A buffered interface to random access streams. The constructor creates a reader and writer for a seekable stream, raw, given in the first argument. If the buffer_size is omitted it defaults to DEFAULT_BUFFER_SIZE.
| 1391 | |
| 1392 | |
| 1393 | class BufferedRandom(BufferedWriter, BufferedReader): |
| 1394 | |
| 1395 | """A buffered interface to random access streams. |
| 1396 | |
| 1397 | The constructor creates a reader and writer for a seekable stream, |
| 1398 | raw, given in the first argument. If the buffer_size is omitted it |
| 1399 | defaults to DEFAULT_BUFFER_SIZE. |
| 1400 | """ |
| 1401 | |
| 1402 | def __init__(self, raw, buffer_size=DEFAULT_BUFFER_SIZE): |
| 1403 | raw._checkSeekable() |
| 1404 | BufferedReader.__init__(self, raw, buffer_size) |
| 1405 | BufferedWriter.__init__(self, raw, buffer_size) |
| 1406 | |
| 1407 | def seek(self, pos, whence=0): |
| 1408 | if whence not in valid_seek_flags: |
| 1409 | raise ValueError("invalid whence value") |
| 1410 | self.flush() |
| 1411 | if self._read_buf: |
| 1412 | # Undo read ahead. |
| 1413 | with self._read_lock: |
| 1414 | self.raw.seek(self._read_pos - len(self._read_buf), 1) |
| 1415 | # First do the raw seek, then empty the read buffer, so that |
| 1416 | # if the raw seek fails, we don't lose buffered data forever. |
| 1417 | pos = self.raw.seek(pos, whence) |
| 1418 | with self._read_lock: |
| 1419 | self._reset_read_buf() |
| 1420 | if pos < 0: |
| 1421 | raise OSError("seek() returned invalid position") |
| 1422 | return pos |
| 1423 | |
| 1424 | def tell(self): |
| 1425 | if self._write_buf: |
| 1426 | return BufferedWriter.tell(self) |
| 1427 | else: |
| 1428 | return BufferedReader.tell(self) |
| 1429 | |
| 1430 | def truncate(self, pos=None): |
| 1431 | if pos is None: |
| 1432 | pos = self.tell() |
| 1433 | # Use seek to flush the read buffer. |
| 1434 | return BufferedWriter.truncate(self, pos) |
| 1435 | |
| 1436 | def read(self, size=None): |
| 1437 | if size is None: |
| 1438 | size = -1 |
| 1439 | self.flush() |
| 1440 | return BufferedReader.read(self, size) |
| 1441 | |
| 1442 | def readinto(self, b): |
| 1443 | self.flush() |
| 1444 | return BufferedReader.readinto(self, b) |
| 1445 | |
| 1446 | def peek(self, size=0): |
| 1447 | self.flush() |
| 1448 | return BufferedReader.peek(self, size) |
| 1449 | |
| 1450 | def read1(self, size=-1): |