emkornfield commented on a change in pull request #7240: URL: https://github.com/apache/arrow/pull/7240#discussion_r429020431
########## File path: cpp/src/arrow/compute/exec_internal.h ########## @@ -0,0 +1,137 @@ +// 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. + +#pragma once + +#include <cstdint> +#include <memory> +#include <string> +#include <vector> + +#include "arrow/array.h" +#include "arrow/buffer.h" +#include "arrow/compute/exec.h" +#include "arrow/compute/kernel.h" +#include "arrow/status.h" +#include "arrow/util/visibility.h" + +namespace arrow { +namespace compute { + +class Function; + +namespace detail { + +/// \brief Break std::vector<Datum> into a sequence of ExecBatch for kernel +/// execution +class ARROW_EXPORT ExecBatchIterator { + public: + /// \brief Construct iterator and do basic argument validation + /// + /// \param[in] args the Datum argument, must be all array-like or scalar + /// \param[in] max_chunksize the maximum length of each ExecBatch. Depending + /// on the chunk layout of ChunkedArray. Default of -1 means no maximum, so + /// as greedy as possible + static Result<std::unique_ptr<ExecBatchIterator>> Make(std::vector<Datum> args, + int64_t max_chunksize = -1); + + /// \brief Compute the next batch. Always returns at least one batch. Return + /// false if the iterator is exhausted + bool Next(ExecBatch* batch); + + int64_t length() const { return length_; } + + int64_t position() const { return position_; } + + int64_t max_chunksize() const { return max_chunksize_; } + + private: + ExecBatchIterator(std::vector<Datum> args, int64_t length, int64_t max_chunksize); + + std::vector<Datum> args_; + std::vector<int> chunk_indexes_; + std::vector<int64_t> chunk_positions_; + int64_t position_; + int64_t length_; + int64_t max_chunksize_; +}; + +// "Push" / listener API like IPC reader so that consumers can receive +// processed chunks as soon as they're available. + +class ARROW_EXPORT ExecListener { + public: + virtual ~ExecListener() = default; + + virtual Status OnResult(Datum) { return Status::NotImplemented("OnResult"); } +}; + +class DatumAccumulator : public ExecListener { + public: + DatumAccumulator() {} + + Status OnResult(Datum value) override { + values_.emplace_back(value); + return Status::OK(); + } + + std::vector<Datum> values() const { return values_; } + + private: + std::vector<Datum> values_; +}; + +Status CheckAllValues(const std::vector<Datum>& values); Review comment: documentations. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org
