| 1 | """ codecs -- Python Codec Registry, API and helpers. |
| 2 | |
| 3 | |
| 4 | Written by Marc-Andre Lemburg (mal@lemburg.com). |
| 5 | |
| 6 | (c) Copyright CNRI, All Rights Reserved. NO WARRANTY. |
| 7 | |
| 8 | """#" |
| 9 | |
| 10 | import __builtin__, sys |
| 11 | |
| 12 | ### Registry and builtin stateless codec functions |
| 13 | |
| 14 | try: |
| 15 | from _codecs import * |
| 16 | except ImportError, why: |
| 17 | raise SystemError,\ |
| 18 | 'Failed to load the builtin codecs: %s' % why |
| 19 | |
| 20 | __all__ = ["register", "lookup", "open", "EncodedFile", "BOM", "BOM_BE", |
| 21 | "BOM_LE", "BOM32_BE", "BOM32_LE", "BOM64_BE", "BOM64_LE", |
| 22 | "BOM_UTF8", "BOM_UTF16", "BOM_UTF16_LE", "BOM_UTF16_BE", |
| 23 | "BOM_UTF32", "BOM_UTF32_LE", "BOM_UTF32_BE", |
| 24 | "strict_errors", "ignore_errors", "replace_errors", |
| 25 | "xmlcharrefreplace_errors", |
| 26 | "register_error", "lookup_error"] |
| 27 | |
| 28 | ### Constants |
| 29 | |
| 30 | # |
| 31 | # Byte Order Mark (BOM = ZERO WIDTH NO-BREAK SPACE = U+FEFF) |
| 32 | # and its possible byte string values |
| 33 | # for UTF8/UTF16/UTF32 output and little/big endian machines |
| 34 | # |
| 35 | |
| 36 | # UTF-8 |
| 37 | BOM_UTF8 = '\xef\xbb\xbf' |
| 38 | |
| 39 | # UTF-16, little endian |
| 40 | BOM_LE = BOM_UTF16_LE = '\xff\xfe' |
| 41 | |
| 42 | # UTF-16, big endian |
| 43 | BOM_BE = BOM_UTF16_BE = '\xfe\xff' |
| 44 | |
| 45 | # UTF-32, little endian |
| 46 | BOM_UTF32_LE = '\xff\xfe\x00\x00' |
| 47 | |
| 48 | # UTF-32, big endian |
| 49 | BOM_UTF32_BE = '\x00\x00\xfe\xff' |
| 50 | |
| 51 | if sys.byteorder == 'little': |
| 52 | |
| 53 | # UTF-16, native endianness |
| 54 | BOM = BOM_UTF16 = BOM_UTF16_LE |
| 55 | |
| 56 | # UTF-32, native endianness |
| 57 | BOM_UTF32 = BOM_UTF32_LE |
| 58 | |
| 59 | else: |
| 60 | |
| 61 | # UTF-16, native endianness |
| 62 | BOM = BOM_UTF16 = BOM_UTF16_BE |
| 63 | |
| 64 | # UTF-32, native endianness |
| 65 | BOM_UTF32 = BOM_UTF32_BE |
| 66 | |
| 67 | # Old broken names (don't use in new code) |
| 68 | BOM32_LE = BOM_UTF16_LE |
| 69 | BOM32_BE = BOM_UTF16_BE |
| 70 | BOM64_LE = BOM_UTF32_LE |
| 71 | BOM64_BE = BOM_UTF32_BE |
| 72 | |
| 73 | |
| 74 | ### Codec base classes (defining the API) |
| 75 | |
| 76 | class Codec: |
| 77 | |
| 78 | """ Defines the interface for stateless encoders/decoders. |
| 79 | |
| 80 | The .encode()/.decode() methods may use different error |
| 81 | handling schemes by providing the errors argument. These |
| 82 | string values are predefined: |
| 83 | |
| 84 | 'strict' - raise a ValueError error (or a subclass) |
| 85 | 'ignore' - ignore the character and continue with the next |
| 86 | 'replace' - replace with a suitable replacement character; |
| 87 | Python will use the official U+FFFD REPLACEMENT |
| 88 | CHARACTER for the builtin Unicode codecs on |
| 89 | decoding and '?' on encoding. |
| 90 | 'xmlcharrefreplace' - Replace with the appropriate XML |
| 91 | character reference (only for encoding). |
| 92 | 'backslashreplace' - Replace with backslashed escape sequences |
| 93 | (only for encoding). |
| 94 | |
| 95 | The set of allowed values can be extended via register_error. |
| 96 | |
| 97 | """ |
| 98 | def encode(self, input, errors='strict'): |
| 99 | |
| 100 | """ Encodes the object input and returns a tuple (output |
| 101 | object, length consumed). |
| 102 | |
| 103 | errors defines the error handling to apply. It defaults to |
| 104 | 'strict' handling. |
| 105 | |
| 106 | The method may not store state in the Codec instance. Use |
| 107 | StreamCodec for codecs which have to keep state in order to |
