source file: /System/Library/Frameworks/Python.framework/Versions/2.3/lib/python2.3/email/Charset.py
file stats: 111 lines, 43 executed: 38.7% covered
1. # Copyright (C) 2001,2002 Python Software Foundation 2. # Author: che@debian.org (Ben Gertzfield), barry@zope.com (Barry Warsaw) 3. 4. from types import UnicodeType 5. from email.Encoders import encode_7or8bit 6. import email.base64MIME 7. import email.quopriMIME 8. 9. def _isunicode(s): 10. return isinstance(s, UnicodeType) 11. 12. # Python 2.2.1 and beyond has these symbols 13. try: 14. True, False 15. except NameError: 16. True = 1 17. False = 0 18. 19. 20. 21. # Flags for types of header encodings 22. QP = 1 # Quoted-Printable 23. BASE64 = 2 # Base64 24. SHORTEST = 3 # the shorter of QP and base64, but only for headers 25. 26. # In "=?charset?q?hello_world?=", the =?, ?q?, and ?= add up to 7 27. MISC_LEN = 7 28. 29. DEFAULT_CHARSET = 'us-ascii' 30. 31. 32. 33. # Defaults 34. CHARSETS = { 35. # input header enc body enc output conv 36. 'iso-8859-1': (QP, QP, None), 37. 'iso-8859-2': (QP, QP, None), 38. 'iso-8859-3': (QP, QP, None), 39. 'iso-8859-4': (QP, QP, None), 40. # iso-8859-5 is Cyrillic, and not especially used 41. # iso-8859-6 is Arabic, also not particularly used 42. # iso-8859-7 is Greek, QP will not make it readable 43. # iso-8859-8 is Hebrew, QP will not make it readable 44. 'iso-8859-9': (QP, QP, None), 45. 'iso-8859-10': (QP, QP, None), 46. # iso-8859-11 is Thai, QP will not make it readable 47. 'iso-8859-13': (QP, QP, None), 48. 'iso-8859-14': (QP, QP, None), 49. 'iso-8859-15': (QP, QP, None), 50. 'windows-1252':(QP, QP, None), 51. 'viscii': (QP, QP, None), 52. 'us-ascii': (None, None, None), 53. 'big5': (BASE64, BASE64, None), 54. 'gb2312': (BASE64, BASE64, None), 55. 'euc-jp': (BASE64, None, 'iso-2022-jp'), 56. 'shift_jis': (BASE64, None, 'iso-2022-jp'), 57. 'iso-2022-jp': (BASE64, None, None), 58. 'koi8-r': (BASE64, BASE64, None), 59. 'utf-8': (SHORTEST, BASE64, 'utf-8'), 60. # We're making this one up to represent raw unencoded 8-bit 61. '8bit': (None, BASE64, 'utf-8'), 62. } 63. 64. # Aliases for other commonly-used names for character sets. Map 65. # them to the real ones used in email. 66. ALIASES = { 67. 'latin_1': 'iso-8859-1', 68. 'latin-1': 'iso-8859-1', 69. 'latin_2': 'iso-8859-2', 70. 'latin-2': 'iso-8859-2', 71. 'latin_3': 'iso-8859-3', 72. 'latin-3': 'iso-8859-3', 73. 'latin_4': 'iso-8859-4', 74. 'latin-4': 'iso-8859-4', 75. 'latin_5': 'iso-8859-9', 76. 'latin-5': 'iso-8859-9', 77. 'latin_6': 'iso-8859-10', 78. 'latin-6': 'iso-8859-10', 79. 'latin_7': 'iso-8859-13', 80. 'latin-7': 'iso-8859-13', 81. 'latin_8': 'iso-8859-14', 82. 'latin-8': 'iso-8859-14', 83. 'latin_9': 'iso-8859-15', 84. 'latin-9': 'iso-8859-15', 85. 'cp949': 'ks_c_5601-1987', 86. 'euc_jp': 'euc-jp', 87. 'euc_kr': 'euc-kr', 88. 'ascii': 'us-ascii', 89. } 90. 91. # Map charsets to their Unicode codec strings. Note that Python doesn't come 92. # with any Asian codecs by default. Here's where to get them: 93. # 94. # Japanese -- http://www.asahi-net.or.jp/~rd6t-kjym/python 95. # Korean -- http://sf.net/projects/koco 96. # Chinese -- http://sf.net/projects/python-codecs 97. # 98. # Note that these codecs have their own lifecycle and may be in varying states 99. # of stability and useability. 100. 101. CODEC_MAP = { 102. 'euc-jp': 'japanese.euc-jp', 103. 'iso-2022-jp': 'japanese.iso-2022-jp', 104. 'shift_jis': 'japanese.shift_jis', 105. 'euc-kr': 'korean.euc-kr', 106. 'ks_c_5601-1987': 'korean.cp949', 107. 'iso-2022-kr': 'korean.iso-2022-kr', 108. 'johab': 'korean.johab', 109. 'gb2132': 'eucgb2312_cn', 110. 'big5': 'big5_tw', 111. 'utf-8': 'utf-8', 112. # Hack: We don't want *any* conversion for stuff marked us-ascii, as all 113. # sorts of garbage might be sent to us in the guise of 7-bit us-ascii. 