 69 | """The addr_spec (username@domain) portion of the address, quoted |
| 70 | according to RFC 5322 rules, but with no Content Transfer Encoding. |
| 71 | """ |
| 72 | nameset = set(self.username) |
| 73 | if len(nameset) > len(nameset-parser.DOT_ATOM_ENDS): |
| 74 | lp = parser.quote_string(self.username) |
| 75 | else: |
| 76 | lp = self.username |
| 77 | if self.domain: |
| 78 | return lp + '@' + self.domain |
| 79 | if not lp: |
| 80 | return '<>' |
| 81 | return lp |
| 82 | |
| 83 | def __repr__(self): |
Serhiy Storchaka | 465e60e | 2014-07-25 23:36:00 +0300 | [diff] [blame] | 84 | return "{}(display_name={!r}, username={!r}, domain={!r})".format( |
| 85 | self.__class__.__name__, |
R David Murray | 0b6f6c8 | 2012-05-25 18:42:14 -0400 | [diff] [blame] | 86 | self.display_name, self.username, self.domain) |
| 87 | |
| 88 | def __str__(self): |
| 89 | nameset = set(self.display_name) |
| 90 | if len(nameset) > len(nameset-parser.SPECIALS): |
| 91 | disp = parser.quote_string(self.display_name) |
| 92 | else: |
| 93 | disp = self.display_name |
| 94 | if disp: |
| 95 | addr_spec = '' if self.addr_spec=='<>' else self.addr_spec |
| 96 | return "{} <{}>".format(disp, addr_spec) |
| 97 | return self.addr_spec |
| 98 | |
| 99 | def __eq__(self, other): |
| 100 | if type(other) != type(self): |
| 101 | return False |
| 102 | return (self.display_name == other.display_name and |
| 103 | self.username == other.username and |
| 104 | self.domain == other.domain) |
| 105 | |
| 106 | |
| 107 | class Group: |
| 108 | |
| 109 | def __init__(self, display_name=None, addresses=None): |
| 110 | """Create an object representing an address group. |
| 111 | |
Serhiy Storchaka | 6a7b3a7 | 2016-04-17 08:32:47 +0300 | [diff] [blame] | 112 | An address group consists of a display_name followed by colon and a |
R David Murray | 0b6f6c8 | 2012-05-25 18:42:14 -0400 | [diff] [blame] | 113 | list of addresses (see Address) terminated by a semi-colon. The Group |
| 114 | is created by specifying a display_name and a possibly empty list of |
| 115 | Address objects. A Group can also be used to represent a single |
| 116 | address that is not in a group, which is convenient when manipulating |
| 117 | lists that are a combination of Groups and individual Addresses. In |
| 118 | this case the display_name should be set to None. In particular, the |
| 119 | string representation of a Group whose display_name is None is the same |
| 120 | as the Address object, if there is one and only one Address object in |
| 121 | the addresses list. |
| 122 | |
| 123 | """ |
| 124 | self._display_name = display_name |
| 125 | self._addresses = tuple(addresses) if addresses else tuple() |
| 126 | |
| 127 | @property |
| 128 | def display_name(self): |
| 129 | return self._display_name |
| 130 | |
| 131 | @property |
| 132 | def addresses(self): |
| 133 | return self._addresses |
| 134 | |
| 135 | def __repr__(self): |
Serhiy Storchaka | 465e60e | 2014-07-25 23:36:00 +0300 | [diff] [blame] | 136 | return "{}(display_name={!r}, addresses={!r}".format( |
| 137 | self.__class__.__name__, |
R David Murray | 0b6f6c8 | 2012-05-25 18:42:14 -0400 | [diff] [blame] | 138 | self.display_name, self.addresses) |
| 139 | |
| 140 | def __str__(self): |
| 141 | if self.display_name is None and len(self.addresses)==1: |