| 108 | make encoding/decoding efficient. |
| 109 | |
| 110 | The encoder must be able to handle zero length input and |
| 111 | return an empty object of the output object type in this |
| 112 | situation. |
| 113 | |
| 114 | """ |
| 115 | raise NotImplementedError |
| 116 | |
| 117 | def decode(self, input, errors='strict'): |
| 118 | |
| 119 | """ Decodes the object input and returns a tuple (output |
| 120 | object, length consumed). |
| 121 | |
| 122 | input must be an object which provides the bf_getreadbuf |
| 123 | buffer slot. Python strings, buffer objects and memory |
| 124 | mapped files are examples of objects providing this slot. |
| 125 | |
| 126 | errors defines the error handling to apply. It defaults to |
| 127 | 'strict' handling. |
| 128 | |
| 129 | The method may not store state in the Codec instance. Use |
| 130 | StreamCodec for codecs which have to keep state in order to |
| 131 | make encoding/decoding efficient. |
| 132 | |
| 133 | The decoder must be able to handle zero length input and |
| 134 | return an empty object of the output object type in this |
| 135 | situation. |
| 136 | |
| 137 | """ |
| 138 | raise NotImplementedError |
| 139 | |
| 140 | # |
| 141 | # The StreamWriter and StreamReader class provide generic working |
| 142 | # interfaces which can be used to implement new encoding submodules |
| 143 | # very easily. See encodings/utf_8.py for an example on how this is |
| 144 | # done. |
| 145 | # |
| 146 | |
| 147 | class StreamWriter(Codec): |
| 148 | |
| 149 | def __init__(self, stream, errors='strict'): |
| 150 | |
| 151 | """ Creates a StreamWriter instance. |
| 152 | |
| 153 | stream must be a file-like object open for writing |
| 154 | (binary) data. |
| 155 | |
| 156 | The StreamWriter may use different error handling |
| 157 | schemes by providing the errors keyword argument. These |
| 158 | parameters are predefined: |
| 159 | |
| 160 | 'strict' - raise a ValueError (or a subclass) |
| 161 | 'ignore' - ignore the character and continue with the next |
| 162 | 'replace'- replace with a suitable replacement character |
| 163 | 'xmlcharrefreplace' - Replace with the appropriate XML |
| 164 | character reference. |
| 165 | 'backslashreplace' - Replace with backslashed escape |
| 166 | sequences (only for encoding). |
| 167 | |
| 168 | The set of allowed parameter values can be extended via |
| 169 | register_error. |
| 170 | """ |
| 171 | self.stream = stream |
| 172 | self.errors = errors |
| 173 | |
| 174 | def write(self, object): |
| 175 | |
| 176 | """ Writes the object's contents encoded to self.stream. |
| 177 | """ |
| 178 | data, consumed = self.encode(object, self.errors) |
| 179 | self.stream.write(data) |
| 180 | |
| 181 | def writelines(self, list): |
| 182 | |
| 183 | """ Writes the concatenated list of strings to the stream |
| 184 | using .write(). |
| 185 | """ |
| 186 | self.write(''.join(list)) |
| 187 | |
| 188 | def reset(self): |
| 189 | |
| 190 | """ Flushes and resets the codec buffers used for keeping state. |
| 191 | |
| 192 | Calling this method should ensure that the data on the |
| 193 | output is put into a clean state, that allows appending |
| 194 | of new fresh data without having to rescan the whole |
| 195 | stream to recover state. |
| 196 | |
| 197 | """ |
| 198 | pass |
| 199 | |
| 200 | def __getattr__(self, name, |
| 201 | getattr=getattr): |
| 202 | |
| 203 | """ Inherit all other methods from the underlying stream. |
| 204 | """ |
| 205 | return getattr(self.stream, name) |
| 206 | |
| 207 | ### |
| 208 | |
