Guido van Rossum | 0612d84 | 2000-03-10 23:20:43 +0000 | [diff] [blame] | 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 struct,types,__builtin__ |
| 11 | |
| 12 | ### Registry and builtin stateless codec functions |
| 13 | |
Guido van Rossum | b95de4f | 2000-03-31 17:25:23 +0000 | [diff] [blame] | 14 | try: |
| 15 | from _codecs import * |
| 16 | except ImportError,why: |
| 17 | raise SystemError,\ |
| 18 | 'Failed to load the builtin codecs: %s' % why |
Guido van Rossum | 0612d84 | 2000-03-10 23:20:43 +0000 | [diff] [blame] | 19 | |
Skip Montanaro | e99d5ea | 2001-01-20 19:54:20 +0000 | [diff] [blame] | 20 | __all__ = ["register","lookup","open","EncodedFile","BOM","BOM_BE", |
| 21 | "BOM_LE","BOM32_BE","BOM32_LE","BOM64_BE","BOM64_LE"] |
| 22 | |
Guido van Rossum | 0612d84 | 2000-03-10 23:20:43 +0000 | [diff] [blame] | 23 | ### Constants |
| 24 | |
| 25 | # |
| 26 | # Byte Order Mark (BOM) and its possible values (BOM_BE, BOM_LE) |
| 27 | # |
| 28 | BOM = struct.pack('=H',0xFEFF) |
| 29 | # |
| 30 | BOM_BE = BOM32_BE = '\376\377' |
Tim Peters | 88869f9 | 2001-01-14 23:36:06 +0000 | [diff] [blame] | 31 | # corresponds to Unicode U+FEFF in UTF-16 on big endian |
| 32 | # platforms == ZERO WIDTH NO-BREAK SPACE |
Guido van Rossum | 1c89b0e | 2000-04-11 15:41:38 +0000 | [diff] [blame] | 33 | BOM_LE = BOM32_LE = '\377\376' |
Tim Peters | 88869f9 | 2001-01-14 23:36:06 +0000 | [diff] [blame] | 34 | # corresponds to Unicode U+FFFE in UTF-16 on little endian |
| 35 | # platforms == defined as being an illegal Unicode character |
Guido van Rossum | 0612d84 | 2000-03-10 23:20:43 +0000 | [diff] [blame] | 36 | |
| 37 | # |
| 38 | # 64-bit Byte Order Marks |
| 39 | # |
| 40 | BOM64_BE = '\000\000\376\377' |
Tim Peters | 88869f9 | 2001-01-14 23:36:06 +0000 | [diff] [blame] | 41 | # corresponds to Unicode U+0000FEFF in UCS-4 |
Guido van Rossum | 0612d84 | 2000-03-10 23:20:43 +0000 | [diff] [blame] | 42 | BOM64_LE = '\377\376\000\000' |
Tim Peters | 88869f9 | 2001-01-14 23:36:06 +0000 | [diff] [blame] | 43 | # corresponds to Unicode U+0000FFFE in UCS-4 |
Guido van Rossum | 0612d84 | 2000-03-10 23:20:43 +0000 | [diff] [blame] | 44 | |
| 45 | |
| 46 | ### Codec base classes (defining the API) |
| 47 | |
| 48 | class Codec: |
| 49 | |
| 50 | """ Defines the interface for stateless encoders/decoders. |
| 51 | |
| 52 | The .encode()/.decode() methods may implement different error |
| 53 | handling schemes by providing the errors argument. These |
| 54 | string values are defined: |
| 55 | |
Guido van Rossum | d8855fd | 2000-03-24 22:14:19 +0000 | [diff] [blame] | 56 | 'strict' - raise a ValueError error (or a subclass) |
Guido van Rossum | 0612d84 | 2000-03-10 23:20:43 +0000 | [diff] [blame] | 57 | 'ignore' - ignore the character and continue with the next |
| 58 | 'replace' - replace with a suitable replacement character; |
| 59 | Python will use the official U+FFFD REPLACEMENT |
| 60 | CHARACTER for the builtin Unicode codecs. |
| 61 | |
| 62 | """ |
| 63 | def encode(self,input,errors='strict'): |
Guido van Rossum | 1c89b0e | 2000-04-11 15:41:38 +0000 | [diff] [blame] | 64 | |
Fred Drake | 3e74c0d | 2000-03-17 15:40:35 +0000 | [diff] [blame] | 65 | """ Encodes the object input and returns a tuple (output |
Guido van Rossum | 0612d84 | 2000-03-10 23:20:43 +0000 | [diff] [blame] | 66 | object, length consumed). |
| 67 | |