| 142 | return str(self.addresses[0]) |
| 143 | disp = self.display_name |
| 144 | if disp is not None: |
| 145 | nameset = set(disp) |
| 146 | if len(nameset) > len(nameset-parser.SPECIALS): |
| 147 | disp = parser.quote_string(disp) |
| 148 | adrstr = ", ".join(str(x) for x in self.addresses) |
| 149 | adrstr = ' ' + adrstr if adrstr else adrstr |
| 150 | return "{}:{};".format(disp, adrstr) |
| 151 | |
| 152 | def __eq__(self, other): |
| 153 | if type(other) != type(self): |
| 154 | return False |
| 155 | return (self.display_name == other.display_name and |
| 156 | self.addresses == other.addresses) |
| 157 | |
| 158 | |
| 159 | # Header Classes # |
| 160 | |
| 161 | class BaseHeader(str): |
| 162 | |
| 163 | """Base class for message headers. |
| 164 | |
| 165 | Implements generic behavior and provides tools for subclasses. |
| 166 | |
| 167 | A subclass must define a classmethod named 'parse' that takes an unfolded |
| 168 | value string and a dictionary as its arguments. The dictionary will |
| 169 | contain one key, 'defects', initialized to an empty list. After the call |
| 170 | the dictionary must contain two additional keys: parse_tree, set to the |
| 171 | parse tree obtained from parsing the header, and 'decoded', set to the |
| 172 | string value of the idealized representation of the data from the value. |
| 173 | (That is, encoded words are decoded, and values that have canonical |
| 174 | representations are so represented.) |
| 175 | |
| 176 | The defects key is intended to collect parsing defects, which the message |
| 177 | parser will subsequently dispose of as appropriate. The parser should not, |
| 178 | insofar as practical, raise any errors. Defects should be added to the |
| 179 | list instead. The standard header parsers register defects for RFC |
| 180 | compliance issues, for obsolete RFC syntax, and for unrecoverable parsing |
| 181 | errors. |
| 182 | |
| 183 | The parse method may add additional keys to the dictionary. In this case |
| 184 | the subclass must define an 'init' method, which will be passed the |
| 185 | dictionary as its keyword arguments. The method should use (usually by |
| 186 | setting them as the value of similarly named attributes) and remove all the |
| 187 | extra keys added by its parse method, and then use super to call its parent |
| 188 | class with the remaining arguments and keywords. |
| 189 | |
| 190 | The subclass should also make sure that a 'max_count' attribute is defined |
| 191 | that is either None or 1. XXX: need to better define this API. |
| 192 | |
| 193 | """ |
| 194 | |
| 195 | def __new__(cls, name, value): |
| 196 | kwds = {'defects': []} |
| 197 | cls.parse(value, kwds) |
| 198 | if utils._has_surrogates(kwds['decoded']): |
| 199 | kwds['decoded'] = utils._sanitize(kwds['decoded']) |
| 200 | self = str.__new__(cls, kwds['decoded']) |
| 201 | del kwds['decoded'] |
| 202 | self.init(name, **kwds) |
| 203 | return self |
| 204 | |
| 205 | def init(self, name, *, parse_tree, defects): |
| 206 | self._name = name |
| 207 | self._parse_tree = parse_tree |
| 208 | self._defects = defects |
| 209 | |
| 210 | @property |
| 211 | def name(self): |
| 212 | return self._name |
| 213 | |
| 214 | @property |
| 215 | def defects(self): |
| 216 | return tuple(self._defects) |
| 217 | |
| 218 | def __reduce__(self): |
| 219 | return ( |