| 209 | class StreamReader(Codec): |
| 210 | |
| 211 | def __init__(self, stream, errors='strict'): |
| 212 | |
| 213 | """ Creates a StreamReader instance. |
| 214 | |
| 215 | stream must be a file-like object open for reading |
| 216 | (binary) data. |
| 217 | |
| 218 | The StreamReader may use different error handling |
| 219 | schemes by providing the errors keyword argument. These |
| 220 | parameters are predefined: |
| 221 | |
| 222 | 'strict' - raise a ValueError (or a subclass) |
| 223 | 'ignore' - ignore the character and continue with the next |
| 224 | 'replace'- replace with a suitable replacement character; |
| 225 | |
| 226 | The set of allowed parameter values can be extended via |
| 227 | register_error. |
| 228 | """ |
| 229 | self.stream = stream |
| 230 | self.errors = errors |
| 231 | self.bytebuffer = "" |
| 232 | # For str->str decoding this will stay a str |
| 233 | # For str->unicode decoding the first read will promote it to unicode |
| 234 | self.charbuffer = "" |
| 235 | self.linebuffer = None |
| 236 | |
| 237 | def decode(self, input, errors='strict'): |
| 238 | raise NotImplementedError |
| 239 | |
| 240 | def read(self, size=-1, chars=-1, firstline=False): |
| 241 | |
| 242 | """ Decodes data from the stream self.stream and returns the |
| 243 | resulting object. |
| 244 | |
| 245 | chars indicates the number of characters to read from the |
| 246 | stream. read() will never return more than chars |
| 247 | characters, but it might return less, if there are not enough |
| 248 | characters available. |
| 249 | |
| 250 | size indicates the approximate maximum number of bytes to |
| 251 | read from the stream for decoding purposes. The decoder |
| 252 | can modify this setting as appropriate. The default value |
| 253 | -1 indicates to read and decode as much as possible. size |
| 254 | is intended to prevent having to decode huge files in one |
| 255 | step. |
| 256 | |
| 257 | If firstline is true, and a UnicodeDecodeError happens |
| 258 | after the first line terminator in the input only the first line |
| 259 | will be returned, the rest of the input will be kept until the |
| 260 | next call to read(). |
| 261 | |
| 262 | The method should use a greedy read strategy meaning that |
| 263 | it should read as much data as is allowed within the |
| 264 | definition of the encoding and the given size, e.g. if |
| 265 | optional encoding endings or state markers are available |
| 266 | on the stream, these should be read too. |
| 267 | """ |
| 268 | # If we have lines cached, first merge them back into characters |
| 269 | if self.linebuffer: |
| 270 | self.charbuffer = "".join(self.linebuffer) |
| 271 | self.linebuffer = None |
| 272 | |
| 273 | # read until we get the required number of characters (if available) |
| 274 | while True: |
| 275 | # can the request can be satisfied from the character buffer? |
| 276 | if chars < 0: |
| 277 | if self.charbuffer: |
| 278 | break |
| 279 | else: |
| 280 | if len(self.charbuffer) >= chars: |
| 281 | break |
| 282 | # we need more data |
| 283 | if size < 0: |
| 284 | newdata = self.stream.read() |
| 285 | else: |
| 286 | newdata = self.stream.read(size) |
| 287 | # decode bytes (those remaining from the last call included) |
| 288 | data = self.bytebuffer + newdata |
| 289 | try: |
| 290 | newchars, decodedbytes = self.decode(data, self.errors) |
| 291 | except UnicodeDecodeError, exc: |
| 292 | if firstline: |
| 293 | newchars, decodedbytes = self.decode(data[:exc.start], self.errors) |
| 294 | lines = newchars.splitlines(True) |
| 295 | if len(lines)<=1: |
| 296 | raise |