114. # Let that stuff pass through without conversion to/from Unicode. 115. 'us-ascii': None, 116. } 117. 118. 119. 120. # Convenience functions for extending the above mappings 121. def add_charset(charset, header_enc=None, body_enc=None, output_charset=None): 122. """Add character set properties to the global registry. 123. 124. charset is the input character set, and must be the canonical name of a 125. character set. 126. 127. Optional header_enc and body_enc is either Charset.QP for 128. quoted-printable, Charset.BASE64 for base64 encoding, Charset.SHORTEST for 129. the shortest of qp or base64 encoding, or None for no encoding. SHORTEST 130. is only valid for header_enc. It describes how message headers and 131. message bodies in the input charset are to be encoded. Default is no 132. encoding. 133. 134. Optional output_charset is the character set that the output should be 135. in. Conversions will proceed from input charset, to Unicode, to the 136. output charset when the method Charset.convert() is called. The default 137. is to output in the same character set as the input. 138. 139. Both input_charset and output_charset must have Unicode codec entries in 140. the module's charset-to-codec mapping; use add_codec(charset, codecname) 141. to add codecs the module does not know about. See the codecs module's 142. documentation for more information. 143. """ 144. if body_enc == SHORTEST: 145. raise ValueError, 'SHORTEST not allowed for body_enc' 146. CHARSETS[charset] = (header_enc, body_enc, output_charset) 147. 148. 149. def add_alias(alias, canonical): 150. """Add a character set alias. 151. 152. alias is the alias name, e.g. latin-1 153. canonical is the character set's canonical name, e.g. iso-8859-1 154. """ 155. ALIASES[alias] = canonical 156. 157. 158. def add_codec(charset, codecname): 159. """Add a codec that map characters in the given charset to/from Unicode. 160. 161. charset is the canonical name of a character set. codecname is the name 162. of a Python codec, as appropriate for the second argument to the unicode() 163. built-in, or to the encode() method of a Unicode string. 164. """ 165. CODEC_MAP[charset] = codecname 166. 167. 168. 169. class Charset: 170. """Map character sets to their email properties. 171. 172. This class provides information about the requirements imposed on email 173. for a specific character set. It also provides convenience routines for 174. converting between character sets, given the availability of the 175. applicable codecs. Given a character set, it will do its best to provide 176. information on how to use that character set in an email in an 177. RFC-compliant way. 178. 179. Certain character sets must be encoded with quoted-printable or base64 180. when used in email headers or bodies. Certain character sets must be 181. converted outright, and are not allowed in email. Instances of this 182. module expose the following information about a character set: 183. 184. input_charset: The initial character set specified. Common aliases 185. are converted to their `official' email names (e.g. latin_1 186. is converted to iso-8859-1). Defaults to 7-bit us-ascii. 187. 188. header_encoding: If the character set must be encoded before it can be 189. used in an email header, this attribute will be set to 190. Charset.QP (for quoted-printable), Charset.BASE64 (for 191. base64 encoding), or Charset.SHORTEST for the shortest of 192. QP or BASE64 encoding. Otherwise, it will be None. 193. 194. body_encoding: Same as header_encoding, but describes the encoding for the 195. mail message's body, which indeed may be different than the 196. header encoding. Charset.SHORTEST is not allowed for 197. body_encoding. 198. 