| 220 | _reconstruct_header, |
| 221 | ( |
| 222 | self.__class__.__name__, |
| 223 | self.__class__.__bases__, |
| 224 | str(self), |
| 225 | ), |
| 226 | self.__dict__) |
| 227 | |
| 228 | @classmethod |
| 229 | def _reconstruct(cls, value): |
| 230 | return str.__new__(cls, value) |
| 231 | |
| 232 | def fold(self, *, policy): |
| 233 | """Fold header according to policy. |
| 234 | |
| 235 | The parsed representation of the header is folded according to |
| 236 | RFC5322 rules, as modified by the policy. If the parse tree |
| 237 | contains surrogateescaped bytes, the bytes are CTE encoded using |
| 238 | the charset 'unknown-8bit". |
| 239 | |
| 240 | Any non-ASCII characters in the parse tree are CTE encoded using |
| 241 | charset utf-8. XXX: make this a policy setting. |
| 242 | |
| 243 | The returned value is an ASCII-only string possibly containing linesep |
| 244 | characters, and ending with a linesep character. The string includes |
| 245 | the header name and the ': ' separator. |
| 246 | |
| 247 | """ |
| 248 | # At some point we need to only put fws here if it was in the source. |
| 249 | header = parser.Header([ |
| 250 | parser.HeaderLabel([ |
| 251 | parser.ValueTerminal(self.name, 'header-name'), |
| 252 | parser.ValueTerminal(':', 'header-sep')]), |
| 253 | parser.CFWSList([parser.WhiteSpaceTerminal(' ', 'fws')]), |
| 254 | self._parse_tree]) |
| 255 | return header.fold(policy=policy) |
| 256 | |
| 257 | |
| 258 | def _reconstruct_header(cls_name, bases, value): |
| 259 | return type(cls_name, bases, {})._reconstruct(value) |
| 260 | |
| 261 | |
| 262 | class UnstructuredHeader: |
| 263 | |
| 264 | max_count = None |
| 265 | value_parser = staticmethod(parser.get_unstructured) |
| 266 | |
| 267 | @classmethod |
| 268 | def parse(cls, value, kwds): |
| 269 | kwds['parse_tree'] = cls.value_parser(value) |
| 270 | kwds['decoded'] = str(kwds['parse_tree']) |
| 271 | |
| 272 | |
| 273 | class UniqueUnstructuredHeader(UnstructuredHeader): |
| 274 | |
| 275 | max_count = 1 |
| 276 | |
| 277 | |
| 278 | class DateHeader: |
| 279 | |
| 280 | """Header whose value consists of a single timestamp. |
| 281 | |
| 282 | Provides an additional attribute, datetime, which is either an aware |
| 283 | datetime using a timezone, or a naive datetime if the timezone |
| 284 | in the input string is -0000. Also accepts a datetime as input. |
| 285 | The 'value' attribute is the normalized form of the timestamp, |
| 286 | which means it is the output of format_datetime on the datetime. |
| 287 | """ |
| 288 | |
| 289 | max_count = None |
| 290 | |
| 291 | # This is used only for folding, not for creating 'decoded'. |
| 292 | value_parser = staticmethod(parser.get_unstructured) |
| 293 | |
| 294 | @classmethod |
| 295 | def parse(cls, value, kwds): |
| 296 | if not value: |
| 297 | kwds['defects'].append(errors.HeaderMissingRequiredValue()) |
| 298 | kwds['datetime'] = None |
| 299 | kwds['decoded'] = '' |
| 300 | kwds['parse_tree'] = parser.TokenList() |
| 301 | return |
| 302 | if isinstance(value, str): |
| 303 | value = utils.parsedate_to_datetime(value) |
| 304 | kwds['datetime'] = value |
| 305 | kwds['decoded'] = utils.format_datetime(kwds['datetime']) |
| 306 | kwds['parse_tree'] = cls.value_parser(kwds['decoded']) |
| 307 | |
| 308 | def init(self, *args, **kw): |