| 297 | else: |
| 298 | raise |
| 299 | # keep undecoded bytes until the next call |
| 300 | self.bytebuffer = data[decodedbytes:] |
| 301 | # put new characters in the character buffer |
| 302 | self.charbuffer += newchars |
| 303 | # there was no data available |
| 304 | if not newdata: |
| 305 | break |
| 306 | if chars < 0: |
| 307 | # Return everything we've got |
| 308 | result = self.charbuffer |
| 309 | self.charbuffer = "" |
| 310 | else: |
| 311 | # Return the first chars characters |
| 312 | result = self.charbuffer[:chars] |
| 313 | self.charbuffer = self.charbuffer[chars:] |
| 314 | return result |
| 315 | |
| 316 | def readline(self, size=None, keepends=True): |
| 317 | |
| 318 | """ Read one line from the input stream and return the |
| 319 | decoded data. |
| 320 | |
| 321 | size, if given, is passed as size argument to the |
| 322 | read() method. |
| 323 | |
| 324 | """ |
| 325 | # If we have lines cached from an earlier read, return |
| 326 | # them unconditionally |
| 327 | if self.linebuffer: |
| 328 | line = self.linebuffer[0] |
| 329 | del self.linebuffer[0] |
| 330 | if len(self.linebuffer) == 1: |
| 331 | # revert to charbuffer mode; we might need more data |
| 332 | # next time |
| 333 | self.charbuffer = self.linebuffer[0] |
| 334 | self.linebuffer = None |
| 335 | if not keepends: |
| 336 | line = line.splitlines(False)[0] |
| 337 | return line |
| 338 | |
| 339 | readsize = size or 72 |
| 340 | line = "" |
| 341 | # If size is given, we call read() only once |
| 342 | while True: |
| 343 | data = self.read(readsize, firstline=True) |
| 344 | if data: |
| 345 | # If we're at a "\r" read one extra character (which might |
| 346 | # be a "\n") to get a proper line ending. If the stream is |
| 347 | # temporarily exhausted we return the wrong line ending. |
| 348 | if data.endswith("\r"): |
| 349 | data += self.read(size=1, chars=1) |
| 350 | |
| 351 | line += data |
| 352 | lines = line.splitlines(True) |
| 353 | if lines: |
| 354 | if len(lines) > 1: |
| 355 | # More than one line result; the first line is a full line |
| 356 | # to return |
| 357 | line = lines[0] |
| 358 | del lines[0] |
| 359 | if len(lines) > 1: |
| 360 | # cache the remaining lines |
| 361 | lines[-1] += self.charbuffer |
| 362 | self.linebuffer = lines |
| 363 | self.charbuffer = None |
| 364 | else: |
| 365 | # only one remaining line, put it back into charbuffer |
| 366 | self.charbuffer = lines[0] + self.charbuffer |
| 367 | if not keepends: |
| 368 | line = line.splitlines(False)[0] |
| 369 | break |
| 370 | line0withend = lines[0] |
| 371 | line0withoutend = lines[0].splitlines(False)[0] |
| 372 | if line0withend != line0withoutend: # We really have a line end |
| 373 | # Put the rest back together and keep it until the next call |
| 374 | self.charbuffer = "".join(lines[1:]) + self.charbuffer |
| 375 | if keepends: |
| 376 | line = line0withend |
| 377 | else: |
| 378 | line = line0withoutend |
| 379 | break |
| 380 | # we didn't get anything or this was our only try |
| 381 | if not data or size is not None: |
| 382 | if line and not keepends: |
| 383 | line = line.splitlines(False)[0] |
| 384 | break |
| 385 | if readsize<8000: |
| 386 | readsize *= 2 |
| 387 | return line |
| 388 | |
| 389 | def readlines(self, sizehint=None, keepends=True): |
| 390 | |
| 391 | """ Read all lines available on the input stream |
| 392 | and return them as list of lines. |
| 393 | |
| 394 | Line breaks are implemented using the codec's decoder |
| 395 | method and are included in the list entries. |
| 396 | |