| 68 | errors defines the error handling to apply. It defaults to |
| 69 | 'strict' handling. |
| 70 | |
| 71 | The method may not store state in the Codec instance. Use |
| 72 | StreamCodec for codecs which have to keep state in order to |
| 73 | make encoding/decoding efficient. |
| 74 | |
| 75 | The encoder must be able to handle zero length input and |
| 76 | return an empty object of the output object type in this |
| 77 | situation. |
| 78 | |
| 79 | """ |
| 80 | raise NotImplementedError |
| 81 | |
| 82 | def decode(self,input,errors='strict'): |
| 83 | |
| 84 | """ Decodes the object input and returns a tuple (output |
| 85 | object, length consumed). |
| 86 | |
| 87 | input must be an object which provides the bf_getreadbuf |
| 88 | buffer slot. Python strings, buffer objects and memory |
| 89 | mapped files are examples of objects providing this slot. |
Guido van Rossum | 1c89b0e | 2000-04-11 15:41:38 +0000 | [diff] [blame] | 90 | |
Guido van Rossum | 0612d84 | 2000-03-10 23:20:43 +0000 | [diff] [blame] | 91 | errors defines the error handling to apply. It defaults to |
| 92 | 'strict' handling. |
| 93 | |
| 94 | The method may not store state in the Codec instance. Use |
| 95 | StreamCodec for codecs which have to keep state in order to |
| 96 | make encoding/decoding efficient. |
| 97 | |
| 98 | The decoder must be able to handle zero length input and |
| 99 | return an empty object of the output object type in this |
| 100 | situation. |
| 101 | |
Guido van Rossum | 1c89b0e | 2000-04-11 15:41:38 +0000 | [diff] [blame] | 102 | """ |
Guido van Rossum | 0612d84 | 2000-03-10 23:20:43 +0000 | [diff] [blame] | 103 | raise NotImplementedError |
| 104 | |
| 105 | # |
| 106 | # The StreamWriter and StreamReader class provide generic working |
| 107 | # interfaces which can be used to implement new encodings submodules |
| 108 | # very easily. See encodings/utf_8.py for an example on how this is |
| 109 | # done. |
Guido van Rossum | 1c89b0e | 2000-04-11 15:41:38 +0000 | [diff] [blame] | 110 | # |
Guido van Rossum | 0612d84 | 2000-03-10 23:20:43 +0000 | [diff] [blame] | 111 | |
| 112 | class StreamWriter(Codec): |
| 113 | |
| 114 | def __init__(self,stream,errors='strict'): |
| 115 | |
| 116 | """ Creates a StreamWriter instance. |
| 117 | |
| 118 | stream must be a file-like object open for writing |
| 119 | (binary) data. |
| 120 | |
| 121 | The StreamWriter may implement different error handling |
| 122 | schemes by providing the errors keyword argument. These |
| 123 | parameters are defined: |
| 124 | |
| 125 | 'strict' - raise a ValueError (or a subclass) |
| 126 | 'ignore' - ignore the character and continue with the next |
| 127 | 'replace'- replace with a suitable replacement character |
| 128 | |
| 129 | """ |
| 130 | self.stream = stream |
| 131 | self.errors = errors |
| 132 | |
Guido van Rossum | a327713 | 2000-04-11 15:37:43 +0000 | [diff] [blame] | 133 | def write(self, object): |
Guido van Rossum | 0612d84 | 2000-03-10 23:20:43 +0000 | [diff] [blame] | 134 | |
| 135 | """ Writes the object's contents encoded to self.stream. |
| 136 | """ |
| 137 | data, consumed = self.encode(object,self.errors) |
| 138 | self.stream.write(data) |
| 139 | |
Guido van Rossum | a327713 | 2000-04-11 15:37:43 +0000 | [diff] [blame] | 140 | def writelines(self, list): |
| 141 | |
| 142 | """ Writes the concatenated list of strings to the stream |