| 309 | self._datetime = kw.pop('datetime') |
| 310 | super().init(*args, **kw) |
| 311 | |
| 312 | @property |
| 313 | def datetime(self): |
| 314 | return self._datetime |
| 315 | |
| 316 | |
| 317 | class UniqueDateHeader(DateHeader): |
| 318 | |
| 319 | max_count = 1 |
| 320 | |
| 321 | |
| 322 | class AddressHeader: |
| 323 | |
| 324 | max_count = None |
| 325 | |
| 326 | @staticmethod |
| 327 | def value_parser(value): |
| 328 | address_list, value = parser.get_address_list(value) |
| 329 | assert not value, 'this should not happen' |
| 330 | return address_list |
| 331 | |
| 332 | @classmethod |
| 333 | def parse(cls, value, kwds): |
| 334 | if isinstance(value, str): |
| 335 | # We are translating here from the RFC language (address/mailbox) |
| 336 | # to our API language (group/address). |
| 337 | kwds['parse_tree'] = address_list = cls.value_parser(value) |
| 338 | groups = [] |
| 339 | for addr in address_list.addresses: |
| 340 | groups.append(Group(addr.display_name, |
| 341 | [Address(mb.display_name or '', |
| 342 | mb.local_part or '', |
| 343 | mb.domain or '') |
| 344 | for mb in addr.all_mailboxes])) |
| 345 | defects = list(address_list.all_defects) |
| 346 | else: |
| 347 | # Assume it is Address/Group stuff |
| 348 | if not hasattr(value, '__iter__'): |
| 349 | value = [value] |
| 350 | groups = [Group(None, [item]) if not hasattr(item, 'addresses') |
| 351 | else item |
| 352 | for item in value] |
| 353 | defects = [] |
| 354 | kwds['groups'] = groups |
| 355 | kwds['defects'] = defects |
| 356 | kwds['decoded'] = ', '.join([str(item) for item in groups]) |
| 357 | if 'parse_tree' not in kwds: |
| 358 | kwds['parse_tree'] = cls.value_parser(kwds['decoded']) |
| 359 | |
| 360 | def init(self, *args, **kw): |
| 361 | self._groups = tuple(kw.pop('groups')) |
| 362 | self._addresses = None |
| 363 | super().init(*args, **kw) |
| 364 | |
| 365 | @property |
| 366 | def groups(self): |
| 367 | return self._groups |
| 368 | |
| 369 | @property |
| 370 | def addresses(self): |
| 371 | if self._addresses is None: |
| 372 | self._addresses = tuple([address for group in self._groups |
| 373 | for address in group.addresses]) |
| 374 | return self._addresses |
| 375 | |
| 376 | |
| 377 | class UniqueAddressHeader(AddressHeader): |
| 378 | |
| 379 | max_count = 1 |
| 380 | |
| 381 | |
| 382 | class SingleAddressHeader(AddressHeader): |
| 383 | |
| 384 | @property |
| 385 | def address(self): |
| 386 | if len(self.addresses)!=1: |
| 387 | raise ValueError(("value of single address header {} is not " |
| 388 | "a single address").format(self.name)) |
| 389 | return self.addresses[0] |
| 390 | |
| 391 | |
| 392 | class UniqueSingleAddressHeader(SingleAddressHeader): |
| 393 | |
| 394 | max_count = 1 |
| 395 | |
| 396 | |
R David Murray | 97f43c0 | 2012-06-24 05:03:27 -0400 | [diff] [blame] | 397 | class MIMEVersionHeader: |
| 398 | |
| 399 | max_count = 1 |
| 400 | |
| 401 | value_parser = staticmethod(parser.parse_mime_version) |
| 402 | |
| 403 | @classmethod |
| 404 | def parse(cls, value, kwds): |
| 405 | kwds['parse_tree'] = parse_tree = cls.value_parser(value) |
| 406 | kwds['decoded'] = str(parse_tree) |
| 407 | kwds['defects'].extend(parse_tree.all_defects) |
| 408 | kwds['major'] = None if parse_tree.minor is None else parse_tree.major |
| 409 | kwds['minor'] = parse_tree.minor |