| 397 | sizehint, if given, is ignored since there is no efficient |
| 398 | way to finding the true end-of-line. |
| 399 | |
| 400 | """ |
| 401 | data = self.read() |
| 402 | return data.splitlines(keepends) |
| 403 | |
| 404 | def reset(self): |
| 405 | |
| 406 | """ Resets the codec buffers used for keeping state. |
| 407 | |
| 408 | Note that no stream repositioning should take place. |
| 409 | This method is primarily intended to be able to recover |
| 410 | from decoding errors. |
| 411 | |
| 412 | """ |
| 413 | self.bytebuffer = "" |
| 414 | self.charbuffer = u"" |
| 415 | self.linebuffer = None |
| 416 | |
| 417 | def seek(self, offset, whence=0): |
| 418 | """ Set the input stream's current position. |
| 419 | |
| 420 | Resets the codec buffers used for keeping state. |
| 421 | """ |
| 422 | self.reset() |
| 423 | self.stream.seek(offset, whence) |
| 424 | |
| 425 | def next(self): |
| 426 | |
| 427 | """ Return the next decoded line from the input stream.""" |
| 428 | line = self.readline() |
| 429 | if line: |
| 430 | return line |
| 431 | raise StopIteration |
| 432 | |
| 433 | def __iter__(self): |
| 434 | return self |
| 435 | |
| 436 | def __getattr__(self, name, |
| 437 | getattr=getattr): |
| 438 | |
| 439 | """ Inherit all other methods from the underlying stream. |
| 440 | """ |
| 441 | return getattr(self.stream, name) |
| 442 | |
| 443 | ### |
| 444 | |
| 445 | class StreamReaderWriter: |
| 446 | |
| 447 | """ StreamReaderWriter instances allow wrapping streams which |
| 448 | work in both read and write modes. |
| 449 | |
| 450 | The design is such that one can use the factory functions |
| 451 | returned by the codec.lookup() function to construct the |
| 452 | instance. |
| 453 | |
| 454 | """ |
| 455 | # Optional attributes set by the file wrappers below |
| 456 | encoding = 'unknown' |
| 457 | |
| 458 | def __init__(self, stream, Reader, Writer, errors='strict'): |
| 459 | |
| 460 | """ Creates a StreamReaderWriter instance. |
| 461 | |
| 462 | stream must be a Stream-like object. |
| 463 | |
| 464 | Reader, Writer must be factory functions or classes |
| 465 | providing the StreamReader, StreamWriter interface resp. |
| 466 | |
| 467 | Error handling is done in the same way as defined for the |
| 468 | StreamWriter/Readers. |
| 469 | |
| 470 | """ |
| 471 | self.stream = stream |
| 472 | self.reader = Reader(stream, errors) |
| 473 | self.writer = Writer(stream, errors) |
| 474 | self.errors = errors |
| 475 | |
| 476 | def read(self, size=-1): |
| 477 | |
| 478 | return self.reader.read(size) |
| 479 | |
| 480 | def readline(self, size=None): |
| 481 | |
| 482 | return self.reader.readline(size) |
| 483 | |
| 484 | def readlines(self, sizehint=None): |
| 485 | |
| 486 | return self.reader.readlines(sizehint) |
| 487 | |
| 488 | def next(self): |
| 489 | |
| 490 | """ Return the next decoded line from the input stream.""" |
| 491 | return self.reader.next() |
| 492 | |
| 493 | def __iter__(self): |
| 494 | return self |
| 495 | |
| 496 | def write(self, data): |
| 497 | |
| 498 | return self.writer.write(data) |
| 499 | |
| 500 | def writelines(self, list): |
| 501 | |
| 502 | return self.writer.writelines(list) |
| 503 | |
| 504 | def reset(self): |
| 505 | |
| 506 | self.reader.reset() |
| 507 | self.writer.reset() |
| 508 | |
| 509 | def __getattr__(self, name, |
| 510 | getattr=getattr): |
| 511 | |
| 512 | """ Inherit all other methods from the underlying stream. |
| 513 | """ |
| 514 | return getattr(self.stream, name) |
| 515 | |
| 516 | ### |
| 517 | |
| 518 | class StreamRecoder: |
| 519 | |