| 143 | using .write(). |
| 144 | """ |
| 145 | self.write(''.join(list)) |
Guido van Rossum | 1c89b0e | 2000-04-11 15:41:38 +0000 | [diff] [blame] | 146 | |
Guido van Rossum | 0612d84 | 2000-03-10 23:20:43 +0000 | [diff] [blame] | 147 | def reset(self): |
| 148 | |
| 149 | """ Flushes and resets the codec buffers used for keeping state. |
| 150 | |
| 151 | Calling this method should ensure that the data on the |
| 152 | output is put into a clean state, that allows appending |
| 153 | of new fresh data without having to rescan the whole |
| 154 | stream to recover state. |
| 155 | |
| 156 | """ |
| 157 | pass |
| 158 | |
| 159 | def __getattr__(self,name, |
| 160 | |
| 161 | getattr=getattr): |
| 162 | |
| 163 | """ Inherit all other methods from the underlying stream. |
| 164 | """ |
| 165 | return getattr(self.stream,name) |
| 166 | |
| 167 | ### |
| 168 | |
| 169 | class StreamReader(Codec): |
| 170 | |
| 171 | def __init__(self,stream,errors='strict'): |
| 172 | |
| 173 | """ Creates a StreamReader instance. |
| 174 | |
| 175 | stream must be a file-like object open for reading |
| 176 | (binary) data. |
| 177 | |
| 178 | The StreamReader may implement different error handling |
| 179 | schemes by providing the errors keyword argument. These |
| 180 | parameters are defined: |
| 181 | |
| 182 | 'strict' - raise a ValueError (or a subclass) |
| 183 | 'ignore' - ignore the character and continue with the next |
| 184 | 'replace'- replace with a suitable replacement character; |
| 185 | |
| 186 | """ |
| 187 | self.stream = stream |
| 188 | self.errors = errors |
| 189 | |
Guido van Rossum | a327713 | 2000-04-11 15:37:43 +0000 | [diff] [blame] | 190 | def read(self, size=-1): |
Guido van Rossum | 0612d84 | 2000-03-10 23:20:43 +0000 | [diff] [blame] | 191 | |
| 192 | """ Decodes data from the stream self.stream and returns the |
| 193 | resulting object. |
| 194 | |
| 195 | size indicates the approximate maximum number of bytes to |
| 196 | read from the stream for decoding purposes. The decoder |
| 197 | can modify this setting as appropriate. The default value |
| 198 | -1 indicates to read and decode as much as possible. size |
| 199 | is intended to prevent having to decode huge files in one |
| 200 | step. |
| 201 | |
| 202 | The method should use a greedy read strategy meaning that |
| 203 | it should read as much data as is allowed within the |
| 204 | definition of the encoding and the given size, e.g. if |
| 205 | optional encoding endings or state markers are available |
| 206 | on the stream, these should be read too. |
| 207 | |
| 208 | """ |
| 209 | # Unsliced reading: |
| 210 | if size < 0: |
Andrew M. Kuchling | c6c2838 | 2000-12-10 15:12:14 +0000 | [diff] [blame] | 211 | return self.decode(self.stream.read(), self.errors)[0] |
Guido van Rossum | 1c89b0e | 2000-04-11 15:41:38 +0000 | [diff] [blame] | 212 | |
Guido van Rossum | 0612d84 | 2000-03-10 23:20:43 +0000 | [diff] [blame] | 213 | # Sliced reading: |
| 214 | read = self.stream.read |
| 215 | decode = self.decode |
| 216 | data = read(size) |
| 217 | i = 0 |
| 218 | while 1: |
| 219 | try: |
Andrew M. Kuchling | c6c2838 | 2000-12-10 15:12:14 +0000 | [diff] [blame] | 220 | object, decodedbytes = decode(data, self.errors) |
Guido van Rossum | 0612d84 | 2000-03-10 23:20:43 +0000 | [diff] [blame] | 221 | except ValueError,why: |