| 410 | if parse_tree.minor is not None: |
| 411 | kwds['version'] = '{}.{}'.format(kwds['major'], kwds['minor']) |
| 412 | else: |
| 413 | kwds['version'] = None |
| 414 | |
| 415 | def init(self, *args, **kw): |
| 416 | self._version = kw.pop('version') |
| 417 | self._major = kw.pop('major') |
| 418 | self._minor = kw.pop('minor') |
| 419 | super().init(*args, **kw) |
| 420 | |
| 421 | @property |
| 422 | def major(self): |
| 423 | return self._major |
| 424 | |
| 425 | @property |
| 426 | def minor(self): |
| 427 | return self._minor |
| 428 | |
| 429 | @property |
| 430 | def version(self): |
| 431 | return self._version |
| 432 | |
| 433 | |
| 434 | class ParameterizedMIMEHeader: |
| 435 | |
| 436 | # Mixin that handles the params dict. Must be subclassed and |
| 437 | # a property value_parser for the specific header provided. |
| 438 | |
| 439 | max_count = 1 |
| 440 | |
| 441 | @classmethod |
| 442 | def parse(cls, value, kwds): |
| 443 | kwds['parse_tree'] = parse_tree = cls.value_parser(value) |
| 444 | kwds['decoded'] = str(parse_tree) |
| 445 | kwds['defects'].extend(parse_tree.all_defects) |
| 446 | if parse_tree.params is None: |
| 447 | kwds['params'] = {} |
| 448 | else: |
| 449 | # The MIME RFCs specify that parameter ordering is arbitrary. |
| 450 | kwds['params'] = {utils._sanitize(name).lower(): |
| 451 | utils._sanitize(value) |
| 452 | for name, value in parse_tree.params} |
| 453 | |
| 454 | def init(self, *args, **kw): |
| 455 | self._params = kw.pop('params') |
| 456 | super().init(*args, **kw) |
| 457 | |
| 458 | @property |
| 459 | def params(self): |
R David Murray | 685b349 | 2014-10-17 19:30:13 -0400 | [diff] [blame] | 460 | return MappingProxyType(self._params) |
R David Murray | 97f43c0 | 2012-06-24 05:03:27 -0400 | [diff] [blame] | 461 | |
| 462 | |
| 463 | class ContentTypeHeader(ParameterizedMIMEHeader): |
| 464 | |
| 465 | value_parser = staticmethod(parser.parse_content_type_header) |
| 466 | |
| 467 | def init(self, *args, **kw): |
| 468 | super().init(*args, **kw) |
| 469 | self._maintype = utils._sanitize(self._parse_tree.maintype) |
| 470 | self._subtype = utils._sanitize(self._parse_tree.subtype) |
| 471 | |
| 472 | @property |
| 473 | def maintype(self): |
| 474 | return self._maintype |
| 475 | |
| 476 | @property |
| 477 | def subtype(self): |
| 478 | return self._subtype |
| 479 | |
| 480 | @property |
| 481 | def content_type(self): |
| 482 | return self.maintype + '/' + self.subtype |
| 483 | |
| 484 | |
| 485 | class ContentDispositionHeader(ParameterizedMIMEHeader): |
| 486 | |
| 487 | value_parser = staticmethod(parser.parse_content_disposition_header) |
| 488 | |
| 489 | def init(self, *args, **kw): |
| 490 | super().init(*args, **kw) |
| 491 | cd = self._parse_tree.content_disposition |
| 492 | self._content_disposition = cd if cd is None else utils._sanitize(cd) |
| 493 | |
| 494 | @property |
| 495 | def content_disposition(self): |
| 496 | return self._content_disposition |
| 497 | |
| 498 | |
| 499 | class ContentTransferEncodingHeader: |
| 500 | |
| 501 | max_count = 1 |
| 502 | |
| 503 | value_parser = staticmethod(parser.parse_content_transfer_encoding_header) |
| 504 | |
| 505 | @classmethod |
| 506 | def parse(cls, value, kwds): |
| 507 | kwds['parse_tree'] = parse_tree = cls.value_parser(value) |
