| # Copyright DataStax, Inc. |
| # |
| # Licensed under the Apache License, Version 2.0 (the "License"); |
| # you may not use this file except in compliance with the License. |
| # You may obtain a copy of the License at |
| # |
| # http://www.apache.org/licenses/LICENSE-2.0 |
| # |
| # Unless required by applicable law or agreed to in writing, software |
| # distributed under the License is distributed on an "AS IS" BASIS, |
| # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| # See the License for the specific language governing permissions and |
| # limitations under the License. |
| |
| cdef class BytesIOReader: |
| """ |
| This class provides efficient support for reading bytes from a 'bytes' buffer, |
| by returning char * values directly without allocating intermediate objects. |
| """ |
| |
| def __init__(self, bytes buf): |
| self.buf = buf |
| self.size = len(buf) |
| self.buf_ptr = self.buf |
| |
| cdef char *read(self, Py_ssize_t n = -1) except NULL: |
| """Read at most size bytes from the file |
| (less if the read hits EOF before obtaining size bytes). |
| |
| If the size argument is negative or omitted, read all data until EOF |
| is reached. The bytes are returned as a string object. An empty |
| string is returned when EOF is encountered immediately. |
| """ |
| cdef Py_ssize_t newpos = self.pos + n |
| if n < 0: |
| newpos = self.size |
| elif newpos > self.size: |
| # Raise an error here, as we do not want the caller to consume past the |
| # end of the buffer |
| raise EOFError("Cannot read past the end of the file") |
| |
| cdef char *res = self.buf_ptr + self.pos |
| self.pos = newpos |
| return res |