| 222 | # This method is slow but should work under pretty much |
| 223 | # all conditions; at most 10 tries are made |
| 224 | i = i + 1 |
| 225 | newdata = read(1) |
| 226 | if not newdata or i > 10: |
| 227 | raise |
| 228 | data = data + newdata |
| 229 | else: |
| 230 | return object |
| 231 | |
Guido van Rossum | a327713 | 2000-04-11 15:37:43 +0000 | [diff] [blame] | 232 | def readline(self, size=None): |
| 233 | |
| 234 | """ Read one line from the input stream and return the |
| 235 | decoded data. |
| 236 | |
Fred Drake | 49fd107 | 2000-04-13 14:11:21 +0000 | [diff] [blame] | 237 | Note: Unlike the .readlines() method, this method inherits |
| 238 | the line breaking knowledge from the underlying stream's |
| 239 | .readline() method -- there is currently no support for |
| 240 | line breaking using the codec decoder due to lack of line |
| 241 | buffering. Sublcasses should however, if possible, try to |
| 242 | implement this method using their own knowledge of line |
| 243 | breaking. |
Guido van Rossum | a327713 | 2000-04-11 15:37:43 +0000 | [diff] [blame] | 244 | |
| 245 | size, if given, is passed as size argument to the stream's |
| 246 | .readline() method. |
Guido van Rossum | 1c89b0e | 2000-04-11 15:41:38 +0000 | [diff] [blame] | 247 | |
Guido van Rossum | a327713 | 2000-04-11 15:37:43 +0000 | [diff] [blame] | 248 | """ |
| 249 | if size is None: |
| 250 | line = self.stream.readline() |
| 251 | else: |
| 252 | line = self.stream.readline(size) |
Andrew M. Kuchling | c6c2838 | 2000-12-10 15:12:14 +0000 | [diff] [blame] | 253 | return self.decode(line,self.errors)[0] |
Guido van Rossum | 1c89b0e | 2000-04-11 15:41:38 +0000 | [diff] [blame] | 254 | |
Guido van Rossum | a327713 | 2000-04-11 15:37:43 +0000 | [diff] [blame] | 255 | |
| 256 | def readlines(self, sizehint=0): |
| 257 | |
| 258 | """ Read all lines available on the input stream |
| 259 | and return them as list of lines. |
| 260 | |
| 261 | Line breaks are implemented using the codec's decoder |
| 262 | method and are included in the list entries. |
Guido van Rossum | 1c89b0e | 2000-04-11 15:41:38 +0000 | [diff] [blame] | 263 | |
Guido van Rossum | a327713 | 2000-04-11 15:37:43 +0000 | [diff] [blame] | 264 | sizehint, if given, is passed as size argument to the |
| 265 | stream's .read() method. |
| 266 | |
| 267 | """ |
| 268 | if sizehint is None: |
| 269 | data = self.stream.read() |
| 270 | else: |
| 271 | data = self.stream.read(sizehint) |
Andrew M. Kuchling | c6c2838 | 2000-12-10 15:12:14 +0000 | [diff] [blame] | 272 | return self.decode(data,self.errors)[0].splitlines(1) |
Guido van Rossum | 0612d84 | 2000-03-10 23:20:43 +0000 | [diff] [blame] | 273 | |
| 274 | def reset(self): |
| 275 | |
| 276 | """ Resets the codec buffers used for keeping state. |
| 277 | |
| 278 | Note that no stream repositioning should take place. |
Thomas Wouters | 7e47402 | 2000-07-16 12:04:32 +0000 | [diff] [blame] | 279 | This method is primarily intended to be able to recover |
Guido van Rossum | 0612d84 | 2000-03-10 23:20:43 +0000 | [diff] [blame] | 280 | from decoding errors. |
| 281 | |
| 282 | """ |
| 283 | pass |
| 284 | |
| 285 | def __getattr__(self,name, |
| 286 | |
| 287 | getattr=getattr): |
| 288 | |
| 289 | """ Inherit all other methods from the underlying stream. |
| 290 | """ |
| 291 | return getattr(self.stream,name) |
| 292 | |
