| # Licensed to the Apache Software Foundation (ASF) under one |
| # or more contributor license agreements. See the NOTICE file |
| # distributed with this work for additional information |
| # regarding copyright ownership. The ASF licenses this file |
| # to you 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 StringBuilder: |
| """ |
| Builder class for UTF8 strings. |
| |
| This class exposes facilities for incrementally adding string values and |
| building the null bitmap for a pyarrow.Array (type='string'). |
| """ |
| cdef: |
| unique_ptr[CStringBuilder] builder |
| |
| def __cinit__(self, MemoryPool memory_pool=None): |
| cdef CMemoryPool* pool = maybe_unbox_memory_pool(memory_pool) |
| self.builder.reset(new CStringBuilder(pool)) |
| |
| def append(self, value): |
| """ |
| Append a single value to the builder. |
| |
| The value can either be a string/bytes object or a null value |
| (np.nan or None). |
| |
| Parameters |
| ---------- |
| value : string/bytes or np.nan/None |
| The value to append to the string array builder. |
| """ |
| if value is None or value is np.nan: |
| self.builder.get().AppendNull() |
| elif isinstance(value, (bytes, str)): |
| self.builder.get().Append(tobytes(value)) |
| else: |
| raise TypeError('StringBuilder only accepts string objects') |
| |
| def append_values(self, values): |
| """ |
| Append all the values from an iterable. |
| |
| Parameters |
| ---------- |
| values : iterable of string/bytes or np.nan/None values |
| The values to append to the string array builder. |
| """ |
| for value in values: |
| self.append(value) |
| |
| def finish(self): |
| """ |
| Return result of builder as an Array object; also resets the builder. |
| |
| Returns |
| ------- |
| array : pyarrow.Array |
| """ |
| cdef shared_ptr[CArray] out |
| with nogil: |
| self.builder.get().Finish(&out) |
| return pyarrow_wrap_array(out) |
| |
| @property |
| def null_count(self): |
| return self.builder.get().null_count() |
| |
| def __len__(self): |
| return self.builder.get().length() |