| 520 | """ StreamRecoder instances provide a frontend - backend |
| 521 | view of encoding data. |
| 522 | |
| 523 | They use the complete set of APIs returned by the |
| 524 | codecs.lookup() function to implement their task. |
| 525 | |
| 526 | Data written to the stream is first decoded into an |
| 527 | intermediate format (which is dependent on the given codec |
| 528 | combination) and then written to the stream using an instance |
| 529 | of the provided Writer class. |
| 530 | |
| 531 | In the other direction, data is read from the stream using a |
| 532 | Reader instance and then return encoded data to the caller. |
| 533 | |
| 534 | """ |
| 535 | # Optional attributes set by the file wrappers below |
| 536 | data_encoding = 'unknown' |
| 537 | file_encoding = 'unknown' |
| 538 | |
| 539 | def __init__(self, stream, encode, decode, Reader, Writer, |
| 540 | errors='strict'): |
| 541 | |
| 542 | """ Creates a StreamRecoder instance which implements a two-way |
| 543 | conversion: encode and decode work on the frontend (the |
| 544 | input to .read() and output of .write()) while |
| 545 | Reader and Writer work on the backend (reading and |
| 546 | writing to the stream). |
| 547 | |
| 548 | You can use these objects to do transparent direct |
| 549 | recodings from e.g. latin-1 to utf-8 and back. |
| 550 | |
| 551 | stream must be a file-like object. |
| 552 | |
| 553 | encode, decode must adhere to the Codec interface, Reader, |
| 554 | Writer must be factory functions or classes providing the |
| 555 | StreamReader, StreamWriter interface resp. |
| 556 | |
| 557 | encode and decode are needed for the frontend translation, |
| 558 | Reader and Writer for the backend translation. Unicode is |
| 559 | used as intermediate encoding. |
| 560 | |
| 561 | Error handling is done in the same way as defined for the |
| 562 | StreamWriter/Readers. |
| 563 | |
| 564 | """ |
| 565 | self.stream = stream |
| 566 | self.encode = encode |
| 567 | self.decode = decode |
| 568 | self.reader = Reader(stream, errors) |
| 569 | self.writer = Writer(stream, errors) |
| 570 | self.errors = errors |
| 571 | |
| 572 | def read(self, size=-1): |
| 573 | |
| 574 | data = self.reader.read(size) |
| 575 | data, bytesencoded = self.encode(data, self.errors) |
| 576 | return data |
| 577 | |
| 578 | def readline(self, size=None): |
| 579 | |
| 580 | if size is None: |
| 581 | data = self.reader.readline() |
| 582 | else: |
| 583 | data = self.reader.readline(size) |
| 584 | data, bytesencoded = self.encode(data, self.errors) |
| 585 | return data |
| 586 | |
| 587 | def readlines(self, sizehint=None): |
| 588 | |
| 589 | data = self.reader.read() |
| 590 | data, bytesencoded = self.encode(data, self.errors) |
| 591 | return data.splitlines(1) |
| 592 | |
| 593 | def next(self): |
| 594 | |
| 595 | """ Return the next decoded line from the input stream.""" |
| 596 | data = self.reader.next() |
| 597 | data, bytesencoded = self.encode(data, self.errors) |
| 598 | return data |
| 599 | |
| 600 | def __iter__(self): |
| 601 | return self |
| 602 | |
| 603 | def write(self, data): |
| 604 | |
| 605 | data, bytesdecoded = self.decode(data, self.errors) |
| 606 | return self.writer.write(data) |
| 607 | |
| 608 | def writelines(self, list): |
| 609 | |
| 610 | data = ''.join(list) |
| 611 | data, bytesdecoded = self.decode(data, self.errors) |
| 612 | return self.writer.write(data) |
| 613 | |
| 614 | def reset(self): |
| 615 | |
| 616 | self.reader.reset() |
| 617 | self.writer.reset() |
| 618 | |
| 619 | def __getattr__(self, name, |
| 620 | getattr=getattr): |
| 621 | |