| 293 | ### |
| 294 | |
| 295 | class StreamReaderWriter: |
| 296 | |
Fred Drake | 49fd107 | 2000-04-13 14:11:21 +0000 | [diff] [blame] | 297 | """ StreamReaderWriter instances allow wrapping streams which |
| 298 | work in both read and write modes. |
| 299 | |
| 300 | The design is such that one can use the factory functions |
Thomas Wouters | 7e47402 | 2000-07-16 12:04:32 +0000 | [diff] [blame] | 301 | returned by the codec.lookup() function to construct the |
Fred Drake | 49fd107 | 2000-04-13 14:11:21 +0000 | [diff] [blame] | 302 | instance. |
| 303 | |
| 304 | """ |
Guido van Rossum | a327713 | 2000-04-11 15:37:43 +0000 | [diff] [blame] | 305 | # Optional attributes set by the file wrappers below |
| 306 | encoding = 'unknown' |
| 307 | |
Guido van Rossum | 0612d84 | 2000-03-10 23:20:43 +0000 | [diff] [blame] | 308 | def __init__(self,stream,Reader,Writer,errors='strict'): |
| 309 | |
| 310 | """ Creates a StreamReaderWriter instance. |
| 311 | |
| 312 | stream must be a Stream-like object. |
| 313 | |
| 314 | Reader, Writer must be factory functions or classes |
| 315 | providing the StreamReader, StreamWriter interface resp. |
| 316 | |
| 317 | Error handling is done in the same way as defined for the |
| 318 | StreamWriter/Readers. |
| 319 | |
| 320 | """ |
| 321 | self.stream = stream |
| 322 | self.reader = Reader(stream, errors) |
| 323 | self.writer = Writer(stream, errors) |
| 324 | self.errors = errors |
| 325 | |
| 326 | def read(self,size=-1): |
| 327 | |
| 328 | return self.reader.read(size) |
| 329 | |
Guido van Rossum | d58c26f | 2000-05-01 16:17:32 +0000 | [diff] [blame] | 330 | def readline(self, size=None): |
Guido van Rossum | a327713 | 2000-04-11 15:37:43 +0000 | [diff] [blame] | 331 | |
| 332 | return self.reader.readline(size) |
| 333 | |
Guido van Rossum | d58c26f | 2000-05-01 16:17:32 +0000 | [diff] [blame] | 334 | def readlines(self, sizehint=None): |
Guido van Rossum | a327713 | 2000-04-11 15:37:43 +0000 | [diff] [blame] | 335 | |
| 336 | return self.reader.readlines(sizehint) |
| 337 | |
Guido van Rossum | 0612d84 | 2000-03-10 23:20:43 +0000 | [diff] [blame] | 338 | def write(self,data): |
| 339 | |
| 340 | return self.writer.write(data) |
| 341 | |
Guido van Rossum | a327713 | 2000-04-11 15:37:43 +0000 | [diff] [blame] | 342 | def writelines(self,list): |
| 343 | |
| 344 | return self.writer.writelines(list) |
| 345 | |
Guido van Rossum | 0612d84 | 2000-03-10 23:20:43 +0000 | [diff] [blame] | 346 | def reset(self): |
| 347 | |
| 348 | self.reader.reset() |
| 349 | self.writer.reset() |
| 350 | |
| 351 | def __getattr__(self,name, |
| 352 | |
| 353 | getattr=getattr): |
| 354 | |
| 355 | """ Inherit all other methods from the underlying stream. |
| 356 | """ |
| 357 | return getattr(self.stream,name) |
| 358 | |
| 359 | ### |
| 360 | |
| 361 | class StreamRecoder: |
| 362 | |
Fred Drake | 49fd107 | 2000-04-13 14:11:21 +0000 | [diff] [blame] | 363 | """ StreamRecoder instances provide a frontend - backend |
| 364 | view of encoding data. |
| 365 | |
| 366 | They use the complete set of APIs returned by the |
| 367 | codecs.lookup() function to implement their task. |
| 368 | |
| 369 | Data written to the stream is first decoded into an |
| 370 | intermediate format (which is dependent on the given codec |
| 371 | combination) and then written to the stream using an instance |
