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| # 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 | |