| 508 | kwds['decoded'] = str(parse_tree) |
| 509 | kwds['defects'].extend(parse_tree.all_defects) |
| 510 | |
| 511 | def init(self, *args, **kw): |
| 512 | super().init(*args, **kw) |
| 513 | self._cte = utils._sanitize(self._parse_tree.cte) |
| 514 | |
| 515 | @property |
| 516 | def cte(self): |
| 517 | return self._cte |
| 518 | |
| 519 | |
R David Murray | 0b6f6c8 | 2012-05-25 18:42:14 -0400 | [diff] [blame] | 520 | # The header factory # |
| 521 | |
| 522 | _default_header_map = { |
R David Murray | 97f43c0 | 2012-06-24 05:03:27 -0400 | [diff] [blame] | 523 | 'subject': UniqueUnstructuredHeader, |
| 524 | 'date': UniqueDateHeader, |
| 525 | 'resent-date': DateHeader, |
| 526 | 'orig-date': UniqueDateHeader, |
| 527 | 'sender': UniqueSingleAddressHeader, |
| 528 | 'resent-sender': SingleAddressHeader, |
| 529 | 'to': UniqueAddressHeader, |
| 530 | 'resent-to': AddressHeader, |
| 531 | 'cc': UniqueAddressHeader, |
| 532 | 'resent-cc': AddressHeader, |
| 533 | 'bcc': UniqueAddressHeader, |
| 534 | 'resent-bcc': AddressHeader, |
| 535 | 'from': UniqueAddressHeader, |
| 536 | 'resent-from': AddressHeader, |
| 537 | 'reply-to': UniqueAddressHeader, |
| 538 | 'mime-version': MIMEVersionHeader, |
| 539 | 'content-type': ContentTypeHeader, |
| 540 | 'content-disposition': ContentDispositionHeader, |
| 541 | 'content-transfer-encoding': ContentTransferEncodingHeader, |
R David Murray | 0b6f6c8 | 2012-05-25 18:42:14 -0400 | [diff] [blame] | 542 | } |
| 543 | |
| 544 | class HeaderRegistry: |
| 545 | |
| 546 | """A header_factory and header registry.""" |
| 547 | |
| 548 | def __init__(self, base_class=BaseHeader, default_class=UnstructuredHeader, |
| 549 | use_default_map=True): |
| 550 | """Create a header_factory that works with the Policy API. |
| 551 | |
| 552 | base_class is the class that will be the last class in the created |
| 553 | header class's __bases__ list. default_class is the class that will be |
| 554 | used if "name" (see __call__) does not appear in the registry. |
| 555 | use_default_map controls whether or not the default mapping of names to |
| 556 | specialized classes is copied in to the registry when the factory is |
| 557 | created. The default is True. |
| 558 | |
| 559 | """ |
| 560 | self.registry = {} |
| 561 | self.base_class = base_class |
| 562 | self.default_class = default_class |
| 563 | if use_default_map: |
| 564 | self.registry.update(_default_header_map) |
| 565 | |
| 566 | def map_to_type(self, name, cls): |
| 567 | """Register cls as the specialized class for handling "name" headers. |
| 568 | |
| 569 | """ |
| 570 | self.registry[name.lower()] = cls |
| 571 | |
| 572 | def __getitem__(self, name): |
| 573 | cls = self.registry.get(name.lower(), self.default_class) |
| 574 | return type('_'+cls.__name__, (cls, self.base_class), {}) |
| 575 | |
| 576 | def __call__(self, name, value): |
| 577 | """Create a header instance for header 'name' from 'value'. |
| 578 | |
| 579 | Creates a header instance by creating a specialized class for parsing |
| 580 | and representing the specified header by combining the factory |
| 581 | base_class with a specialized class from the registry or the |
| 582 | default_class, and passing the name and value to the constructed |
| 583 | class's constructor. |
| 584 | |
| 585 | """ |
| 586 | return self[name](name, value) |