| 372 | of the provided Writer class. |
| 373 | |
| 374 | In the other direction, data is read from the stream using a |
| 375 | Reader instance and then return encoded data to the caller. |
| 376 | |
| 377 | """ |
Guido van Rossum | a327713 | 2000-04-11 15:37:43 +0000 | [diff] [blame] | 378 | # Optional attributes set by the file wrappers below |
| 379 | data_encoding = 'unknown' |
| 380 | file_encoding = 'unknown' |
| 381 | |
Guido van Rossum | 0612d84 | 2000-03-10 23:20:43 +0000 | [diff] [blame] | 382 | def __init__(self,stream,encode,decode,Reader,Writer,errors='strict'): |
| 383 | |
| 384 | """ Creates a StreamRecoder instance which implements a two-way |
| 385 | conversion: encode and decode work on the frontend (the |
Guido van Rossum | 1c89b0e | 2000-04-11 15:41:38 +0000 | [diff] [blame] | 386 | input to .read() and output of .write()) while |
Guido van Rossum | 0612d84 | 2000-03-10 23:20:43 +0000 | [diff] [blame] | 387 | Reader and Writer work on the backend (reading and |
Fred Drake | 908670c | 2000-03-17 15:42:11 +0000 | [diff] [blame] | 388 | writing to the stream). |
Guido van Rossum | 0612d84 | 2000-03-10 23:20:43 +0000 | [diff] [blame] | 389 | |
| 390 | You can use these objects to do transparent direct |
| 391 | recodings from e.g. latin-1 to utf-8 and back. |
| 392 | |
| 393 | stream must be a file-like object. |
| 394 | |
| 395 | encode, decode must adhere to the Codec interface, Reader, |
| 396 | Writer must be factory functions or classes providing the |
| 397 | StreamReader, StreamWriter interface resp. |
| 398 | |
| 399 | encode and decode are needed for the frontend translation, |
| 400 | Reader and Writer for the backend translation. Unicode is |
| 401 | used as intermediate encoding. |
| 402 | |
| 403 | Error handling is done in the same way as defined for the |
| 404 | StreamWriter/Readers. |
| 405 | |
| 406 | """ |
| 407 | self.stream = stream |
| 408 | self.encode = encode |
| 409 | self.decode = decode |
| 410 | self.reader = Reader(stream, errors) |
| 411 | self.writer = Writer(stream, errors) |
| 412 | self.errors = errors |
| 413 | |
| 414 | def read(self,size=-1): |
| 415 | |
| 416 | data = self.reader.read(size) |
| 417 | data, bytesencoded = self.encode(data, self.errors) |
| 418 | return data |
| 419 | |
Guido van Rossum | a327713 | 2000-04-11 15:37:43 +0000 | [diff] [blame] | 420 | def readline(self,size=None): |
| 421 | |
| 422 | if size is None: |
| 423 | data = self.reader.readline() |
| 424 | else: |
| 425 | data = self.reader.readline(size) |
| 426 | data, bytesencoded = self.encode(data, self.errors) |
| 427 | return data |
| 428 | |
| 429 | def readlines(self,sizehint=None): |
| 430 | |
| 431 | if sizehint is None: |
| 432 | data = self.reader.read() |
| 433 | else: |
| 434 | data = self.reader.read(sizehint) |
| 435 | data, bytesencoded = self.encode(data, self.errors) |
| 436 | return data.splitlines(1) |
| 437 | |
Guido van Rossum | 0612d84 | 2000-03-10 23:20:43 +0000 | [diff] [blame] | 438 | def write(self,data): |
| 439 | |
| 440 | data, bytesdecoded = self.decode(data, self.errors) |
| 441 | return self.writer.write(data) |
| 442 | |
Guido van Rossum | a327713 | 2000-04-11 15:37:43 +0000 | [diff] [blame] | 443 | def writelines(self,list): |
| 444 | |
| 445 | data = ''.join(list) |
| 446 | data, bytesdecoded = self.decode(data, self.errors) |
| 447 | return self.writer.write(data) |