199. output_charset: Some character sets must be converted before the can be 200. used in email headers or bodies. If the input_charset is 201. one of them, this attribute will contain the name of the 202. charset output will be converted to. Otherwise, it will 203. be None. 204. 205. input_codec: The name of the Python codec used to convert the 206. input_charset to Unicode. If no conversion codec is 207. necessary, this attribute will be None. 208. 209. output_codec: The name of the Python codec used to convert Unicode 210. to the output_charset. If no conversion codec is necessary, 211. this attribute will have the same value as the input_codec. 212. """ 213. def __init__(self, input_charset=DEFAULT_CHARSET): 214. # RFC 2046, $4.1.2 says charsets are not case sensitive 215. input_charset = input_charset.lower() 216. # Set the input charset after filtering through the aliases 217. self.input_charset = ALIASES.get(input_charset, input_charset) 218. # We can try to guess which encoding and conversion to use by the 219. # charset_map dictionary. Try that first, but let the user override 220. # it. 221. henc, benc, conv = CHARSETS.get(self.input_charset, 222. (SHORTEST, BASE64, None)) 223. # Set the attributes, allowing the arguments to override the default. 224. self.header_encoding = henc 225. self.body_encoding = benc 226. self.output_charset = ALIASES.get(conv, conv) 227. # Now set the codecs. If one isn't defined for input_charset, 228. # guess and try a Unicode codec with the same name as input_codec. 229. self.input_codec = CODEC_MAP.get(self.input_charset, 230. self.input_charset) 231. self.output_codec = CODEC_MAP.get(self.output_charset, 232. self.input_codec) 233. 234. def __str__(self): 235. return self.input_charset.lower() 236. 237. __repr__ = __str__ 238. 239. def __eq__(self, other): 240. return str(self) == str(other).lower() 241. 242. def __ne__(self, other): 243. return not self.__eq__(other) 244. 245. def get_body_encoding(self): 246. """Return the content-transfer-encoding used for body encoding. 247. 248. This is either the string `quoted-printable' or `base64' depending on 249. the encoding used, or it is a function in which case you should call 250. the function with a single argument, the Message object being 251. encoded. The function should then set the Content-Transfer-Encoding 252. header itself to whatever is appropriate. 253. 254. Returns "quoted-printable" if self.body_encoding is QP. 255. Returns "base64" if self.body_encoding is BASE64. 256. Returns "7bit" otherwise. 257. """ 258. assert self.body_encoding <> SHORTEST 259. if self.body_encoding == QP: 260. return 'quoted-printable' 261. elif self.body_encoding == BASE64: 262. return 'base64' 263. else: 264. return encode_7or8bit 265. 266. def convert(self, s): 267. """Convert a string from the input_codec to the output_codec.""" 268. if self.input_codec <> self.output_codec: 269. return unicode(s, self.input_codec).encode(self.output_codec) 270. else: 271. return s 272. 273. def to_splittable(self, s): 274. """Convert a possibly multibyte string to a safely splittable format. 275. 276. Uses the input_codec to try and convert the string to Unicode, so it 277. can be safely split on character boundaries (even for multibyte 278. characters). 279. 280. Returns the string as-is if it isn't known how to convert it to 281. Unicode with the input_charset. 282. 283. Characters that could not be converted to Unicode will be replaced 284. with the Unicode replacement character U+FFFD. 285. """ 286. if _isunicode(s) or self.input_codec is None: 287. return s 288. try: 289. return unicode(s, self.input_codec, 'replace') 290. except LookupError: 291. # Input codec not installed on system, so return the original 292. # string unchanged. 293. return s 294. 295. def from_splittable(self, ustr, to_output=True): 296. """Convert a splittable string back into an encoded string. 