| 622 | """ Inherit all other methods from the underlying stream. |
| 623 | """ |
| 624 | return getattr(self.stream, name) |
| 625 | |
| 626 | ### Shortcuts |
| 627 | |
| 628 | def open(filename, mode='rb', encoding=None, errors='strict', buffering=1): |
| 629 | |
| 630 | """ Open an encoded file using the given mode and return |
| 631 | a wrapped version providing transparent encoding/decoding. |
| 632 | |
| 633 | Note: The wrapped version will only accept the object format |
| 634 | defined by the codecs, i.e. Unicode objects for most builtin |
| 635 | codecs. Output is also codec dependent and will usually by |
| 636 | Unicode as well. |
| 637 | |
| 638 | Files are always opened in binary mode, even if no binary mode |
| 639 | was specified. This is done to avoid data loss due to encodings |
| 640 | using 8-bit values. The default file mode is 'rb' meaning to |
| 641 | open the file in binary read mode. |
| 642 | |
| 643 | encoding specifies the encoding which is to be used for the |
| 644 | file. |
| 645 | |
| 646 | errors may be given to define the error handling. It defaults |
| 647 | to 'strict' which causes ValueErrors to be raised in case an |
| 648 | encoding error occurs. |
| 649 | |
| 650 | buffering has the same meaning as for the builtin open() API. |
| 651 | It defaults to line buffered. |
| 652 | |
| 653 | The returned wrapped file object provides an extra attribute |
| 654 | .encoding which allows querying the used encoding. This |
| 655 | attribute is only available if an encoding was specified as |
| 656 | parameter. |
| 657 | |
| 658 | """ |
| 659 | if encoding is not None and \ |
| 660 | 'b' not in mode: |
| 661 | # Force opening of the file in binary mode |
| 662 | mode = mode + 'b' |
| 663 | file = __builtin__.open(filename, mode, buffering) |
| 664 | if encoding is None: |
| 665 | return file |
| 666 | (e, d, sr, sw) = lookup(encoding) |
| 667 | srw = StreamReaderWriter(file, sr, sw, errors) |
| 668 | # Add attributes to simplify introspection |
| 669 | srw.encoding = encoding |
| 670 | return srw |
| 671 | |
| 672 | def EncodedFile(file, data_encoding, file_encoding=None, errors='strict'): |
| 673 | |
| 674 | """ Return a wrapped version of file which provides transparent |
| 675 | encoding translation. |
| 676 | |
| 677 | Strings written to the wrapped file are interpreted according |
| 678 | to the given data_encoding and then written to the original |
| 679 | file as string using file_encoding. The intermediate encoding |
| 680 | will usually be Unicode but depends on the specified codecs. |
| 681 | |
| 682 | Strings are read from the file using file_encoding and then |
| 683 | passed back to the caller as string using data_encoding. |
| 684 | |
| 685 | If file_encoding is not given, it defaults to data_encoding. |
| 686 | |
| 687 | errors may be given to define the error handling. It defaults |
| 688 | to 'strict' which causes ValueErrors to be raised in case an |
| 689 | encoding error occurs. |
| 690 | |
| 691 | The returned wrapped file object provides two extra attributes |
| 692 | .data_encoding and .file_encoding which reflect the given |
| 693 | parameters of the same name. The attributes can be used for |
| 694 | introspection by Python programs. |
| 695 | |
| 696 | """ |
| 697 | if file_encoding is None: |
| 698 | file_encoding = data_encoding |
| 699 | encode, decode = lookup(data_encoding)[:2] |
| 700 | Reader, Writer = lookup(file_encoding)[2:] |
| 701 | sr = StreamRecoder(file, |
| 702 | encode, decode, Reader, Writer, |
| 703 | errors) |
| 704 | # Add attributes to simplify introspection |