Guido van Rossum | 0612d84 | 2000-03-10 23:20:43 +0000 | [diff] [blame] | 448 | |
| 449 | def reset(self): |
| 450 | |
| 451 | self.reader.reset() |
| 452 | self.writer.reset() |
| 453 | |
| 454 | def __getattr__(self,name, |
| 455 | |
| 456 | getattr=getattr): |
| 457 | |
| 458 | """ Inherit all other methods from the underlying stream. |
| 459 | """ |
| 460 | return getattr(self.stream,name) |
| 461 | |
| 462 | ### Shortcuts |
| 463 | |
Marc-André Lemburg | 349a3d3 | 2000-06-21 21:21:04 +0000 | [diff] [blame] | 464 | def open(filename, mode='rb', encoding=None, errors='strict', buffering=1): |
Guido van Rossum | 0612d84 | 2000-03-10 23:20:43 +0000 | [diff] [blame] | 465 | |
| 466 | """ Open an encoded file using the given mode and return |
| 467 | a wrapped version providing transparent encoding/decoding. |
| 468 | |
| 469 | Note: The wrapped version will only accept the object format |
| 470 | defined by the codecs, i.e. Unicode objects for most builtin |
| 471 | codecs. Output is also codec dependent and will usually by |
| 472 | Unicode as well. |
| 473 | |
Marc-André Lemburg | 349a3d3 | 2000-06-21 21:21:04 +0000 | [diff] [blame] | 474 | Files are always opened in binary mode, even if no binary mode |
| 475 | was specified. Thisis done to avoid data loss due to encodings |
| 476 | using 8-bit values. The default file mode is 'rb' meaning to |
| 477 | open the file in binary read mode. |
| 478 | |
Guido van Rossum | 0612d84 | 2000-03-10 23:20:43 +0000 | [diff] [blame] | 479 | encoding specifies the encoding which is to be used for the |
| 480 | the file. |
| 481 | |
| 482 | errors may be given to define the error handling. It defaults |
| 483 | to 'strict' which causes ValueErrors to be raised in case an |
| 484 | encoding error occurs. |
| 485 | |
| 486 | buffering has the same meaning as for the builtin open() API. |
| 487 | It defaults to line buffered. |
| 488 | |
Fred Drake | 49fd107 | 2000-04-13 14:11:21 +0000 | [diff] [blame] | 489 | The returned wrapped file object provides an extra attribute |
| 490 | .encoding which allows querying the used encoding. This |
| 491 | attribute is only available if an encoding was specified as |
| 492 | parameter. |
| 493 | |
Guido van Rossum | 0612d84 | 2000-03-10 23:20:43 +0000 | [diff] [blame] | 494 | """ |
| 495 | if encoding is not None and \ |
| 496 | 'b' not in mode: |
| 497 | # Force opening of the file in binary mode |
| 498 | mode = mode + 'b' |
| 499 | file = __builtin__.open(filename, mode, buffering) |
| 500 | if encoding is None: |
| 501 | return file |
| 502 | (e,d,sr,sw) = lookup(encoding) |
Guido van Rossum | a327713 | 2000-04-11 15:37:43 +0000 | [diff] [blame] | 503 | srw = StreamReaderWriter(file, sr, sw, errors) |
| 504 | # Add attributes to simplify introspection |
| 505 | srw.encoding = encoding |
| 506 | return srw |
Guido van Rossum | 0612d84 | 2000-03-10 23:20:43 +0000 | [diff] [blame] | 507 | |
Guido van Rossum | a327713 | 2000-04-11 15:37:43 +0000 | [diff] [blame] | 508 | def EncodedFile(file, data_encoding, file_encoding=None, errors='strict'): |
Guido van Rossum | 0612d84 | 2000-03-10 23:20:43 +0000 | [diff] [blame] | 509 | |
| 510 | """ Return a wrapped version of file which provides transparent |
| 511 | encoding translation. |
| 512 | |
| 513 | Strings written to the wrapped file are interpreted according |