297. 298. Uses the proper codec to try and convert the string from Unicode back 299. into an encoded format. Return the string as-is if it is not Unicode, 300. or if it could not be converted from Unicode. 301. 302. Characters that could not be converted from Unicode will be replaced 303. with an appropriate character (usually '?'). 304. 305. If to_output is True (the default), uses output_codec to convert to an 306. encoded format. If to_output is False, uses input_codec. 307. """ 308. if to_output: 309. codec = self.output_codec 310. else: 311. codec = self.input_codec 312. if not _isunicode(ustr) or codec is None: 313. return ustr 314. try: 315. return ustr.encode(codec, 'replace') 316. except LookupError: 317. # Output codec not installed 318. return ustr 319. 320. def get_output_charset(self): 321. """Return the output character set. 322. 323. This is self.output_charset if that is not None, otherwise it is 324. self.input_charset. 325. """ 326. return self.output_charset or self.input_charset 327. 328. def encoded_header_len(self, s): 329. """Return the length of the encoded header string.""" 330. cset = self.get_output_charset() 331. # The len(s) of a 7bit encoding is len(s) 332. if self.header_encoding == BASE64: 333. return email.base64MIME.base64_len(s) + len(cset) + MISC_LEN 334. elif self.header_encoding == QP: 335. return email.quopriMIME.header_quopri_len(s) + len(cset) + MISC_LEN 336. elif self.header_encoding == SHORTEST: 337. lenb64 = email.base64MIME.base64_len(s) 338. lenqp = email.quopriMIME.header_quopri_len(s) 339. return min(lenb64, lenqp) + len(cset) + MISC_LEN 340. else: 341. return len(s) 342. 343. def header_encode(self, s, convert=False): 344. """Header-encode a string, optionally converting it to output_charset. 345. 346. If convert is True, the string will be converted from the input 347. charset to the output charset automatically. This is not useful for 348. multibyte character sets, which have line length issues (multibyte 349. characters must be split on a character, not a byte boundary); use the 350. high-level Header class to deal with these issues. convert defaults 351. to False. 352. 353. The type of encoding (base64 or quoted-printable) will be based on 354. self.header_encoding. 355. """ 356. cset = self.get_output_charset() 357. if convert: 358. s = self.convert(s) 359. # 7bit/8bit encodings return the string unchanged (modulo conversions) 360. if self.header_encoding == BASE64: 361. return email.base64MIME.header_encode(s, cset) 362. elif self.header_encoding == QP: 363. return email.quopriMIME.header_encode(s, cset, maxlinelen=None) 364. elif self.header_encoding == SHORTEST: 365. lenb64 = email.base64MIME.base64_len(s) 366. lenqp = email.quopriMIME.header_quopri_len(s) 367. if lenb64 < lenqp: 368. return email.base64MIME.header_encode(s, cset) 369. else: 370. return email.quopriMIME.header_encode(s, cset, maxlinelen=None) 371. else: 372. return s 373. 374. def body_encode(self, s, convert=True): 375. """Body-encode a string and convert it to output_charset. 376. 377. If convert is True (the default), the string will be converted from 378. the input charset to output charset automatically. Unlike 379. header_encode(), there are no issues with byte boundaries and 380. multibyte charsets in email bodies, so this is usually pretty safe. 381. 382. The type of encoding (base64 or quoted-printable) will be based on 383. self.body_encoding. 384. """ 385. if convert: 386. s = self.convert(s) 387. # 7bit/8bit encodings return the string unchanged (module conversions) 388. if self.body_encoding is BASE64: 389. return email.base64MIME.body_encode(s) 390. elif self.body_encoding is QP: 391. return email.quopriMIME.body_encode(s) 392. else: 393. return s