| 705 | sr.data_encoding = data_encoding |
| 706 | sr.file_encoding = file_encoding |
| 707 | return sr |
| 708 | |
| 709 | ### Helpers for codec lookup |
| 710 | |
| 711 | def getencoder(encoding): |
| 712 | |
| 713 | """ Lookup up the codec for the given encoding and return |
| 714 | its encoder function. |
| 715 | |
| 716 | Raises a LookupError in case the encoding cannot be found. |
| 717 | |
| 718 | """ |
| 719 | return lookup(encoding)[0] |
| 720 | |
| 721 | def getdecoder(encoding): |
| 722 | |
| 723 | """ Lookup up the codec for the given encoding and return |
| 724 | its decoder function. |
| 725 | |
| 726 | Raises a LookupError in case the encoding cannot be found. |
| 727 | |
| 728 | """ |
| 729 | return lookup(encoding)[1] |
| 730 | |
| 731 | def getreader(encoding): |
| 732 | |
| 733 | """ Lookup up the codec for the given encoding and return |
| 734 | its StreamReader class or factory function. |
| 735 | |
| 736 | Raises a LookupError in case the encoding cannot be found. |
| 737 | |
| 738 | """ |
| 739 | return lookup(encoding)[2] |
| 740 | |
| 741 | def getwriter(encoding): |
| 742 | |
| 743 | """ Lookup up the codec for the given encoding and return |
| 744 | its StreamWriter class or factory function. |
| 745 | |
| 746 | Raises a LookupError in case the encoding cannot be found. |
| 747 | |
| 748 | """ |
| 749 | return lookup(encoding)[3] |
| 750 | |
| 751 | ### Helpers for charmap-based codecs |
| 752 | |
| 753 | def make_identity_dict(rng): |
| 754 | |
| 755 | """ make_identity_dict(rng) -> dict |
| 756 | |
| 757 | Return a dictionary where elements of the rng sequence are |
| 758 | mapped to themselves. |
| 759 | |
| 760 | """ |
| 761 | res = {} |
| 762 | for i in rng: |
| 763 | res[i]=i |
| 764 | return res |
| 765 | |
| 766 | def make_encoding_map(decoding_map): |
| 767 | |
| 768 | """ Creates an encoding map from a decoding map. |
| 769 | |
| 770 | If a target mapping in the decoding map occurs multiple |
| 771 | times, then that target is mapped to None (undefined mapping), |
| 772 | causing an exception when encountered by the charmap codec |
| 773 | during translation. |
| 774 | |
| 775 | One example where this happens is cp875.py which decodes |
| 776 | multiple character to \u001a. |
| 777 | |
| 778 | """ |
| 779 | m = {} |
| 780 | for k,v in decoding_map.items(): |
| 781 | if not v in m: |
| 782 | m[v] = k |
| 783 | else: |
| 784 | m[v] = None |
| 785 | return m |
| 786 | |
| 787 | ### error handlers |
| 788 | |
| 789 | try: |
| 790 | strict_errors = lookup_error("strict") |
| 791 | ignore_errors = lookup_error("ignore") |
| 792 | replace_errors = lookup_error("replace") |
| 793 | xmlcharrefreplace_errors = lookup_error("xmlcharrefreplace") |
| 794 | backslashreplace_errors = lookup_error("backslashreplace") |
| 795 | except LookupError: |
| 796 | # In --disable-unicode builds, these error handler are missing |
| 797 | strict_errors = None |
| 798 | ignore_errors = None |
| 799 | replace_errors = None |
| 800 | xmlcharrefreplace_errors = None |
| 801 | backslashreplace_errors = None |
| 802 | |
| 803 | # Tell modulefinder that using codecs probably needs the encodings |
| 804 | # package |
| 805 | _false = 0 |
| 806 | if _false: |
| 807 | import encodings |
| 808 | |
| 809 | ### Tests |
| 810 | |
| 811 | if __name__ == '__main__': |
| 812 | |
| 813 | # Make stdout translate Latin-1 output into UTF-8 output |
| 814 | sys.stdout = EncodedFile(sys.stdout, 'latin-1', 'utf-8') |
| 815 | |
| 816 | # Have stdin translate Latin-1 input into UTF-8 input |
| 817 | sys.stdin = EncodedFile(sys.stdin, 'utf-8', 'latin-1') |