Guido van Rossum | a327713 | 2000-04-11 15:37:43 +0000 | [diff] [blame] | 514 | to the given data_encoding and then written to the original |
| 515 | file as string using file_encoding. The intermediate encoding |
| 516 | will usually be Unicode but depends on the specified codecs. |
Guido van Rossum | 0612d84 | 2000-03-10 23:20:43 +0000 | [diff] [blame] | 517 | |
Guido van Rossum | a327713 | 2000-04-11 15:37:43 +0000 | [diff] [blame] | 518 | Strings are read from the file using file_encoding and then |
| 519 | passed back to the caller as string using data_encoding. |
| 520 | |
| 521 | If file_encoding is not given, it defaults to data_encoding. |
Guido van Rossum | 0612d84 | 2000-03-10 23:20:43 +0000 | [diff] [blame] | 522 | |
| 523 | errors may be given to define the error handling. It defaults |
| 524 | to 'strict' which causes ValueErrors to be raised in case an |
| 525 | encoding error occurs. |
| 526 | |
Fred Drake | 49fd107 | 2000-04-13 14:11:21 +0000 | [diff] [blame] | 527 | The returned wrapped file object provides two extra attributes |
| 528 | .data_encoding and .file_encoding which reflect the given |
| 529 | parameters of the same name. The attributes can be used for |
| 530 | introspection by Python programs. |
| 531 | |
Guido van Rossum | 0612d84 | 2000-03-10 23:20:43 +0000 | [diff] [blame] | 532 | """ |
Guido van Rossum | a327713 | 2000-04-11 15:37:43 +0000 | [diff] [blame] | 533 | if file_encoding is None: |
| 534 | file_encoding = data_encoding |
| 535 | encode, decode = lookup(data_encoding)[:2] |
| 536 | Reader, Writer = lookup(file_encoding)[2:] |
| 537 | sr = StreamRecoder(file, |
| 538 | encode,decode,Reader,Writer, |
| 539 | errors) |
| 540 | # Add attributes to simplify introspection |
| 541 | sr.data_encoding = data_encoding |
| 542 | sr.file_encoding = file_encoding |
| 543 | return sr |
Guido van Rossum | 0612d84 | 2000-03-10 23:20:43 +0000 | [diff] [blame] | 544 | |
Marc-André Lemburg | a866df8 | 2001-01-03 21:29:14 +0000 | [diff] [blame] | 545 | ### Helpers for charmap-based codecs |
| 546 | |
| 547 | def make_identity_dict(rng): |
| 548 | |
| 549 | """ make_identity_dict(rng) -> dict |
| 550 | |
| 551 | Return a dictionary where elements of the rng sequence are |
| 552 | mapped to themselves. |
Tim Peters | 88869f9 | 2001-01-14 23:36:06 +0000 | [diff] [blame] | 553 | |
Marc-André Lemburg | a866df8 | 2001-01-03 21:29:14 +0000 | [diff] [blame] | 554 | """ |
| 555 | res = {} |
| 556 | for i in rng: |
| 557 | res[i]=i |
| 558 | return res |
| 559 | |
Guido van Rossum | 0612d84 | 2000-03-10 23:20:43 +0000 | [diff] [blame] | 560 | ### Tests |
Guido van Rossum | 1c89b0e | 2000-04-11 15:41:38 +0000 | [diff] [blame] | 561 | |
Guido van Rossum | 0612d84 | 2000-03-10 23:20:43 +0000 | [diff] [blame] | 562 | if __name__ == '__main__': |
| 563 | |
| 564 | import sys |
Guido van Rossum | 1c89b0e | 2000-04-11 15:41:38 +0000 | [diff] [blame] | 565 | |
Guido van Rossum | a327713 | 2000-04-11 15:37:43 +0000 | [diff] [blame] | 566 | # Make stdout translate Latin-1 output into UTF-8 output |
| 567 | sys.stdout = EncodedFile(sys.stdout, 'latin-1', 'utf-8') |
Guido van Rossum | 1c89b0e | 2000-04-11 15:41:38 +0000 | [diff] [blame] | 568 | |
Guido van Rossum | a327713 | 2000-04-11 15:37:43 +0000 | [diff] [blame] | 569 | # Have stdin translate Latin-1 input into UTF-8 input |
| 570 | sys.stdin = EncodedFile(sys.stdin, 'utf-8', 'latin-1') |